Differences of Sex Development: General Approach

Differences or disorders of sex development (DSD): Chicago classification and updates, assessment of newborns and adolescents, diagnostic algorithm, multidisciplinary team, and European and international consensuses.

Literature and regulatory information updated: 6 October 2026.

0. Initial Reference Table

1. Introduction

The expression “differences of sex development” denotes a heterogeneous set of congenital conditions, rather than a single disease. Their common denominator is discordance, or atypicality, between the levels at which sex is established during development: chromosomal sex, determined at fertilisation; gonadal sex, which depends on differentiation of the bipotential gonad into a testis or ovary; and internal and external anatomical sex, resulting from gonadal hormone action [3]. This organisation into levels explains why the clinical approach starts with three successive questions — what is the chromosome complement, what gonadal tissue exists and what hormones were produced and recognised — and why the same presentation, atypical genitalia in a newborn, may represent entities with different prognoses, life-threatening risks and genetic counselling.

Until the beginning of the twenty-first century, medical literature used terms such as true hermaphroditism, male and female pseudohermaphroditism, sex reversal and intersex. In October 2005, the US Lawson Wilkins Pediatric Endocrine Society (LWPES) and the European Society for Paediatric Endocrinology (ESPE) convened approximately 50 international experts in Chicago, organised into working groups that answered predefined questions in writing based on literature review; the final document was published in 2006 in two journals [1, 8, 14]. The consensus considered these terms to be perceived as pejorative by many patients and confusing to professionals and families, and proposed the designation disorders of sex development (DSD), defined as congenital conditions in which development of chromosomal, gonadal or anatomical sex is atypical [1]. The new nomenclature replaced “male pseudohermaphroditism”, “undervirilisation” or “undermasculinisation” of an XY individual and “mixed” or “partial gonadal dysgenesis” with “46,XY DSD”; “46,XY sex reversal” and “XY female” with “46,XY complete gonadal dysgenesis”; and “true hermaphroditism” with “ovotesticular DSD” [2, 8]. In table 1 of the original text, the terms “female pseudohermaphroditism”, “overvirilisation” and “masculinisation” of an XX person became “46,XX DSD”, and “XX male” or “XX sex reversal” became “46,XX testicular DSD”; “mixed gonadal dysgenesis” does not appear among the replaced terms, and the example classification in the same article places 45,X/46,XY (mixed gonadal dysgenesis, ovotesticular DSD) under sex chromosome DSD, so inclusion of mixed gonadal dysgenesis in the 46,XY group is a GeneReviews interpretation applicable to cases with a 46,XY karyotype [1, 2]. The consensus also requested avoidance of unnecessary references to karyotype and preference for descriptive names, such as “androgen insensitivity syndrome”, whenever possible [1]. The same article estimated genital abnormalities in 1 in 4500 births [1].

Adoption was rapid in Europe. A survey of 60 centres in 23 European countries, published in 2010, found that all respondents used the new terminology, 57% regularly included the recommended subspecialists, 95% offered psychological support and 65% used a diagnostic algorithm; 52% reported fewer clitoroplasties than in previous years [15]. In 2016, a global update, including representatives of support and advocacy groups, reaffirmed quality of life as the central objective, advocated full and ongoing disclosure of information to patients and parents, and recognised that it remains impossible to predict gender identity development with certainty in an individual case, just as risks persist in decisions about genital surgery or germ cell removal in childhood [10]. The document, endorsed by ESPE, the North American Pediatric Endocrine Society and the paediatric endocrine societies of Australia, the Asia-Pacific region, Japan, Latin America and China, noted that data remained insufficient on sex assignment, predictors of gender identity, the timing of and consent to surgery, and fertility preservation [10]. On nomenclature, it recorded the arguments in favour of the term DSD (biological accuracy, access to care and insurance, integrated care models, no overlap with transgender, gender dysphoria or homosexuality, a framework for research and funding) and the objections of advocacy organisations: the stigma of the word “disorder”, the sexual connotation of “sex”, the refusal of some participants, such as men with CAH, to enter studies under this designation, and the preference of some for “intersex” or “differences” [10]. The word disorders has meanwhile frequently been replaced by differences to reduce stigma; GeneReviews considers “disorders” still appropriate among professionals [2, 8]. In the European dsd-LIFE study, 69% of 1040 participants considered the term disorders of sex development applicable to their condition or were neutral, and most preferred the specific name of their diagnosis; the authors recommend assessing each person's preference during consultation [16].

At European level, the British Society for Endocrinology guidance, published in 2011 and revised in 2015, focused on the initial assessment of newborns and adolescents [9]. The second revision, begun in 2020 and published in 2021, kept that focus, recommends the term “atypical” rather than “ambiguous” to describe the genitalia and incorporates high-throughput sequencing into the diagnostic pathway [17]. COST Action BM1303 “DSDnet”, representing 23 European Union Member States, 3 neighbouring countries and 5 partner countries, approved a consensus on lifelong care in September 2017 and published a position paper on molecular diagnosis [4, 7]. The dsd-LIFE study recruited 1040 adolescents and adults at 14 centres in France, Germany, the Netherlands, Poland, Sweden and the United Kingdom between February 2014 and September 2015, becoming the largest cross-sectional sample of people with conditions classified as DSD [18]. The European Reference Network for rare endocrine conditions (Endo-ERN) includes a thematic group dedicated to differences of sex development and maturation, with patient representatives involved in governance [4, 13]. In the United States, the Differences of Sex Development Translational Research Network (DSD-TRN) is a translational research network funded by the National Institutes of Health [8]. In 2026, Japanese clinical practice guidelines were published in English, with 31 clinical questions assessed using GRADE (Grading of Recommendations, Assessment, Development and Evaluation) [5], and the first update of the German guideline released its recommendations on gonadal tumour risk [19].

This article covers the general approach: classification, initial assessment, diagnostic algorithm, organisation of care, management principles and counselling. CAH, Turner and Klinefelter syndromes and androgen insensitivity appear only insofar as they affect general diagnostic reasoning.

2. Molecular Genetics and Pathophysiology

2.1. Sex determination and differentiation

Genetic sex is determined at fertilisation. In sex chromosome aneuploidies, the presence of a Y chromosome promotes male differentiation (for example, 47,XXY and 47,XYY), and a single X chromosome suffices for female development, as in 45,X, although full ovarian development requires two X chromosomes [3]. Before 7 weeks of gestation, the gonadal primordia are histologically identical in both sexes, and both have Wolffian ducts (precursors of the vas deferens, epididymis and seminal vesicles) and Müllerian ducts (precursors of the Fallopian tubes and uterus) [3]. Towards the end of the first trimester, the product of SRY (sex-determining region Y), located at Yp11.2, triggers differentiation of the undifferentiated gonad into a testis; if SRY is absent, deleted or altered, the gonad does not differentiate into a testis [3, 8]. The testis produces anti-Müllerian hormone (AMH, also called Müllerian-inhibiting substance), which causes Müllerian duct regression; testosterone stabilises Wolffian derivatives; and dihydrotestosterone (DHT), formed from testosterone by 5α-reductase type 2, is crucial for masculinisation of the external genitalia, which begins from 8 weeks [3, 9, 20]. Until 12 weeks, external genitalia look identical in both sexes and, until 20 weeks, ultrasound determination of fetal sex may be unreliable [3].

The SRY protein is a transcription factor with an HMG domain; SOX9 is the immediate downstream target in the male pathway [8]. Testicular and ovarian pathways mutually repress each other, explaining the two directions of gonadal DSD: loss of function of pro-testicular genes in 46,XY individuals produces gonadal dysgenesis, whereas gain of function or ectopic expression of pro-testicular genes, or loss of function of pro-ovarian genes, in 46,XX individuals produces testicular or ovotesticular DSD [8, 21]. Several genes act through dosage: duplications of FGF9, SOX3 or SOX9 have been described in 46,XX DSD, duplications of DAX1 (NR0B1) or WNT4 and deletions of ATRX, DMRT1, EMX2 or WT1 in 46,XY DSD [7].

2.2. Molecular mechanisms in 46,XY gonadal DSD

46,XY gonadal dysgenesis covers a spectrum from complete dysgenesis (female external genitalia, uterus and Fallopian tubes present and streak gonads or dysgenetic testes) to partial forms, with ambiguous genitalia, penoscrotal hypospadias with or without ventral curvature (chordee), micropenis or scrotal abnormalities, absent or complete Müllerian structures and gonads ranging from normal testis to ovotestis, dysgenetic testis or streak gonad [2]. GeneReviews estimates that approximately 60% of people with a non-syndromic disorder of testicular development have a genetic aetiology identified through molecular testing, based on the Brazilian cohort of Gomes and colleagues [2, 12].

NR5A1 variants illustrate the difficulty of counselling in these conditions. Steroidogenic factor 1 (SF-1) participates in adrenal and gonadal development; it was initially identified in 46,XY DSD with combined adrenal and gonadal defects, but most subsequently described variants are associated with isolated gonadal or reproductive phenotypes, and asplenia or hyposplenia has been reported in some carriers [4]. Transmission frequently occurs from 46,XX mothers, and fertile 46,XY fathers have been described [8].

2.3. 46,XX testicular and ovotesticular DSD

Approximately 80% of people with non-syndromic 46,XX testicular DSD have a small Y chromosome fragment including SRY, resulting from abnormal X-Y exchange between homologous loci during paternal meiosis, usually with translocation onto the short arm of the X [8]. Absence of Yq AZF (azoospermia factor) loci explains the consistent azoospermia [8]. In cases without SRY, known mechanisms are copy number variants (CNV) in or around SOX3 or SOX9, leading to ectopic expression or overexpression of these genes, and specific NR5A1 and WT1 variants [8]. SOX9 duplications affect enhancers located in a gene desert up to 2 megabases (Mb) upstream of the gene [8].

The NR5A1 variant corresponds to substitution of cytosine by thymine at nucleotide 274 of the coding sequence, replacing arginine with tryptophan at codon 92; the WT1 variant corresponds to substitution of guanine by adenine at nucleotide 1499, replacing arginine with glutamine at codon 500. Both were confirmed on the MANE Select transcript (NM_004959.5 and NM_024426.6; genomic coordinates NC_000009.12:g.124500686G>A and NC_000011.10:g.32389128C>T on GRCh38) using VariantValidator and are classified in ClinVar as pathogenic/likely pathogenic (NR5A1, record 265792, multiple submitters without conflict, evaluated July 2026) and pathogenic (WT1, record 664113, evaluated March 2025) [8, 23, 24]. 46,XX ovotesticular DSD is defined by the histological presence of testicular and ovarian tissue, as an ovotestis or an ovary and contralateral testis; all known genetic causes of 46,XX testicular DSD may also produce ovotesticular DSD, and phenotypic variability in SRY translocations may result from differential inactivation of the X carrying Y material [6, 8]. An autosomal recessive form associates RSPO1 with palmoplantar hyperkeratosis predisposing to cutaneous squamous cell carcinoma and 46,XX testicular or ovotesticular DSD [4, 8].

2.4. Disorders of androgen synthesis and action and androgen excess

When the testis forms but testosterone and DHT production or action fails, the 46,XY child has testicular gonads, Müllerian regression (AMH is produced by Sertoli cells) and variable undermasculinisation [9]. The British guideline organises these conditions by hormone profile: low testosterone and precursors (proximal steroidogenesis defects, luteinising hormone receptor defects and gonadal dysgenesis), low testosterone with elevated precursors (17α-hydroxylase, P450 oxidoreductase, 3β-hydroxysteroid dehydrogenase type 2 and 17β-hydroxysteroid dehydrogenase type 3 deficiencies), normal testosterone with low DHT (5α-reductase type 2 deficiency) and normal testosterone and DHT (androgen receptor disorders) [9].

In 46,XX DSD with androgen excess, the ovaries and uterus are normal and virilisation results from fetal androgens (CAH due to 21-hydroxylase, 11β-hydroxylase, 3β-HSD2 or POR deficiency), fetoplacental androgens (aromatase deficiency, CYP19A1, with maternal virilisation) or maternal androgens (luteoma, exogenous androgens) [4, 5, 9]. 21-hydroxylase deficiency accounts for 90–95% of CAH cases and approximately 90–95% of 46,XX DSD with atypical genitalia [7, 9, 21]. An alternative androgen pathway (backdoor), dependent on AKR1C2 and AKR1C4, also exists; its loss causes 46,XY DSD with DHT deficiency [2, 7].

2.5. Sex chromosome DSD and mosaicism

Sex chromosome mosaicism usually results from postzygotic mitotic nondisjunction, and the normal cell line attenuates the phenotype [26]. The 45,X/46,XY karyotype produces a spectrum from Turner syndrome and mixed gonadal dysgenesis to a phenotypically normal male; the proportion of 45,X cells in amniotic fluid, blood or fibroblasts does not predict the genital or gonadal phenotype [26]. DSD due to 46,XX/46,XY chimerism may result from admixture of cells from a vanishing twin or from fertilisation involving more than two genetically distinct gametes (tetragametic chimerism) [26]. Tissue mosaicism, including SRY present only in the gonad, explains discordant results between blood and gonadal tissue [8, 21].

2.6. Beyond coding variants

Even with massively parallel sequencing, causal variants are identified in only 35–45% of 46,XY DSD in research series, and clinical yield is lower [21]. Proposed explanations include variants in regulatory regions (for example, duplication of an enhancer upstream of AR, a 3-base-pair deletion in the SRY promoter in 46,XY complete dysgenesis), oligogenic inheritance, mosaicism, complex structural variants and epigenetic alterations [21]. Approximately 89% of pathogenic variants recorded in ClinVar lie in coding sequence (99% including adjacent regions), but the exome represents only 1–2% of the genome [21]. COST Action DSDnet acknowledges that some missing genetic variation may represent non-coding variants in regulatory elements of transcription factors such as SRY, SOX9, NR5A1 and FOXL2, detectable by genome sequencing [7].

3. Clinical Spectrum and Manifestations by System

3.1. Presentations by age

In newborns, the most frequent presentation is atypical genitalia. In practice, infants are divided into apparently male with atypical genitalia, apparently female with atypical genitalia and those with truly ambiguous genitalia; the same 46,XX girl with CAH may present as a girl with clitoromegaly or as a boy with bilateral undescended testes [9]. The genital spectrum includes micropenis or clitoromegaly, labioscrotal fusion or bifid scrotum, palpable or impalpable gonads, abnormal urethral meatus position and ventral curvature of the phallus [3]. Palpable gonads in the labioscrotal folds or inguinal region are probably testes or, less frequently, ovotestes [3]. Other neonatal presentations are discordance between prenatal chromosomal sex and phenotype at birth, an inguinal hernia containing a gonad in a child with female genitalia and, in boys with classical CAH, a salt-wasting crisis between 7 and 10 days of life, with failure to thrive, dehydration, hyponatraemia, hyperkalaemia, acidosis and sometimes hypoglycaemia [5, 9, 27].

Hypospadias is the most frequent isolated presentation within the spectrum. The urethral meatus lies proximally on the ventral penile surface, the prepuce is incomplete ventrally and ventral curvature may be present, increasing with more proximal meatal position; the frequency cited in the Oxford Desk Reference is 6.4 per 1000 male live births [20]. In a study from northeastern France, 80% of cases were mild and more than 90% of these had no other malformations; in severe forms, associated malformations are more frequent and the aetiology was established in approximately one third [20]. Epispadias, with the meatus on the dorsal surface, occurs in approximately 1 in 117,000 births, with a male predominance of 5:1 [20].

Oxford Desk Reference classification; ventral curvature may prevent severity assessment until correction during the first operation [20].

In adolescence, the British guideline describes three typical presentations: a girl with primary amenorrhoea, with or without breast development; a girl who virilises at puberty; and a boy with delayed puberty [9]. Clitoromegaly and hirsutism at puberty combined with primary amenorrhoea is the classical presentation of 17β-HSD3 and 5α-reductase type 2 deficiencies, without Müllerian structures; in partial gonadal dysgenesis, NR5A1 alterations and ovotesticular DSD, mild clitoromegaly present at birth may have been overlooked and become apparent in adolescence [9]. In a series cited by the Oxford Desk Reference, the four most frequent causes of primary amenorrhoea were gonadal dysgenesis (48.5%), congenital absence of the uterus and vagina (16.2%), gonadotrophin-releasing hormone deficiency (8.3%) and constitutional delay (6.0%) [28].

In adulthood, DSD may be recognised during infertility assessment. Approximately 85% of people with non-syndromic 46,XX testicular DSD present after puberty with typical pubic hair and penile size, small testes, gynaecomastia and azoospermia, and approximately 15% present with ambiguous genitalia at birth; SRY-positive forms have less hypospadias and less gynaecomastia than SRY-negative forms, which tend to present with ambiguous genitalia, almost always gynaecomastia at puberty and shorter stature [8].

3.2. 45,X/46,XY mosaicism

Mixed gonadal dysgenesis associated with 45,X/46,XY may manifest with asymmetrical gonads, Turner syndrome features and short stature. Children with 45,X/46,XY have a high risk of short adult stature, similar to girls with Turner syndrome, regardless of growth hormone treatment, and cardiovascular pathology resembles that of Turner syndrome irrespective of genital phenotype [4]. Among 45,X/46,XY males, approximately 80% have spontaneous puberty, but more than half of those diagnosed in childhood because of atypical genitalia required testosterone at puberty, compared with 15% of those diagnosed in adulthood [5]. In the series of 27 prenatally diagnosed cases by Telvi and colleagues, four had mild intellectual disability and two signs of autism, and three boys apparently normal at birth later developed dysgenetic testes with infertility and Turner features [26].

3.3. Associated abnormalities and extragenital involvement

In the international I-DSD registry, 168 of 649 accessible cases (26%) had at least one associated condition; the proportion was 45% (19/42) in 45,X/46,XY, 24% (112/460) in 46,XY and 22% (27/121) in 46,XX [29]. In the 112 46,XY cases with abnormalities, the most frequent were small for gestational age (23%), cardiac abnormalities (20%) and central nervous system abnormalities (20%); in the 27 46,XX cases, skeletal (44%) and renal (30%) abnormalities [29]. In a German national registry, 37.5% of newborns with ambiguous genitalia had associated malformations [30].

3.4. Endocrine, skeletal and metabolic manifestations

Primary adrenal insufficiency accompanies some DSD (CAH, STAR, CYP11A1, HSD3B2, POR, NR5A1) and may cause a life-threatening adrenal crisis in the first days of life [5, 7]. Reduced bone mineral density is frequent in adults: it has been described in women with disorders of 46,XX ovarian development, in up to 70% of women with CAH aged 30 years or older (attributed mainly to corticosteroid therapy) and in women with complete androgen insensitivity who underwent gonadectomy [4]. Sex chromosome DSD are associated with increased risk of autoimmune disease, metabolic disorders and type 2 diabetes; hypertension is intrinsic to 11β-hydroxylase and 17α-hydroxylase deficiencies and may result from excess fludrocortisone [4].

3.5. Mental health, gender identity and quality of life

In dsd-LIFE, among 1022 adults (mean age 32.1 years), clinical cut-off scores were reached by 19.5% for anxiety, 7.1% for depression, 4.1% for attention deficit hyperactivity disorder and 9.1% for autism; men with Klinefelter syndrome and XY DSD had mean anxiety and depression scores above population norms, and self-esteem, satisfaction with care, body dissatisfaction and experiences of shame were associated with symptoms [32]. Most people with DSD identify with the gender assigned at birth, but rates of gender dysphoria, intersex or intergender identities and gender change exceed those in the general population [4]. The Japanese guideline, based on a meta-analysis, reports gender incongruence in 15% (95% confidence interval, 13–17%) of people with DSD, with approximately 2% in complete androgen insensitivity and approximately 4% in 46,XX women with 21-hydroxylase deficiency; 13% of people with 5α-reductase deficiency and 15% of people with 17β-HSD deficiency initially raised female changed to male [5].

The 2016 global update considers it methodologically weak to link a diagnosis to a single psychometric measure, because well-being depends on physical health, age, social values and access to work, education, relationships and care, and varies at specific moments (initial diagnosis, development, symptom control, fertility treatment, the start and end of relationships) [10]. Studies with adults using more diverse methods described dissatisfaction with binary gender and with DSD terminology, fear of being devalued, negative body image, social isolation, a sense of not being entitled to relationships, concern centred on heterosexual intercourse, functional sexual difficulties, barriers to communication with close others and the experience of normalising surgery as a dilemma [10]. The high prevalence of normalising surgery makes it impossible to separate the impact of bodily differences from that of surgical management, and adult dissatisfaction with early surgery is high in some cohorts and lower in others; research on minority stress and on the protective effect of advocacy groups had not yet been applied to DSD [10]. Group psychological interventions improved the well-being of women with MRKH syndrome, group cognitive behavioural therapy reduced specific stressors, and cognitively and narratively based group work appeared to improve the self-evaluation of women with Turner syndrome [10].

4. Clinical Recognition and Warning Signs

4.1. Who should be investigated

Investigation is necessary when genital ambiguity prevents sex assignment at birth or when appearance is discordant with prenatal genetic tests [9]. The British guideline proposes the external masculinization score (EMS), separately scoring phallic size, labioscrotal fusion, location of each gonad and urethral meatus position, to a maximum of 12 [9]. In systematic examination of 423 apparently healthy term boys, 412 (98%) had an EMS of 12, 10 scored 11 and only 1 scored below 11 [9]. The calculation is illustrated in figure 1 of the guideline (Figure 1 — EMS, Society for Endocrinology). The European consensus indicates that a modified, non-binary version, applicable to boys and girls and intended to be more objective than the Prader scale, was undergoing multicentre validation [4]. In the 2021 revision, the British guideline recommends speaking of “atypical” rather than “ambiguous” genitalia, because in most cases the genitalia are atypical rather than ambiguous, and acknowledges that interpretation of genital appearance depends on the observer's experience; it adds to the EMS the external genitalia score (EGS), a sex-neutral alternative that describes urethral meatus position and genital tubercle length in more detail and correlates highly with the EMS [17]. The investigation criteria of that revision include isolated perineal hypospadias, isolated micropenis, isolated clitoromegaly, any familial hypospadias, isolated bilateral cryptorchidism, an EMS below 11 or an EGS below 10.5; in female newborns, clitoral length does not appear to depend on gestational age and a value above 8 mm warrants assessment; micropenis is defined as stretched penile length below −2.5 standard deviations of the mean, and studies from several countries support a threshold of 2 cm in the newborn [17]. The same revision considers birth weight useful, given the association between low birth weight, intrauterine growth restriction and XY DSD, and notes that complete investigation reveals an endocrine or genetic abnormality in at least a quarter of boys with XY DSD [17].

The Chicago consensus listed the following criteria suggestive of DSD in newborns: overt genital ambiguity (for example, cloacal exstrophy); apparently female genitalia with an enlarged clitoris, posterior labial fusion or an inguinal or labial mass; apparently male genitalia with bilateral cryptorchidism, micropenis, isolated perineal hypospadias or mild hypospadias with an undescended testis; family history of DSD, such as complete androgen insensitivity; and discordance between genital appearance and prenatal karyotype [1]. As later presentations, it listed unrecognised genital ambiguity, inguinal hernia in a girl, delayed or incomplete puberty, virilisation in a girl, primary amenorrhoea, breast development in a boy and macroscopic, sometimes cyclical, haematuria in a boy [1].

In boys with atypical genitalia, the probability of a chromosome abnormality is approximately 3% in isolated cryptorchidism, 7% in hypospadias and 13% in their combination [9]. In proximal hypospadias (penoscrotal, scrotal or perineal), biochemical and molecular studies identified a likely cause in approximately 30% of cases and, according to reports of genetic analysis in XY DSD cited in 2015, in approximately 40% [9]. In Albers' series, cited by the Oxford Desk Reference, a cause was identified in 12 of 33 patients with severe hypospadias; in Boehmer's series, approximately one third of 63 severe cases had an identified aetiology [20].

4.2. History and examination

The history should include a three-generation pedigree assessing consanguinity, maternal health and medication exposures during pregnancy (including maternal virilisation, suggesting aromatase or POR deficiency, and antiseizure medicines in hypospadias), and a detailed pregnancy and birth weight history, given the association between low birth weight and hypospadias [3, 5, 20]. Examination records phallic length, labioscrotal fold status, gonadal presence, location and dimensions, meatal position and ventral curvature, and looks for extragenital abnormalities; in hypospadias, additional assessment includes blood pressure and renal masses (Wilms tumour), growth parameters, head circumference, hypertelorism and swallowing or laryngeal problems (Opitz G/BBB syndrome), cleft palate and syndactyly between the second and third toes or postaxial polydactyly (Smith–Lemli–Opitz syndrome) [3, 20]. In obese adolescents, a buried penis should not be confused with micropenis [9]. Clinical photographs may be useful, but the European consensus requests minimising genital examinations, with explicit consent, avoiding repeated examinations, photography without consent and the presence of multiple professionals [3, 4].

The 2016 global update adds to the history maternal exposure to teratogens, endocrine disruptors or drugs, unexplained deaths in the family and the fertility of grandparents, aunts and uncles, which is useful especially in complete androgen insensitivity [10]. On examination, which should be meticulous and unhurried, with anthropometry and vital signs, skeletal features of Antley–Bixler syndrome suggest POR deficiency, campomelic dysplasia suggests SOX9, and midline facial or neurological defects or optic nerve hypoplasia suggest pituitary deficiencies; bilaterally impalpable gonads raise suspicion of a virilised girl with CAH, genital asymmetry with a single palpable gonad suggests gonadal dysgenesis with 45,X/46,XY, and transverse testicular ectopia indicates persistent Müllerian duct syndrome [10]. Anogenital distance has no clinical utility, owing to the lack of normative values and of measurement precision, and the EMS is the proposed alternative [10]. Developmental field defects (cloacal anomalies, anorectal malformations, bladder exstrophy–epispadias complex, VATER/VACTERL associations), penoscrotal transposition with hypospadias and aphallia are not classified by the Prader scale and are, as a rule, accompanied by normal gonadal development and function [10]. In adolescents, assessment requires attention to privacy, emotions and cognitive capacity, because the diagnosis may shake identity and self-esteem; examination includes blood pressure and dysmorphic features (Turner features in 45,X/46,XY), and Wilms tumour may be the presentation of Denys–Drash syndrome, small firm testes with learning difficulties and tall stature suggest Klinefelter syndrome, and primary amenorrhoea with normal breast development, sometimes with renal and vertebral anomalies, suggests MRKH syndrome [10].

4.3. Initial communication with the family

The first encounter is crucial because first impressions persist; GeneReviews reproduces this recommendation from the 2006 consensus [2]. The Japanese guideline recommends (strong recommendation, expert opinion) explaining the possibility of DSD and the need for assessment before sex assignment, avoiding hasty communication of a provisional sex and avoiding stigmatising terminology or behaviour [5]. The British guideline recommends that discussions be led by one professional, other team members avoid conveying isolated results, and clinical psychology support be offered to all parents of newborns with suspected DSD when sex assignment is delayed [9]. Expressions such as “differences” or “variations” of sex development may help introduce the concept [9].

5. Diagnosis: Criteria, Tests and Algorithms

5.1. Chicago classification and updates

There are no single diagnostic criteria for the group; diagnosis consists of identifying the specific entity. Karyotype defines the first classification level and is mandatory as an initial step [7]. Figure 1 of the 2018 European consensus (Figure 1 — DSD classification, Cools et al.) and table 4 of the Japanese guideline organise the entities as summarised below [4, 5].

5.2. Newborn algorithm

Assessment of newborns with atypical genitalia should proceed in close collaboration with paediatric endocrinology [3]. In all children with ambiguous genitalia or bilaterally impalpable gonads, first-tier investigations define the sex chromosomes, delineate the internal genitalia by pelvic ultrasound and exclude potentially fatal CAH through blood glucose, 17OHP and electrolytes [9]. 17OHP is generally unreliable before 36 hours and, in salt-wasting CAH, electrolytes rarely become abnormal before day 4; in the 2015 version, PCR or FISH results with X and Y markers were to be available within one working day and 17OHP within two working days at specialist centres [9]. The 2021 revision sets a maximum of two working days for both results (PCR or FISH and 17OHP) and points out that 17OHP may be falsely elevated in preterm or sick newborns, as well as in rare forms of CAH [17]. When CAH is strongly suspected and the child requires immediate corticosteroid treatment, serum samples for 17OHP, testosterone, androstenedione and, if possible, renin (in this priority order) and at least one urine sample (minimum 5 mL) for a urinary steroid profile should first be collected and stored [9]. In 2021, the priority list came to include renin activity and aldosterone after androstenedione, the urine may be a spot or 24-hour sample (at least 5 mL), basal or stimulated cortisol is considered difficult to interpret in the newborn, especially if preterm or exposed to glucocorticoids before or after delivery, and each region should have a written first-tier protocol, accessible to all professionals, covering sampling, sample transport and contacts [17]. The 2006 consensus proposed as first-line investigations in newborns karyotyping with X and Y probe detection (even with a prenatal karyotype), abdominopelvic ultrasound and measurements of 17OHP, testosterone, gonadotrophins, AMH, electrolytes and urinalysis, with results usually available within 48 hours and sufficient for a working diagnosis; hCG and ACTH stimulation tests, urinary steroid profiling by gas chromatography–mass spectrometry, imaging and gonadal biopsies were second-line [1]. At the time, only approximately 20% of DSD had a specific molecular diagnosis and only 50% of 46,XY children with DSD received a definitive diagnosis, whereas most virilised 46,XX newborns had CAH [1]. The Oxford Desk Reference also includes serum testosterone and genomic microarray in the absence of a definitive endocrine diagnosis, and recommends starting with interphase FISH or quantitative fluorescent PCR (QF-PCR) and proceeding to a full karyotype with mosaicism testing [3].

In a child with impalpable gonads, a 46,XX karyotype, very high 17OHP and a uterus, CAH due to 21-hydroxylase deficiency is very likely; the urinary steroid profile confirms the diagnosis and identifies rare forms that also elevate neonatal 17OHP, such as 11β-hydroxylase and 3β-HSD2 deficiencies [9]. In children with a karyotype other than 46,XX, second-tier investigation aims to demonstrate the presence of testis and the adequacy of androgen production and action: serum AMH, human chorionic gonadotrophin (hCG) stimulation testing, proteinuria testing, detailed imaging and, if necessary, laparoscopy [9]. In the 2021 revision, this tier includes from the outset gonadotrophins, testosterone, AMH and/or inhibin B, imaging and laparoscopy; proteinuria testing may need to be repeated when suspicion of a WT1 variant is high, because glomerulopathy has a variable onset; and, with panels and exome or genome sequencing, more extensive biochemical and radiological investigations may await the genetic result, which may avoid costly and invasive tests [17]. With a 45,X/46,XY karyotype, normal testosterone in the first 8 weeks, a period of high neonatal gonadal activity, indicates male gonadal development; FSH and LH help assess whether the gonad is functional [3]. The 2016 global update proposes as first-line investigations in the newborn 17OHP, electrolytes, androgens, AMH and gonadotrophins, together with definition of the sex chromosomes, and points out that, with genotyping, a salt-wasting crisis is no longer needed to diagnose that form of CAH [10]. For interpretation, it cross-references androgens and AMH with the karyotype, as summarised below; gonadotrophins are usually very high in dysgenetic DSD, normal or mildly raised in steroid synthesis defects and partial insensitivity, and may be low in complete insensitivity [10]. Because AMH and androgens are physiologically low in the male newborn and rise from the 3rd week, repeated measurements may be needed; their basal values reflect the mass of functioning Sertoli and Leydig cells, ranging from very low in severely dysgenetic gonads or ovotestes with ovarian predominance to normal male values in mild dysgenesis or ovotestes with abundant testicular tissue [10].

Patterns described in the 2016 global update; values should be read in the light of assay characteristics and reference ranges for gestational and chronological age [10].

The Japanese guideline summarises the reasoning in an algorithm integrating karyotype, 17OHP, testosterone, AMH, Müllerian structures and maternal virilisation before genetic testing (Figure 2 — diagnostic algorithm, Japanese guideline) [5].

5.3. Endocrine tests and their interpretation

Hormone concentrations change during the first 100 days of life: in boys, testosterone and DHT may be elevated at birth, decrease below 1 nmol/L or become undetectable, rise from day 30 and peak around day 70 (minipuberty), before returning to prepubertal levels [9]. The 2016 global update describes the same dynamics in less detail (low testosterone on days 7–14 and a progressive rise up to 2–3 months) and recommends steroid measurement after extraction or chromatography, preferably by gas or liquid chromatography coupled with mass spectrometry (GC-MS or LC-MS/MS), which allow several analytes in a single sample [10]. In DSD, plasma steroids should be measured using liquid chromatography–tandem mass spectrometry (LC-MS/MS) or immunoassay after organic solvent extraction, because direct immunoassays have specificity problems [9]. Urinary steroid profiling by gas chromatography–mass spectrometry is the method of choice for combined defects such as POR deficiency, can be stored frozen for years and is inappropriate for 5α-reductase type 2 deficiency before 3 months of age [9]. The European consensus recommends chromatographic and mass spectrometry methods but recognises that these are not yet widely available and that interlaboratory standardisation has only begun [4]. The 2021 British revision recommends LC-MS/MS for plasma steroids in DSD, anticipates that combined measurement of 17OHP, 21-deoxycortisol and 11-deoxycortisol will give greater early diagnostic accuracy in CAH, advises an early neonatal urine collection and a later one, because fluctuations in the first months may create a diagnostic blind window, and a 24-hour collection when suspicion is high, since urinary metabolites vary over the day [17]. As for peptide hormones, current AMH assays have low inter-assay variability but require reference ranges by age, sex and method; in a male newborn with AMH near the lower limit, measurement should be repeated later in infancy, because AMH continues to rise in normal testes; inhibin B is more useful from late childhood, when AMH falls, and in the United Kingdom is not included in external quality assessment schemes; INSL3 (insulin-like peptide 3), a marker of Leydig cell activity, does not yet have an established role in DSD [17].

Adapted from table 2 of the British guideline; reference ranges depend on age, sex and method [9].

Persistently low AMH has a high predictive value for a low testosterone response to hCG, but normal AMH has a low predictive value for a normal response; undetectable AMH in bilateral anorchia may avoid surgical exploration [9]. The hCG test is invasive and second-line. Most British protocols use intramuscular hCG, 1000–1500 units on three consecutive days, which may be followed by 1500 units on two days per week for a further two weeks; in very young infants with an active axis, the test may be unnecessary if serial samples show elevated testosterone [9]. The response is considered normal if testosterone exceeds the upper prepubertal limit or doubles from baseline; DHT and androstenedione are assessed in the day 4 sample, and a low response should prompt a synthetic ACTH (Synacthen®) stimulation test to assess adrenal function [9]. The 2021 revision indicates the prolonged 3-week test when there is strong suspicion of absence of a functioning gonad (for example, bilateral cryptorchidism) or of hypogonadotrophic hypogonadism, recommends storing the day 22 sample for DHT or androstenedione if the day 4 sample is insufficient, considers that the urinary profile or AMH after hCG add no diagnostic value, and does not recommend the ACTH test in all XY DSD, but rather in diagnoses with a described association with primary adrenal insufficiency, on clinical suspicion or with low precursors in the urinary profile [17]. The 2016 global update accepts the prolonged hCG test for studying defects of steroidogenic proteins, but only after careful consideration, because of possible negative effects on the testes, and reserves the ACTH test for suspected steroidogenic defects common to the gonads and adrenals; the criteria for extended biochemical study that it lists (isolated perineal hypospadias, isolated micropenis, isolated clitoromegaly, familial hypospadias, EMS below 11) coincide with those of the British guideline [10]. In 5α-reductase type 2 deficiency, the testosterone/DHT ratio after hCG frequently exceeds 30:1, although cases with lower ratios occur [9]. The fall in sex hormone-binding globulin after androgens, absent in complete insensitivity and variable in partial insensitivity, is difficult to interpret in infants [9]. The Japanese guideline also mentions stimulation with human menopausal gonadotrophin (hMG) in suspected ovotesticular DSD, with oestradiol and inhibin A cut-offs suggestive of ovarian tissue, emphasising that hMG use is off-label and that its usefulness outside this context is not established [5].

5.4. Imaging and anatomical assessment

Ultrasound is first-line (adrenals, kidneys, pelvis, inguinal regions and scrotum); in newborns, the uterus, ovaries and adrenals should be identifiable, but reliability depends on the child and operator, presence of a uterine structure does not guarantee future function, and intra-abdominal testes and streak gonads are difficult to identify [9]. Magnetic resonance imaging (MRI) is reserved for cases in which ultrasound does not clarify Müllerian structural relationships or urinary abnormalities exist [9]. Genitoscopy has replaced diagnostic genitography, and laparoscopy is indicated in 46,XY infants with impalpable testes; in adolescents, a prepubertal uterus may be difficult to identify without prior oestrogen exposure, justifying, if suspected, a therapeutic oestrogen trial and repeat imaging after 6 months [9]. The Japanese guideline considers the diagnostic usefulness of laparoscopy and gonadal biopsy limited, to be weighed according to the suspected condition (weak recommendation, expert opinion); in a Korean series of 23 patients with suspected ovotesticular DSD undergoing biopsy or gonadectomy, 57% had ovotesticular DSD, 22% mixed gonadal dysgenesis and 22% other conditions [5]. GeneReviews warns that gonadal biopsy may fail through sampling error and impair gonadal growth [2].

5.5. Adolescent algorithm

In girls with primary amenorrhoea, the British guideline, in its 2015 version, recommended investigation at 14 years if there was no pubertal development and at 16 years if puberty, particularly breast development, had progressed; initial screening includes electrolytes, LH, FSH, prolactin, TSH, free T4, SHBG, androstenedione, oestradiol, testosterone and pelvic ultrasound, and karyotyping is indicated with elevated gonadotrophins or an absent uterus with normal breast development [9]. In boys, delayed puberty should be assessed from 14 years, with bone age, LH, FSH, testosterone and prolactin, and karyotyping if gonadotrophins are elevated, to exclude Klinefelter syndrome or 45,X/46,XY [9]. The Japanese guideline uses different thresholds: absence of pubertal signs from 15 years in boys and 13 years in girls, and absence of menarche from 15 years, with a strong recommendation for hormonal, imaging and chromosome assessment [5]. The difference reflects each document's context rather than a conflict about investigations. In the 2021 revision, the British guideline moved to recommending investigation at 13 years without breast development and at 15 years if puberty has progressed normally, thresholds that coincide with the Japanese ones, and keeps 14 years for boys; it added AMH or inhibin B to the initial screening of girls, accepts karyotype or microarray, reserves vaginal examination for the gynaecologist when dilation is being considered (it has no diagnostic value on its own) and recommends deferring physical examination until a relationship of trust with the adolescent exists, under anaesthesia if necessary [17]. The thresholds of 14 and 16 years therefore correspond to the 2015 version [9]. The 2016 global update proposes a biochemical reading of the adolescent with primary amenorrhoea: in a 46,XY girl with breast development, elevated androgens and AMH and no uterus, complete androgen insensitivity is the most likely diagnosis; without breast development, severe defects of Leydig cell steroidogenesis should be considered, with extremely low values of all gonadal steroids indicating LH receptor variants and low testosterone with elevated androstenedione suggesting 17β-HSD3 deficiency [10]. Clitoromegaly and hirsutism at puberty with primary amenorrhoea point to 17β-HSD3 or 5α-reductase type 2 deficiency and, less typically, to partial insensitivity; in 46,XX ovotesticular DSD, virilisation suggests testicular tissue, with AMH and testosterone above the female range, and the differential diagnosis includes CAH and virilising ovarian or adrenal tumours, distinguished by 24-hour urinary steroid profiling [10].

5.6. Genetic testing: strategy

The COST Action DSDnet position summarises the strategy in four points: karyotype defines the subgroup; CNV analysis should be added to first-line investigation in 46,XX and 46,XY, particularly with extragenital malformations; all newborns with DSD require complete steroid analysis to avoid missing adrenal insufficiency (STAR, CYP11A1, virilising CAH); in other cases, clinical and biochemical phenotyping should proceed alongside genetic testing, with a candidate gene panel or whole-exome sequencing (WES), reserving whole-genome sequencing (WGS) for characterisation of novel genes or suspected oligogenic aetiology [7]. QF-PCR detects sex chromosome markers within 1–2 days; microarray (CGH or SNP) may replace karyotyping, with results in 5–10 days, but does not detect balanced structural rearrangements and may be less effective for sex chromosome mosaicism [7]. GeneReviews describes two equivalent initial strategies: conventional karyotyping with sufficient cells to detect mosaicism and SRY FISH, or CMA, defining the sex chromosome complement, SRY presence and deletion/duplication syndromes; if CMA detects SRY deletion, targeted karyotyping clarifies translocations or complex rearrangements [2]. In 46,XX testicular DSD, metaphase FISH with an SRY probe should come first because it localises the translocation [8].

Adapted from table 2 of Délot and Vilain, 2021 [21].

The 2016 global update described the then current sequence in three steps (additional phenotypic information with urgent metabolic and endocrine tests and imaging; rapid identification of the sex chromosome complement by karyotype or FISH with X and Y probes and microarray; CNV testing in regions of known DSD genes), with single-gene or panel sequencing as the last step; it anticipated that exome or genome sequencing as a first-line test would come to provide rapid diagnosis in most cases, but listed the obstacles of the time (turnaround time, cost, coverage by insurers or national health systems, interpretation of incidental findings and of variants not recognised as pathogenic) and stressed that genetics alone does not explain the biological and psychological dimensions of DSD [10]. GeneReviews distinguishes the multigene panel option, when hormonal, gonadal or imaging data are distinctive, from the exome or genome option, when the phenotype is indistinguishable from many other DSD [2]. The Japanese guideline suggests rapid genetic testing before sex assignment in specific situations (weak recommendation), in particular 46,XY DSD with completely or almost completely female genitalia without an identified uterus, to assess androgen insensitivity and 5α-reductase or 17β-HSD3 deficiencies, and considers it of limited value when assignment depends mainly on the phenotype, as in partial insensitivity or CAH [5]. The 2015 British guideline recommended restricting exome/genome sequencing to studies with ethical approval and extended informed consent [9]; the 2018 European position paper and the 2026 Japanese guideline already integrate panel or exome testing into routine diagnosis [5, 7], and in the Endo-ERN survey 21 of 26 centres performed these tests for diagnostic purposes [33]. In the 2021 revision, the British guideline itself integrated high-throughput sequencing into diagnosis: it proposes QF-PCR followed by karyotype or, more often, microarray, consent for DNA storage and for genomic testing from the initial assessment, single-gene analysis only when a defined monogenic condition is suspected (for example, a biochemically defined steroidogenic defect) and a targeted panel or exome/genome with filters for DSD genes, preferring the panel for its quality coverage of the genes of interest and lower risk of incidental findings; without a causal variant or with a variant of uncertain significance, it considers exome or genome sequencing, especially with associated malformations, endocrine abnormalities, family history or consanguinity [17]. The yield may be below 50% in 46,XY DSD without a clear steroidogenic defect; pre-test counselling should cover variants of uncertain significance, variable gene coverage in exome/genome sequencing and the possibility of unsolicited findings, and interpretation is the responsibility of a diagnostic group including, at a minimum, a clinical geneticist, a molecular geneticist, a clinical biochemist and a paediatric endocrinologist; in England, the test is listed in the NHS National Genomic Test Directory [17].

5.7. Test limitations and report content

A negative test does not exclude genetic DSD. Panels have low-coverage regions and difficulty detecting CNV [11]; exome sequencing does not detect regulatory variants, and CMA may not detect CNV around SOX3 and SOX9, depending on probe density, so the laboratory should confirm that it reports CNV in the SOX9 gene desert [8]. Tissue mosaicism may make blood poorly representative: SRY has been found only in the gonad in some 46,XX DSD cases [8]. Among CNV detected in children with DSD, three quarters were initially classified as of uncertain significance, but half of these had previous DSD associations, demonstrating the need for interpretation resources and data sharing [7]. Most accredited laboratories follow the American College of Medical Genetics and Genomics (ACMG) five-class system and report pathogenic, likely pathogenic and uncertain significance variants in phenotype-related genes, with variants in other genes treated as secondary findings [7]. Except for some disruptive variants, genotype does not reliably predict steroidogenic capacity, sex steroid sensitivity or gender identity, maintaining hormonal assessment as complementary [7]. In androgen insensitivity, AR variants are found in more than 90% of complete phenotypes but only 20% (British guideline) to 56% (Japanese guideline) of partial phenotypes, and the diagnosis of partial insensitivity should be used only when molecularly confirmed [5, 9]. The report should identify the gene, versioned transcript (for example, NM_004959.5 for NR5A1), HGVS c. and p. nomenclature, zygosity, ACMG/AMP classification and technical limitations; familial segregation of a variant of uncertain significance is a research investigation and does not itself reclassify it. In cases without a molecular diagnosis, DNA banking should be considered [2].

5.8. Prenatal diagnosis

A DSD may be suspected prenatally because of family history or discordance between genital ultrasound and fetal genetic sex [7]. Non-invasive diagnosis can identify Y-specific markers, including SRY, in cell-free fetal DNA in maternal plasma from the 6th week, although most laboratories recommend sampling from 7 weeks; alternatively, SRY, karyotype and carrier status can be studied in chorionic villi (weeks 9–11) or amniocytes (weeks 15–20) [7]. When non-invasive prenatal screening suggests a typical sex chromosome complement, ultrasound showing genitalia of the other sex has been described in 1 in 14,300 pregnancies; in one series, about one third of discordances corresponded to errors (tube swaps, incorrect ultrasound identification) and a DSD was diagnosed at birth in 36%, a vanishing twin being a frequent cause [21]. For complete discordance between phenotypic sex and karyotype, the Oxford Desk Reference lists maternal contamination of the sample (the most likely cause), sample swap, true discordance (rare), chimerism due to a twin or lost twin (rare) and previous bone marrow transplantation from a donor of the other sex [3]. When non-invasive prenatal screening results suggest sex chromosome aneuploidy, maternal aneuploidy or mosaicism should be considered [34]. Very low maternal unconjugated oestriol on serum screening is most frequently caused, in viable pregnancies, by steroid sulfatase deficiency (X-linked ichthyosis); rare causes with 46,XY DSD include Antley–Bixler syndrome due to POR deficiency, in which oestriol may be undetectable, 17-hydroxylase deficiency, lipoid adrenal hyperplasia and Smith–Lemli–Opitz syndrome, to be considered in a 46,XY fetus with female genitalia on ultrasound [35]. According to a retrospective review cited in the 2016 global update, prenatal genetic testing is not practical for rare DSD without family history, and prenatal karyotyping with FISH is the most useful test when ultrasound suggests ambiguous genitalia; once the genetic diagnosis and recurrence risk are known, prenatal diagnosis becomes available in subsequent pregnancies [10]. The 2021 British revision reports that sex chromosome abnormalities are identified in about 1% of pregnancies with prenatal karyotyping, that about 40% of these pregnancies may end in termination, and that early referral for genetic counselling appears to be associated with a lower likelihood of termination [17].

6. Differential Diagnosis

The differential diagnosis of DSD has three levels: distinguish the main classes by karyotype, gonadal function and Müllerian structures; recognise syndromic forms from extragenital findings; and exclude non-genetic causes and sample errors. Absence of Müllerian structures separates most conditions with a functioning testis from 46,XY complete gonadal dysgenesis [2].

6.1. Salt wasting in newborns

Salt-wasting dehydration is part of the metabolic differential diagnosis in infants. Saudubray groups the “adrenal dysfunctions”: severe hyponatraemia with ambiguous genitalia at the end of the first week (CAH), with non-ambiguous genitalia at the end of the first week (hypoaldosteronism), ambiguous genitalia from infancy to early childhood (congenital adrenal hypoplasia) and late forms of CAH, and hypo- and pseudohypoaldosteronism with non-ambiguous genitalia [37]. X-linked congenital adrenal hypoplasia presents similarly to CAH in a boy in the first month, but 17OHP is normal or low; about one third have a contiguous deletion involving DAX1 (NR0B1), glycerol kinase and DMD, so creatine kinase measurement is recommended [27]. Pseudohypoaldosteronism causes salt wasting without virilisation, with normal 17OHP and testosterone, and requires salt but not hydrocortisone; the autosomal recessive form involves subunits of the epithelial sodium channel (SCNN1A, SCNN1B, SCNN1G) and the autosomal dominant renal form the mineralocorticoid receptor (NR3C2) [27]. An Italian observational study registered in 2025 seeks to quantify endocrine causes of neonatal salt wasting not attributable to 21-hydroxylase deficiency and not detected by newborn screening [38].

6.2. Syndromic DSD

6.3. Non-genetic causes and artefacts

COST Action DSDnet includes endogenous or exogenous maternal factors and endocrine disruptors among DSD causes, and acknowledges a putative category of epigenetic alterations [7]. Placental insufficiency is associated with 46,XY DSD in the European classification, and low birth weight reduces the probability of finding an AR variant [4, 9]. When prenatal karyotype and phenotype are discordant, maternal contamination, sample switching, chimerism and previous bone marrow transplantation from an opposite-sex donor should be excluded before accepting DSD [3, 26].

7. Treatments and Risk Management Strategies

7.1. Multidisciplinary team and network organisation

Long-term assessment and management should take place at a centre with an experienced interdisciplinary team including clinical genetics, endocrinology, surgery and mental health [2]. The British guideline sets as a minimum standard specialists in endocrinology, surgery and/or urology, clinical psychology or psychiatry, radiology, nursing and neonatology, with access to a wider team of adult endocrinology, plastic surgery, gynaecology, clinical genetics, clinical biochemistry, adult psychology, social work and, if possible, a clinical ethics forum [9]. In the newborn, the paediatric endocrinologist usually takes clinical leadership; the clinical geneticist facilitates urgent karyotyping, assesses the child with dysmorphic features, oversees genetic testing, ensures sample storage and provides counselling [9]. Because it is unrealistic for every hospital to have a complete team, the guideline proposes managed clinical networks, with shared protocols and remote consultation, and the international I-DSD registry [9]. The 2021 revision adds to the team a keyworker, who may be the clinical nurse specialist, and a service coordinator responsible for data management, audit and benchmarking of outcomes; it describes the Scottish managed clinical network, continuous surveillance through the Scottish Audit of Atypical Genitalia (SAAG) and the European EuRRECa registry (European Registries for Rare Endocrine Conditions), the European Reference Network eUROGEN for urology and the auditable standards of the DSD working group of the British Society for Paediatric Endocrinology and Diabetes (BSPED), and notes that in England DSD is a specialised service commissioned by NHS England, without a formal national network [17]. The 2016 global update distinguishes three team models, developed mainly after 2005: multidisciplinary, with simultaneous but independent contributions from each discipline; interdisciplinary, with joint work from each perspective and a deliberate sharing of knowledge, which reduces turf conflicts; and transdisciplinary, in which the concepts of the disciplines are synthesised into new models and all professionals are jointly accountable for each clinical goal (figure 1 of the article, which includes psychology or social work, bioethics, endocrinology, genetics and genetic counselling, urology, nursing and gynaecology) [10]. In dsd-LIFE, the level of structural quality of centres varied within each diagnosis and each country and was associated with participants' satisfaction with care [44]. In the European Union, Endo-ERN organises reference centres and offers virtual multidisciplinary consultation through the CPMS (Clinical Patient Management System) [4, 13].

7.2. Assignment of sex of rearing

All children should be given a sex of rearing, but assignment in a newborn with ambiguous genitalia should not be decided before expert assessment; in 46,XY DSD it is based on the diagnosis, expert opinion and the parents' convictions, and the assigned sex may not coincide with gender identity, which the person defines over time [2]. The Japanese guideline suggests assigning sex shortly after birth, after the necessary investigations (weak recommendation, expert opinion), in a context where birth registration requires the sex to be stated, and suggests deferring assignment when gonadal position, phallic size, meatal location, degree of scrotal formation or labial fusion and the presence of a vaginal opening depart from typical development (weak recommendation) [5]. The European consensus adds that initial decisions on social gender role can be changed according to the developing child's expression and that the goal is satisfaction with one's own gender; it advises against emotional decisions and proposes deferring non-urgent decisions, such as surgery, until psychological counselling has taken place [4]. The Chicago consensus based its recommendations on the data then available: more than 90% of 46,XX people with CAH and all 46,XY people with complete insensitivity raised female identified as women, which supported raising markedly virilised 46,XX newborns with CAH as female; about 60% of people with 5α-reductase type 2 deficiency raised female who virilised at puberty (and all those diagnosed in infancy and raised male) lived as men; in partial insensitivity, androgen biosynthesis defects and incomplete gonadal dysgenesis, about 25% were dissatisfied with their sex of rearing, whether male or female; the data supported male rearing in micropenis; and, in cloacal exstrophy raised female, more than 65% lived as women [1]. The same text asked that fertility potential be weighed in ovotesticular DSD and, in mixed gonadal dysgenesis, prenatal androgen exposure, testicular function, phallic development and gonadal location; it also warned that the notion of 18 months as the upper limit for an imposed reassignment should be treated with caution, that atypical gender role behaviour is not in itself an indication for reassignment and that, in the face of persistent dysphoria, the wish to change should be supported after prolonged psychological assessment [1]. The 2016 global update took up these recommendations with slightly different values (95% female identity in 46,XX CAH raised female; about 60% male identity in 5α-reductase deficiency; more than 50% change to male in 17β-HSD3 deficiency; female assignment also in LH receptor defects) and ranked the factors to be weighed: likely adult gender identity (the most important, but only tentatively predictable), expected quality of sexual function, surgical options and risks, fertility potential, evidence of fetal androgen exposure of the central nervous system, risk of gonadal malignancy, and family, social and cultural factors [10]. It added evidence from after 2006: prenatal androgen exposure influences gender-related behaviours, especially in 46,XX people and when identity is assessed dimensionally; people without fetal exposure (complete insensitivity, 46,XY complete gonadal dysgenesis) raised female retain that gender, with rare exceptions; genital appearance at birth correlates moderately with later gender behaviour, but not in non-hormonal malformations such as cloacal exstrophy or penile agenesis; and postnatal androgens may also contribute [10]. There is no biomarker of gender identity, and brain imaging studies, heterogeneous and unreplicated, do not allow individuals to be categorised [10]. For specific situations, the document proposed: in 46,XX CAH with Prader 4 or 5 genitalia, considering male rearing when the social and cultural environment supports it, on the basis of follow-up data beyond middle age; raising 46,XY newborns with non-hormonal malformations (cloacal exstrophy, penile agenesis), presumably with normal prenatal androgen exposure, as male; in 5α-reductase deficiency, deciding on the basis of physical development, hormone secretion, genotype and response to treatment, especially to DHT, with reports of satisfactory sexual function in people raised female; in partial insensitivity, male assignment only with demonstrated phallic growth under testosterone (and a causal variant, if identified) and consideration of female assignment in the absence of an androgenic effect; in 17β-HSD3 deficiency, assessment of all aspects, because sexual function is satisfactory in both sexes of rearing, with frequent dissatisfaction with penile length in those raised male and clinical distress in those raised female; and, in 46,XY micropenis, male assignment for most, except in partial insensitivity [10]. In ovotesticular DSD, about half of children are assigned to each sex, regardless of karyotype, and dysphoria or gender change in both directions has been reported [10]. In women with CAH from the Swedish cohort cited, orgasmic capacity did not correlate with sensitivity and did not differ from that of controls; sexual function and satisfaction scores were lower in the null genotype group, which also had more male-dominated occupations and more non-heterosexual orientation, with no difference in overall psychological well-being [10]. The incongruence data by diagnosis (section 3.5) are the main argument for female assignment in complete androgen insensitivity and 46,XX CAH and for caution in 5α-reductase and 17β-HSD3 deficiencies [5].

7.3. Information, psychological support and support groups

Conversations with parents and young people should take place on several occasions, in a calm setting, at a pace set by the family and with a shared record of what was discussed; the British guideline recommends offering clinical psychology to all adolescents with newly diagnosed DSD or who require medical or surgical intervention [9]. The 2021 revision further recommends immediate clinical psychology support for the parents of all newborns with suspected DSD whose sex assignment has been deferred, standardised assessment of the need for psychology at transfer to adult services, a written or audio record of the first conversations shared with the parents and the general practitioner, respect for the terms preferred by the person and the family (some peer groups prefer “intersex” or “variations of sex characteristics”), attention to interpreters and, where the family values it, involvement of a religious leader; contact details of peer groups, such as the CAH Support Group and dsdfamilies, should routinely be included in written information [17]. The European consensus recommends regular contact with the team (for example, every 1–2 years) even without medical problems, information for the child from an early age and at the child's own pace, and progressive information about fertility before adolescence [4]. The Japanese guideline suggests staged disclosure with psychological and peer support (weak recommendations) and describes in parents stress associated with uncertainty, post-traumatic stress symptoms, anxiety and depression [5]. The sources consulted cite as resources dsdfamilies, the AIS Support Group (AISSG), CLIMB and the CAH support group (livingwithcah.com), Accord Alliance, the Adrenal Hyperplasia Network, Hypospadias UK and national associations represented in the European consensus, such as DSDNederland [2–4, 9, 20]. The Chicago consensus already integrated psychosocial care by mental health professionals experienced in DSD as part of management, recommended planning with the parents, from diagnosis, the staged disclosure of facts about karyotype, gonads and fertility, offering adolescents opportunities to talk confidentially without their parents, and recognised that repeated genital examination and medical photography may be experienced as deeply shaming, so that photography should be performed, whenever possible, under anaesthesia for another procedure and with consent; in an appendix, it described the role of support groups in ending isolation and stigma and in improving services [1]. The 2016 global update frames peer support within the World Health Organization's Mental Health Action Plan 2013–2020 and advocates it as a primary intervention, alongside psychosocial support: it recommends introducing it as early as possible, with messages conveying that these differences are more common than is thought and that many families raise healthy children, and that the experienced family should take the initiative of contact, with the parents' permission, while the parents immediately receive written resources such as dsdfamilies.org and the Accord Alliance Handbook for Parents [10]. It describes models of integration into the clinic: an affected person as a team resource (a pilot at the Children's Hospital in Denver), volunteers available during clinic and at clinical meetings, and condition-specific open days at University College London Hospitals (for example, XY women or MRKH syndrome) [10]. For information and decision-making, it considers open and complete communication in the face of uncertainty mandatory, defines shared decision-making as a process of education, sharing of risks and benefits, making uncertainties explicit and allowing time for the family to reframe the options, and mentions communication training (distance learning, conversation guides), educational materials (dsdfamilies.org, interactyouth.org, dsdgenetics.org, accordalliance.org), a customisable list of materials being prepared within DSD-TRN and an online decision aid for parents, then under development [10]. Support groups call for evidence-based interventions, the inclusion of controversies in informed consent and participation from the design of studies onwards (community-based participatory research), and table 1 of the article lists support and advocacy resources by continent, including groups in Argentina, Colombia, Chile, Mexico and several European countries [10]. A North American study registered in 2025 is evaluating a narrative writing intervention to reduce anxiety in parents of children with DSD or hypospadias [45].

7.4. Genital surgery

Surgery in minors with DSD is controversial, particularly in children raised female; it should focus on function and avoid tissue removal and irreversible procedures whenever possible, and many interventions are not medically necessary, justifying consideration of deferral to allow the individual's participation [2]. There are no controlled trials comparing surgical techniques or consensus on intervention timing [2]. Male options include hypospadias repair, orchidopexy, scrotoplasty, phalloplasty and Müllerian remnant removal; female options include clitoroplasty, vaginoplasty and urogenital sinus mobilisation, with vaginal dilatation as an alternative or adjunct [2]. Moderate or severe hypospadias repair is usually staged, between 12 months and 2 years or after toilet training, at 3–4 years; the complication rate requiring further surgery is 15–30%, and the child should not be circumcised because the foreskin may be needed for reconstruction [20]. The Oxford Desk Reference cites studies questioning childhood surgery and decisions without the individual's participation [3].

The 2006 consensus, now mainly of historical interest, allowed feminising surgery only for severe virilisation (Prader III to V), together with urogenital sinus correction, using an anatomical technique preserving erectile function and clitoral innervation; it acknowledged that the belief that cosmetic surgery in the first year alleviates parental distress and improves bonding lacked systematic evidence; retained early vaginal and urethral separation because of lack of contrary evidence; advised against vaginal dilatation before puberty and deferred vaginoplasty to adolescence, with the person motivated and participating; and considered there to be no evidence for prophylactic removal of asymptomatic utricular or Müllerian remnants [1]. The same document emphasised that there were no controlled trials of early (before 12 months) versus late surgery, clitoroplasty was associated with reduced sensitivity and tissue loss, a neovagina carried neoplasia risk and adult phalloplasty should be considered in initial counselling when male assignment depends on it, without creating unrealistic expectations [1]. In its legal appendix, it described Colombian Constitutional Court case law requiring “qualified and persistent” informed consent, granted in stages, and considering that parents cannot consent to surgery for children older than 5 years [1]. The subsequent European and Japanese recommendations summarised above are more restrictive regarding irreversible procedures in childhood [4, 5].

The 2016 global update divides DSD surgery into four components: the genital tubercle (reduction clitoroplasty or reconstruction by hypospadias repair or phalloplasty), Müllerian structures (connection of a vaginal cavity to the pelvic floor, vaginal replacement, dilation of a vaginal dimple or removal of Müllerian remnants), the gonads (orchidopexy, removal because of tumour risk or late virilisation, biopsy or preservation for reproduction) and perineoplasty [10]. In CAH, figure 2 of the article identifies three criteria for grading virilisation: the distance between the urethrovaginal confluence and the perineal surface, the length of the genital tubercle with the urethral tissue available to refashion the introitus, and fusion of the genital folds measured by the ratio of anogenital to anoclitoral distance [10]. A questionnaire on the most sensitive surgical situations, answered by 32 experts, mostly surgeons, reached no consensus on indications, timing, technique and outcome assessment; the levels of evidence of the answers were low (B and C), based mainly on team experience and on short, non-comparable series [10]. Most agreed on six points: reference centres with a multidisciplinary approach; a conservative approach to the gonads in complete androgen insensitivity; avoiding vaginal dilation in childhood; retaining asymptomatic Müllerian remnants during childhood, removable later if necessary; removing biopsy-confirmed streak gonads; and keeping 46,XY children with cloacal exstrophy in the male sex [10]. The document states that there is no evidence on the impact, on the person, the parents, society or the risk of stigmatisation, of treating or not treating DSD surgically in childhood [10].

In the ethical and legal dimension, the 2016 global update summarises nine principles: minimising physical and psychosocial risk; preserving fertility potential; respecting the person's right to participate in decisions; keeping options open by avoiding medically unnecessary irreversible treatments until there is capacity to consent; providing psychosocial and peer support; supporting healthy development of sexuality and gender identity; shared decision-making that respects the wishes and beliefs of the person and the parents; respecting the family and the parent–child relationship; and providing complete medical information appropriate to age, development and cognitive capacity [10]. It also recorded the increase in government initiatives, some of which condemn or call for a moratorium on elective genital surgery or gonadectomy without the person's own consent, court rulings against these practices for violating reproductive rights and bodily autonomy (Colombia, Australia, Kenya, South Carolina) and the possibility, in some jurisdictions (Australia, Germany, Malta), of deferring sex registration or registering it as “other”; it warns that the interpretation of these rights depends on the cultural and socio-economic context and that the legal trend is towards strengthening the person's autonomy [10].

The European consensus advises deferring sensitive or irreversible procedures, such as genital surgery, until the person can participate in the decision whenever possible, and notes that some countries, such as Germany, have adopted legislative recommendations to this effect; it proposes prospective registries recording complications, urinary and sexual function, appearance, quality of life and psychosexual functioning, and validated instruments such as HOPE, HOSE, PPS and SAGAS-M for masculinising surgery [4]. The Japanese guideline considers evidence insufficient to prefer early surgery decided by parents or deferred surgery until autonomy and suggests shared decision-making with the team (weak recommendation, expert opinion); it also suggests individualising feminising surgery timing and using techniques preserving neurovascular bundles (weak recommendations, very low evidence) [5]. Among 500 people with DSD aged 16 years or older who underwent genital or breast surgery in dsd-LIFE, 22% reported dissatisfaction with appearance, 20% with function and 13% marked dissatisfaction with both [5]. In the same cohort, 66% of people with CAH and 60% of people with XY DSD with prenatal androgen effects considered childhood the appropriate age for genital surgery; 47% of men preferred early hypospadias repair; only 12%, 11% and 21% (CAH, XY DSD with and without androgen effects) thought they would have been better off without any surgery, and the authors concluded that the data support case-by-case decisions rather than a general moratorium [46]. The authors themselves note that people operated on early more frequently approved early surgery and that perspectives varied by diagnosis, gender, surgical history and contact with support groups [46].

7.5. Gonadal management and germ cell tumour risk

Germ cell cancer risk varies by entity, age, gonadal location and possibly genetic predisposition; it is higher in gonadal dysgenesis, particularly early differentiation defects (SRY, WT1), than in ovotesticular DSD or disorders of hormone synthesis or action [4]. The expected precursor is germ cell neoplasia in situ (GCNIS) in gonads with testicular differentiation and gonadoblastoma in highly undifferentiated gonads; risk is considered greater in abdominal than inguinal or scrotal gonads [4]. The German guideline update lists Y chromosome material, gonadal location, degree of dysgenesis, age and genetic alterations such as TSPY expression or WT1 variants as risk factors, favouring individualised assessment, surveillance and deferred gonadectomy whenever clinically acceptable [19].

The 2016 global update identifies three parameters for estimating individual risk: genomic make-up (presence of the GBY region of the Y chromosome and of the candidate gene TSPY), expression of the embryonic germ cell markers OCT3/4 (POU5F1) and/or KITL (stem cell factor) beyond 1 year of age, and the anatomical location of the gonad [10]. Precursor lesions form in the embryonic or early postnatal period, but progression to invasive tumour occurs only during or after puberty, an argument frequently used to defer surgery [10]. Histology depends on the degree of testicularisation: carcinoma in situ/intratubular germ cell neoplasia unclassified (earlier names for GCNIS) in the dysgenetic testis, of higher risk, with Sertoli supporting cells (SOX9-positive), and gonadoblastoma in the dysgenetic gonad, of lower risk, with granulosa cells (FOXL2-positive), undifferentiated gonadal tissue being the earliest identifiable stage [10]. Diagnosis is the responsibility of an experienced pathologist, with immunohistochemistry and full knowledge of the clinical data, taking into account the physiological delay in germ cell maturation in young children or in the non-scrotal testis [10]. The highest risk prevalence (30–50%) is found in 46,XY gonadal dysgenesis and in some cases of 45,X/46,XY, with incomplete testicularisation and complete blockage of germ cell maturation, and a low EMS indicates a poorly differentiated gonad; in disorders of testosterone biosynthesis and action, the risk of carcinoma in situ in childhood is much lower (< 1–15%), with a limited tendency to invasive progression [10]. Next-generation sequencing, non-invasive screening by risk polymorphisms and serum microRNA markers were, at the time, awaiting validation [10].

Table 2 of the 2016 global update, clinical management of germ cell cancer risk; the approaches reflect the consortium's opinion in 2016 and should be read in the light of later European, Japanese and German recommendations, which favour surveillance and deferral where clinically acceptable [4, 5, 10, 19]. There are no data on the value or safety of cryopreservation when a precursor lesion is already present [10].

Table 4 of the Chicago consensus (2006), read in the original text; table 6 of the Japanese guideline reproduces the same values and management. “Gonadal dysgenesis” includes unspecified, 46,XY, 45,X/46,XY, mixed, partial and complete forms; “with Y” denotes positivity for the GBY region, including TSPY. Pubertal biopsy should allow examination of at least 30 seminiferous tubules, preferably with OCT3/4 immunohistochemistry. Denominators show that several estimates rely on one or two studies and a few dozen patients [1, 5].

The consensus text located the highest risk in TSPY-positive gonadal dysgenesis and partial insensitivity with intra-abdominal gonads, and the lowest (< 5%) in ovotesticular DSD and complete insensitivity, warning that unclear terminology and physiological delay of germ cell maturation complicated study interpretation [1]. Contemporary cohort data qualify this table. In dsd-LIFE, among 1040 adults, germ cell neoplasia was present in 12% of people with DSD and 14% of people with XY DSD; the highest risk (36%) occurred in 46,XY gonadal dysgenesis (33% in complete and 23% in partial forms), followed by mixed gonadal dysgenesis (8%) and complete androgen insensitivity (6%), with no cases in partial insensitivity, 46,XX testicular DSD, 46,XX CAH, Turner and Klinefelter syndromes or androgen synthesis defects [47]. In a US multicentre series of 83 operated patients, cited by the Japanese guideline, GCNIS or tumour was found in 9.6% (7 GCNIS and 1 invasive tumour), all in high- or intermediate-risk groups (15% of high-risk patients), with a median surgical age of 14 years in cases with lesions and no recurrence during a mean follow-up of 6.4 years [5]. GCNIS or tumour incidence in gonadectomies increases with age, accelerating between 15 and 20 years, and survival of patients with GCNIS resembles that of patients without lesions, unlike those already having invasive tumours [5]. In Turner syndrome with Y material, a Danish population study found gonadoblastoma in 7–10% [26].

Non-functioning streak and dysgenetic gonads should be removed; in a 46,XY child, absent virilisation with Müllerian structures indicates non-functioning gonads, which generally produce neither detectable AMH nor inhibin B, and very high infant FSH and LH are associated with non-functioning gonads [2]. An inguinal dysgenetic gonad with some function may be placed in the scrotum with surveillance; there are no surveillance guidelines, and one option is annual ultrasound [2]. Removal of gonads discordant with sex of rearing is controversial; potentially functioning gonads may be retained with surveillance, contrasexual puberty should be monitored and, if it occurs, may be suppressed with replacement of the desired hormone until the person can consent [2]. Given the lack of reliable tumour markers and imaging for precursor lesions, the European consensus considers it prudent to consider gonadal biopsies in late adolescence for most people with 46,XY or 45,X/46,XY DSD who retain gonads [4]. The Japanese guideline considers biopsy useful but without evidence for systematic use, suggests ultrasound, MRI and tumour marker surveillance in high-risk groups and acknowledges that prophylactic gonadectomy criteria are not established (weak recommendations, very low evidence); in prophylactic gonadectomies, only 40–50% of gonads had previously been identified by imaging [5]. In 45,X/46,XY, risk is low in a phenotypically normal boy with descended testes and higher if testes are impalpable [26]. The 2006 recommendations were more interventionist than current ones: testes in complete insensitivity and partial insensitivity raised female should be removed to prevent adult malignancy, with parents choosing early removal (also treating the hernia) or deferral to adolescence, considering that the earliest neoplasia described in complete insensitivity occurred at 14 years; the streak gonad in mixed gonadal dysgenesis raised male should be removed in early childhood, as should bilateral streak gonads in girls with gonadal dysgenesis and Y material; in androgen biosynthesis defects raised female, gonadectomy should precede puberty; and the scrotal testis in gonadal dysgenesis should be biopsied at puberty, with sperm cryopreservation and low-dose local radiotherapy if carcinoma in situ is present [1]. People with bilateral ovotestes were considered potentially fertile through functioning ovarian tissue [1]. For 17β-HSD3 deficiency, a shared decision-making sheet published in 2025 discusses early orchidectomy, eliminating discordant pubertal androgens and tumour risk but requiring pubertal induction and removing the person's participation, versus deferral [48].

7.6. Hormone therapy

Adrenal insufficiency. Some DSD require glucocorticoid and sometimes mineralocorticoid replacement, as in CAH. 46,XY people with a heterozygous pathogenic NR5A1 variant may require adrenal insufficiency assessment and treatment [2]. Hydrocortisone granules for children have different label doses: the US Alkindi Sprinkle® label recommends an initial replacement dose of 8–10 mg/m²/day, divided into three doses, allowing two doses in older children [49]; the European Alkindi® summary of product characteristics recommends 8–10 mg/m²/day for isolated adrenal insufficiency and 10–15 mg/m²/day for CAH, usually in three or four doses [50]. Both provide for temporary dose increases during stress (surgery, infection, trauma) [49, 50]; the US label indicates switching to parenteral corticosteroids with vomiting, severe illness or inability to take oral medication and lists growth retardation, Cushing syndrome and decreased bone mineral density with excessive doses [49].

Male puberty induction and maintenance. The Japanese guideline recommends testosterone to induce secondary sexual characteristics in hypogonadism (strong recommendation, low evidence), starting at a low dose: testosterone enanthate 25–50 mg every 4 weeks, with increases of 50–100 mg every 6–12 months, up to adult doses of 150–250 mg every 2–4 weeks over 2–3 years; lower starting doses favour height gain and higher doses pubertal progression [5]. The US testosterone enanthate label indicates replacement in primary or hypogonadotrophic hypogonadism (50–400 mg every 2–4 weeks) and, in delayed puberty, 50–200 mg every 2–4 weeks for a limited period, for example 4–6 months, with hand and wrist radiographs every 6 months because of advancing bone maturation [51]. The GeneReviews chapter on 46,XX testicular DSD describes, after 14 years, intramuscular testosterone enanthate every 3–4 weeks, starting at 100 mg and increasing by 50 mg every 6 months up to 200–400 mg, avoiding high starting doses because of the risk of priapism and avoiding oral androgens (methyltestosterone, fluoxymesterone) because of hepatotoxicity; contraindications include prostate or breast cancer [8]. Monitoring includes pre-injection testosterone every 3 months until optimised and then annually, haematocrit and, in adults, digital rectal examination and prostate-specific antigen at 3, 6 and 12 months and then annually, annual lipid profile and liver function, and bone densitometry every 3–5 years after puberty [8]. In dsd-LIFE, 78.1% of 197 people on testosterone reported satisfaction with treatment [5]. For male pubertal induction, the 2016 global update describes injectable testosterone esters every 1–4 weeks, with a regimen starting at 50 mg per month, increasing the dose every 6–12 months and reaching the full adult dose of 100 mg per week or 200 mg twice a month; the start is equal to or higher than that of the Japanese guideline (25–50 mg every 4 weeks), and the adult doses fall within the range of the US label (50–400 mg every 2–4 weeks) [5, 10, 51]. Injectable testosterone undecanoate, every 10–12 weeks, gives stable concentrations, but data in adolescents are limited; transdermal patches and gels give a more physiological daily exposure, with no evidence of superiority over injections, may not reach normal male values (gels) and are poorly accepted because of the frequency of application and pruritus (patches); there is also experience with testosterone implants, and topical DHT, where available, is being used in 5α-reductase deficiency, without well-documented efficacy [10]. Gonadotrophin-releasing hormone antagonists are being tried to delay contrasexual puberty in people with functioning gonads whose gender identity is uncertain or incongruent with gonadal hormones; in that case, hormone replacement and surgery should begin only after full psychological assessment, at the appropriate age and with the person fully informed [10]. In adulthood, the choice of hormones, doses and regimens should be tailored to the person's needs and optimise bone density, mental health, metabolic status, quality of life, sexual satisfaction and interest in fertility; optimal replacement after 50 years is not known: by analogy with symptomatic menopause, continuing oestrogens for about 5 years and then reducing is suggested, whereas men usually continue testosterone lifelong, with discussion of prostate risk; women on oestrogens require screening mammography and men on testosterone haematocrit, prostate examination and PSA according to national standards [10].

Testosterone before surgery and in micropenis. A short testosterone course may be used in infants with micropenis (stretched penile length below −2.5 standard deviations for age) [2]. The Japanese guideline suggests testosterone before hypospadias repair with a small phallus (weak recommendation, very low evidence): in a systematic review of 25 studies and 4094 patients, the most frequently reported intramuscular regimens were 2 mg/kg or 25 mg monthly, 2–3 months before surgery, with inconsistent effects on complications [5]. These paediatric regimens represent off-label use relative to the US label consulted, which does not cover infants or surgical preparation and recommends paediatric caution [51].

Oestrogen induction. The Japanese guideline recommends oestrogens to induce secondary sexual characteristics in female hypogonadism (strong recommendation, high evidence, derived mainly from Turner syndrome), with goals that include growth, uterine maturation, menstruation and bone mass, and asks for assessment of gender identity before starting; it recommends continuing oestrogens in adult women with Turner syndrome or with complete insensitivity after gonadectomy, to preserve bone mineral density [5]. When a uterus is present, a progestogen is added after puberty has progressed [2]; the 2006 consensus advised adding it after the first withdrawal bleed or after one to two years of continuous oestrogen and noted that there was no evidence of benefit from cyclical progestogen in women without a uterus [1]. The same consensus noted that people with partial androgen insensitivity may need supraphysiological doses of testosterone and that pubertal induction should reproduce normal maturation, including the growth spurt and the acquisition of bone mass, and serve as an opportunity to reinforce long-term treatment adherence [1]. The 2016 global update places pubertal induction usually between 10 and 12 years in girls and between 11 and 13 years in boys, according to maturity, wishes and the informed consent of the person and the parents, with the aim of reinforcing gender identity and promoting congruent secondary sexual characteristics, growth, bone health and psychosexual and social well-being [10]. In people with a female identity and a uterus, the standard regimen is low-dose oestrogen with a gradual increase over 2–3 years, reproducing the normal tempo of puberty, with especially slow titration when height is a concern, as in Turner syndrome [10]. Ooestradiol, measurable in serum to adjust the dose, is preferred to equine or synthetic oestrogens: oral oestradiol (0.5–2.0 mg/day) has highly variable bioavailability, and transdermal oestradiol, which avoids hepatic first pass and allows oestradiol to be titrated to the middle of the normal range for the Tanner stage, starts at 6 μg/day and increases gradually over 3 years to 25–100 μg/day, according to oestradiol levels and clinical response [10]. After 1–3 years of oestrogen, or with breakthrough bleeding, medroxyprogesterone acetate 5–10 mg/day or micronised progesterone 200 mg/day for 10–14 days per month is added in people with a uterus; without a uterus, the oestrogen increase follows the same pattern and no progestogen is needed [10]. Some women combine testosterone with oestrogen, with no clinical trial results available at the time [10].

7.7. Fertility

Fertility is greatly reduced in almost all DSD; germ cells are absent or markedly reduced in most gonads, and early tissue cryopreservation is available only for a limited number of patients, while in vitro maturation of immature gametes and derivation of germ cells from induced pluripotent stem cells are not yet clinically available [4]. Microdissection testicular sperm extraction may be an option for some azoospermic men; women with 46,XY DSD and a uterus have achieved pregnancies with oocyte donation; and in 2015 the first births after uterine transplantation in women with MRKH syndrome were reported [2, 4]. Some NR5A1 variants allow testicular development and fertility, possibly with medically assisted reproduction [2]. In 46,XX testicular DSD, insemination with donor sperm is the option for the couple [8]. The Japanese guideline suggests assisted reproduction techniques with ejaculated or testicular sperm and fertility preservation in premature ovarian insufficiency when residual follicles are present, acknowledging the lack of a reliable method to detect them (weak recommendations) [5]. The 2016 global update mentions sperm extraction with intracytoplasmic sperm injection (ICSI) in people with functioning gonads who do not need testosterone at puberty, as in 45,X/46,XY mosaicism, 5α-reductase deficiency and partial insensitivity, and also in those requiring hormone replacement, if germ cells are present; in women, ovulation stimulation and embryo transfer from donated oocytes have been used, including in CAH and Turner syndrome [10]. Decisions on gonadal surgery may be staged to weigh experimental fertility preservation against tumour risk or unwanted hormone production [4].

7.8. Transition and adult care

Adolescents frequently have difficulty accessing specialist adult care and drop out of follow-up; early involvement of the adult specialist, open review of all clinical data and a DSD-specific transition checklist are recommended [4]. The Japanese guideline suggests transition with multidisciplinary care and psychological support (weak recommendation, expert opinion) [5]. The 2016 global update notes that, with exceptions, poor adherence or disengagement from services has no short-term consequences but exposes the person to osteoporosis, gonadal malignancy and poorer psychosocial and psychosexual adjustment; concealment of elements of the medical history and negative medical experiences contribute to loss to follow-up [10]. It adds anticipatory anxiety about romantic and sexual relationships, linked to atypical genital anatomy or function or to infertility, and fear of stigmatisation, recommends developmentally adapted education and proposes reintroducing contact with support groups to adolescents who initially declined it [10]. In the absence of DSD-specific guidelines, adult hormone replacement usually follows the recommendations published for Turner and Klinefelter syndromes [4].

7.9. Registered studies and recent developments

There is no drug therapy targeting DSD as a group or randomised trials on surgery timing; active studies mainly concern observation or organisation of care.

These studies have small samples, non-comparative designs and, for dsd-LIFE, a cross-sectional design with overrepresentation of Turner and Klinefelter syndromes and CAH and recruitment difficulties in XY DSD, limiting extrapolation [18]. Registry NCT05867979 had no results published in the registry at the consultation date. In the last 12 months, peer-reviewed publications identified included the Japanese guideline in English (January 2026) and the summary of tumour risk recommendations from the German guideline update (September 2026) [5, 19]. No authorisation applications or regulatory opinions targeting DSD as a general group were identified in the sources consulted.

8. Reproductive Options and Family Counselling

Counselling becomes precise only after the specific diagnosis; the Oxford Desk Reference summarises the rule as “counsel for the specific diagnosis” for recurrence risk, carrier detection and prenatal diagnosis [3]. In 46,XY and 46,XX gonadal DSD, sex-limited expression creates patterns mimicking reduced penetrance: an autosomal dominant variant may be transmitted by an unaffected 46,XX mother or a mildly affected father, and an apparently negative family history can be confirmed only after adequate assessment of relatives [2].

When the variant is not found in parental leucocytes, parental mosaicism should be considered, and leucocyte testing does not detect exclusively germline mosaicism [2]. Reports of cryptic SRY translocations present in gonads but not blood complicate risk calculation in 46,XX testicular DSD [8]. The ideal time to discuss risk and prenatal or preimplantation testing is before pregnancy; when the familial cause is identified, both are possible, and differences in professional and family perspectives on their use should be acknowledged [2, 8]. DNA banking should be considered for an index case without a molecular diagnosis, as techniques and knowledge will continue to evolve [2].

In a pregnancy with no known risk, suspicion usually arises from discordance between karyotype or non-invasive prenatal screening and ultrasound sex; an SRY-positive result in a 46,XX fetus lowers, without excluding, the probability of ambiguous genitalia, and the difficulties include the uncertain reliability of genital ultrasound, phenotypic variability and the impossibility of excluding all causes prenatally [8]. In prenatally diagnosed 45,X/46,XY mosaicism, the ascertainment bias of the postnatal literature should be explained: of 76 cases of true mosaicism in amniotic fluid, 75 were phenotypically male and 72 (95%) had normal male genitalia, and in a review of 47 cases with phenotypic information 89.4% had an apparently normal male phenotype [26]. Management includes detailed anomaly ultrasound (genitalia, hygroma, heart), sensitive discussion of options, postnatal confirmation and referral to paediatric endocrinology [26]. When a sex chromosome aneuploidy is diagnosed prenatally, the Oxford Desk Reference recommends discouraging hasty decisions and disclosing the child's karyotype on a need-to-know basis [34]. Prenatal dexamethasone to prevent virilisation of female fetuses with CAH remains controversial, with concerns about effects on working memory in children exposed in the first trimester [4, 27].

9. Special Considerations: Population Diversity and Epidemiology

Frequency estimates vary with definition: including mild hypospadias and cryptorchidism or only expert-confirmed genital ambiguity changes the order of magnitude. The following figures measure different entities and should not be added together.

Proportions by subgroup also depend on the centre. Among children with atypical genitalia, COST Action DSDnet cites 75% 46,XY, 10–15% 46,XX and the remainder with sex chromosome abnormalities [7]; the Japanese guideline compiles 51–81% 46,XY, 18–30% 46,XX and 1–8% sex chromosome DSD, with CAH accounting for 65–74% of 46,XX DSD and a definitive diagnosis in only 24–59% of 46,XY DSD [5]. Délot and Vilain estimate about 15% chromosomal DSD [21]. According to the 2016 global update, CAH and mixed gonadal dysgenesis account for about half of DSD presenting with genital ambiguity, only a small fraction of DSD require extensive multidisciplinary assessment to recommend a sex of rearing, and global estimates include Klinefelter syndrome (1 in 500 to 1 in 1000 live births) and Turner syndrome (about 1 in 2500) [10]. The proportion of CAH among 46,XX DSD differs according to the denominator: 90–95% when 46,XX DSD with atypical genitalia or monogenic forms are considered [7, 21] and 65–74% in the atypical genitalia series compiled by the Japanese guideline, which include other causes of 46,XX DSD [5]. In the German registry, more than 50% of children had no definitive diagnosis at 6 months, early surgery was frequent even without a diagnosis and integrated psychosocial care was exceptional [30].

Genetic frequency data come mainly from specialist centre cohorts rather than from populations. Eggers' international cohort included patients from Australia, New Zealand, Europe and several Asian countries [11]; the Brazilian cohort of 209 46,XY index cases from a São Paulo referral centre found a molecular diagnosis in 59.3%, with DHX37 and NR5A1 as the most frequent causes in gonadal dysgenesis and in DSD of unknown clinical aetiology, respectively [12]; and the Chinese series cited by the Japanese guideline show high proportions of variants in AR, SRD5A2 and NR5A1 [5]. dsd-LIFE recruited in six European countries, with over-representation of conditions not usually described as DSD, such as Turner and Klinefelter syndromes and CAH, and with greater difficulty in recruiting people with XY DSD [18]. Table 1 of the 2016 global update lists support and advocacy groups from Africa, Asia, Oceania, Europe and the Americas, including, in South America, groups of people with androgen insensitivity in Argentina and Colombia and an MRKH syndrome group in Chile, and, in the United States, organisations such as Accord Alliance, the AIS-DSD Support Group, the CARES Foundation and InterACT; it includes no groups based in Portugal or Brazil [10]. No population-based epidemiological data from Portugal or Brazil for the DSD group were found in the sources consulted; from Portugal, a clinical case report from Porto was consulted (section 10.2) [57].

10. Illustrative Clinical Case

10.1. Newborn with 45,X/46,XY mosaicism and atypical genitalia (Poland, 2025)

Krzyścin and colleagues, from Szczecin, described a child seen at 10 weeks of life for atypical genital development, registered female by the parents [36]. During pregnancy, first-trimester screening showed generalised fetal oedema and nuchal translucency of 3.5 mm, with high trisomy 21 risk; amniocentesis at 16 weeks revealed 45,X/46,XY mosaicism, and the 20-week ultrasound showed ambiguous genitalia (Figure 1 — ultrasound at 20 weeks) [36]. Oedema regressed, and the child was born at 39 weeks and 6 days by caesarean section, weighing 2900 g and measuring 53 cm, with facial dysmorphism and a webbed neck [36]. External genitalia showed a left hemiscrotum with a palpable gonad, no palpable gonad on the right with incomplete fold differentiation, and a urethral meatus at the base of a phallus measuring 2 cm long and 1.3 cm wide (Figure 3 — external genitalia) [36].

On day 7, testosterone was 1.21 ng/mL, with LH 4.3 IU/L and FSH 2.1 IU/L, AMH 14.6 ng/mL, oestradiol below 5 pg/mL and 17OHP 36 ng/dL; the authors interpreted the profile as compatible with male minipuberty and considered AMH reduced, and CAH screening was normal [36]. Persistently elevated TSH (28–33 μIU/mL) with normal free thyroid hormones and heterogeneous thyroid ultrasound led to a diagnosis of congenital hypothyroidism and levothyroxine; echocardiography showed aortic coarctation [36]. Pelvic ultrasound showed neither uterus nor ovaries, identified a 0.6 mL left scrotal testis and a right inguinal canal testis with dysplasia signs; MRI confirmed absence of Müllerian structures [36]. Lymphocyte karyotyping (20 metaphases) showed 45,X in 50%, 46,XY with translocation of a Yp11.3 fragment to an autosome in 30%, and an unidentified marker chromosome in 20%; FISH in buccal mucosal cells (DXZ1, DYZ3 and SRY probes) showed 46% of cells with X signal alone, 48% with X, Y and SRY, and 6% with a marker of indeterminate SRY status; a skin biopsy from the neck fold confirmed tissue mosaicism [36].

The gynaecology, urology and endocrinology team proposed male rearing at that stage, presented to the parents as a proposal, but the parents decided to register the child female [36]. Urography and abdominopelvic MRI were planned, with consideration of removal of the dysgenetic right gonad and biopsy of the left; the family received psychological and endocrine follow-up of sex development and gender identity [36]. The authors emphasise that Polish law allows only binary sex classification, pressuring early decisions [36]. The case illustrates several points of this article: prenatal discordance; the need to test more than one tissue in mosaicism; the value of the minipuberty window for assessing testicular function; coexisting Turner features (webbed neck, coarctation) requiring cardiovascular and growth surveillance; and asymmetrical gonadal management. The reported management concerns a specific case and does not replace general recommendations; the reference to a 15–35% germ cell tumour risk in the authors' text corresponds to the group with gonadal dysgenesis with Y and an intra-abdominal gonad, not this child's scrotal testis (section 7.5) [5, 36].

10.2. Adult with SRY-positive 46,XX testicular DSD (Porto, 2024)

A 24-year-old man was seen at an endocrinology service in Porto for erectile dysfunction of approximately one year's duration, reduced libido, bilateral gynaecomastia and mood and sleep complaints [57]. He measured 162 cm and weighed 69 kg, had typical secondary sexual characteristics and penis (7.9 cm at rest) and bilateral 6 mL testes [57]. Tests showed hypergonadotrophic hypogonadism (FSH 30.81 mIU/mL, LH 11.04 mIU/mL, total testosterone 1.56 ng/mL), azoospermia confirmed in two samples and lumbar and femoral osteopenia [57]. Karyotype was 46,XX.ish ins(X;Y)(SRY+), with FISH locating SRY on the short arm of one X; the patient declined testicular biopsy [57]. A testosterone ester mixture (Sustenon®), at a stable dose of 250 mg every 4 weeks, improved libido, erectile function and bone mineral density, and the couple chose in vitro fertilisation with donor sperm [57]. The case matches the typical postpubertal phenotype described in GeneReviews and demonstrates the test sequence: conventional karyotyping followed by metaphase SRY FISH to localise the translocation [8].

11. Prognosis and Long-Term Follow-up

Prognosis depends on the entity: immediate life-threatening risk concentrates in forms with adrenal insufficiency, while long-term morbidity involves gonadal function, fertility, tumour risk, bone and metabolic health and mental health. In dsd-LIFE, WHOQOL-BREF quality of life was similar to reference European populations in the psychological domain, slightly worse physically, slightly better environmentally and lower in social relationships; health status was the main predictor, and diagnosis added little explained variance [67]. The European consensus emphasises that many adult issues remain unanswered because of a lack of data on the late course of different conditions [4].

Loss to follow-up at transition is frequent, so the European consensus proposes predefined schedules and a personal clinical history summary to facilitate transfer between clinics [4]. Standardised data collection in registries such as I-DSD and I-CAH is presented as a prerequisite for generating outcome evidence [4, 7].

12. Summary and Final Considerations

DSD comprise congenital conditions in which chromosomal, gonadal or anatomical sex develops atypically. Since the Chicago consensus, classification starts with karyotype (sex chromosome, 46,XY and 46,XX DSD) and replaces terms considered stigmatising; differences is now frequent, but in dsd-LIFE most participants accepted or were neutral towards disorders and preferred the specific name of their condition [1, 16]. In newborns with atypical genitalia, the initial sequence combines clinical and laboratory work in parallel: objectively scored examination, rapid chromosomal sex determination, ultrasound, blood glucose, electrolytes and 17OHP with attention to physiological timing, sample collection before corticosteroids and careful communication without assigning sex before assessment [5, 9]. Second-tier investigations use AMH, hCG testing, steroids by mass spectrometry and imaging, and genetic testing integrates karyotyping, CNV and panels or exome sequencing, with yields of 40–60% in 46,XY DSD and recognised limitations for regulatory variants, tissue mosaicism and variants of uncertain significance [7, 11, 12, 21].

Management is multidisciplinary and longitudinal. The main divergences between documents concern the timing of genital surgery and gonadectomy: the European consensuses and the German guideline tend to defer irreversible interventions when clinically acceptable, the Japanese guideline recommends shared decision-making owing to the lack of comparative evidence, and the adults surveyed in dsd-LIFE do not support a general moratorium [4, 5, 19, 46]. The 2016 global update recorded the lack of consensus among surgeons, with level B and C evidence, and the legal trend towards strengthening the person's autonomy and deferring medically unnecessary irreversible interventions [10]. Tumour risk is concentrated in gonadal dysgenesis with Y material and is low in several disorders of hormone synthesis or action [5, 47]. The most relevant gaps remain adult outcomes, comparative evidence on surgery and gonads, and the molecular diagnosis of about half of 46,XY DSD [4, 21].

13. References

1. Hughes IA, Houk C, Ahmed SF, Lee PA; LWPES Consensus Group; ESPE Consensus Group. Consensus statement on management of intersex disorders. Arch Dis Child. 2006;91(7):554-63. doi:10.1136/adc.2006.098319. PMID: 16624884.
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