Hirschsprung Disease

Literature and regulatory information updated: 6 October 2026.

Congenital intestinal aganglionosis (aganglionic megacolon; HSCR) — isolated oligogenic/multifactorial disease, with RET as the principal locus, and associated syndromic and chromosomal forms (Waardenburg–Shah, Mowat–Wilson, Haddad, trisomy 21 and others)

0. Initial Reference Table

1. Introduction

Hirschsprung disease is the most important genetic cause of functional intestinal obstruction in neonates and infants [1, 8]. It is characterised by the absence of neural crest-derived enteric ganglion cells throughout a variably extensive intestinal segment that always begins in the distal rectum and extends proximally in continuity [1, 2]. Enteric ganglia share their neural crest origin with melanocytes, adrenal medullary cells, thyroid C cells and part of the autonomic nervous system; the disease is therefore classified as a neurocristopathy and brings together paediatric surgery, gastroenterology, endocrine cancer genetics and dysmorphology [2].

The modern history of the disease began in Berlin in 1886, when Harald Hirschsprung, professor of paediatrics in Copenhagen, presented two infants who had died with constipation from birth and colonic dilatation and hypertrophy; his account was published in 1888 in the Jahrbuch für Kinderheilkunde [15]. The first child died at 11 months with sepsis after a period of diarrhoea, a presentation now recognised as toxic megacolon and enterocolitis; in the second, rectal examination revealed an empty rectum without stenosis [15]. For approximately 60 years, colonic dilatation was considered the primary malformation. Only in 1948 did Zuelzer and Wilson describe 11 patients with proximal megacolon associated with a nondilated, aganglionic distal colon; Swenson and Bill demonstrated spasm of the distal segment in 20 patients using a low-pressure contrast enema; and Whitehouse and Kernohan documented the absence of ganglion cells in the distal colon of 11 patients, with abundant unmyelinated nerve fibres [15]. In 1949, Bodian and colleagues distinguished, among 73 cases of megacolon, 39 with clinical and pathological evidence of Hirschsprung disease from 34 with idiopathic megacolon [15].

Surgical treatment followed understanding of the pathophysiology. Swenson and Bill showed that excision of the contracted segment and anastomosis of the innervated colon to the anus provided definitive treatment; Duhamel developed a transanal retrorectal pull-through with a side-to-side anastomosis (1956), Rehbein a modified anterior resection, and Soave an endorectal pull-through. In 1998, De la Torre-Mondragón and Ortega-Salgado described the exclusively transanal approach, followed by laparoscopic variants [15].

Understanding of the genetics developed from epidemiological observations. In 1990, Badner and colleagues studied 487 probands, confirming male predominance (3.9:1) and a sibling risk of 4% against a population incidence of 0.02%. Complex segregation analysis showed that extensive disease was consistent with a dominant gene with incomplete penetrance, whereas short-segment disease fitted a multifactorial or very-low-penetrance recessive model [7]. In 1994, two groups simultaneously published Nature reports of RET proto-oncogene variants in patients with Hirschsprung disease: Edery and colleagues (Hospital Necker-Enfants Malades) described nonsense and missense variants in exons 2, 3, 5 and 6 that segregated with the disease, and Romeo and colleagues (Istituto Gaslini) identified four variants in the tyrosine kinase domain [16, 17]. In the same year, Puffenberger and colleagues identified the endothelin B receptor (EDNRB) variant p.Trp276Cys in a Mennonite pedigree, with dose-dependent risk [18]. In 2005 and 2010, Chakravarti's group demonstrated that a common noncoding variant in a RET intron 1 enhancer contributes most of the population risk [19, 20]; in 2019, analysis of exomes, regulatory variants and copy-number variants identified a genetic factor in 72.1% of patients [8].

GeneReviews provided an overview chapter between 2002 and 2015, now retired and retained solely as a historical reference; data from that text are identified as historical here and compared with more recent sources [2]. European clinical practice is guided by ERNICA recommendations, published in 2020 and updated using GRADE methodology in the 2025 version, published in 2026 [3, 10].

2. Molecular Genetics and Pathophysiology

2.1. Embryology and tissue mechanism

Vagal neural crest cells migrate craniocaudally and colonise the intestinal wall between the fifth and twelfth weeks of gestation; interruption of this colonisation leaves the most distal segment without enteric plexuses. This always includes the rectum and, depending on when migration ceases, progressively greater lengths of colon and small intestine [1]. The aganglionic segment lacks coordinated peristalsis and reflex relaxation, producing functional obstruction; the innervated bowel proximal to it dilates and hypertrophies, explaining the megacolon [2, 15]. Increased acetylcholinesterase activity reflects the hypertrophic extrinsic cholinergic nerve fibres in the aganglionic segment [3, 10]. A variably long and sometimes asymmetric transition zone between normal and aganglionic bowel exhibits hypoganglionosis and functional abnormalities; surgical resection therefore extends beyond the first level containing normal ganglion cells [2, 10].

2.2. Genetic architecture of isolated disease

Isolated Hirschsprung disease has heritability exceeding 80% and is considered an oligogenic malformation with RET as the principal locus [1, 8]. The model comprises three variant classes: common noncoding variants with low individual risk, rare coding variants with incomplete penetrance, and structural or chromosomal variants with large effects [8]. The dominant pathways are RET signalling (with the ligands GDNF and NRTN and coreceptor GFRA1) and endothelin signalling (EDNRB, EDN3, ECE1), with epistatic interactions between them; neuregulin (NRG1, NRG3) and class 3 semaphorin (SEMA3C, SEMA3D) pathways also contribute [2, 8].

Tilghman and colleagues' study (New England Journal of Medicine, 2019) analysed 190 patients of European ancestry using exome sequencing, genotyping and copy-number analysis. Five or more risk alleles in four noncoding elements (three in RET: rs2435357, rs7069590 and rs2506030; one in the SEMA3 cluster: rs11766001) were present in 48.4% of patients and 17.1% of controls (odds ratio [OR] 4.54; 95% CI 3.19–6.46) [8]. Rare coding variants in 24 genes involved in enteric neural crest cell differentiation, seven newly implicated (ACSS2, ADAMTS17, ENO3, FAM213A, SH3PXD2A, SLC27A4, UBR4), occurred in 34.7% of patients and 5.0% of controls (OR 10.02; 95% CI 6.45–15.58); large structural variants or chromosomal abnormalities occurred in 11.4% versus 0.2% (OR 63.07; 95% CI 36.75–108.25), half being trisomy 21 [8]. At least one genetic risk factor was identified in 72.1% of patients, and at least 48.4% had a structural or regulatory RET deficiency; considering the RET regulatory network (the gene itself, transcription factors RARB, GATA2 and SOX10, ligands and coreceptor), pathogenic alleles were found in 63.2% [8]. The three variant classes had population-attributable fractions of 37.7%, 31.1% and 11.3% (total 61.9%) [8].

One finding contrasted with the classical literature: only 6.3% of patients (12/190) had pathogenic RET coding variants, compared with approximately 50% in older series. The authors attributed this difference to differing definitions of pathogenicity and overrepresentation of severe and familial cases in earlier series [8]. The EDNRB pathway contributed to 4.2% of cases [8]. Other sources report RET coding variants in 40–50% of familial and 15–20% of sporadic cases (OXF; ATA 2015), approximately 50% of familial and 35% of simplex cases (Smith; GeneReviews MEN2), 15–35% of sporadic and up to 50% of familial cases (ERNICA), and, in the retired GeneReviews chapter, 17–38% of short-segment, 70–80% of long-segment and 50% of familial disease, and 3–10% (10–35% in some referral series) of simplex cases [1, 2, 10, 14, 21, 22]. These wide estimates depend on the study population, extent of aganglionosis and classification criteria, and should not be presented as genetic test sensitivity.

2.3. RET and the regulatory variant rs2435357

RET (10q11.21; MANE Select transcript NM_020975.6) encodes a transmembrane receptor tyrosine kinase for GDNF-family ligands, requiring a GFRA coreceptor for activation and directing enteric nervous system and kidney development [5, 9]. Loss-of-function variants causing Hirschsprung disease are distributed throughout the coding sequence, without a hotspot, and include microdeletions and insertions, nonsense or missense variants, splice variants and deletions of gene segments; more than 100 have been described [1, 14]. Many mutant proteins are retained in the endoplasmic reticulum and fail to reach the cell surface, reducing signalling [22]. Deletions of 10q11.2 encompassing RET support the haploinsufficiency model [2].

The rs2435357 variant lies in the MCS+9.7 enhancer within RET intron 1. In 690 probands of European and 192 of Chinese ancestry, Emison and colleagues (2010) demonstrated that the T allele, described in the literature as resulting from a C→T substitution, confers more than fourfold susceptibility and disrupts a SOX10-binding site, impairing RET transactivation [20]. T-allele frequencies were 20–30% in controls and 54–62% in cases of European ancestry, and 47% and 88%, respectively, in those of Chinese ancestry [20]. The allele is more frequent in common presentations (male, short-segment, simplex families), whereas rare and multiple coding variants predominate in less common, more severe presentations (female, long-segment, multiplex families); the T allele also increases penetrance in carriers of rare coding variants [20]. The authors proposed a “cellular recessive” model in which disease arises when both RET alleles have impaired function through coding variants, regulatory variants or both [1, 20]. In 2005, the same group had shown that this variant has low penetrance, different genetic effects in males and females, and a contribution to risk 20 times greater than that of rare alleles [19]. In a study of 376 European families, risk varied more than 30-fold between individuals without susceptibility alleles and those carrying up to six alleles in RET and SEMA3 [23].

In HGVS nomenclature, the position of rs2435357 corresponds to NC_000010.11:g.43086608T>C and NM_020975.6:c.73+9277T>C [9]. Because the GRCh38 reference sequence carries a T at this position, the HGVS description c.73+9277T>C denotes the change to the C allele; the risk-associated allele described by Emison and colleagues is T [9, 20]. This apparent inversion between the reference notation and the «C→T» orientation used in the association literature should be made explicit in reports to avoid misinterpretation.

2.4. Allelic relationship with multiple endocrine neoplasia type 2

The same RET gene causes, through germline gain-of-function variants, multiple endocrine neoplasia type 2 (MEN2) [22]. Exon 10 cysteine variants at codons 609, 611, 618 and 620 are associated simultaneously with MEN2A or familial medullary thyroid carcinoma and with Hirschsprung disease [14, 22]. In patients with MEN2A and Hirschsprung disease, the codon distribution is 609 (15%), 611 (5%), 618 (30%) and 620 (50%); Hirschsprung disease occurs in about 7% of patients with MEN2A and, conversely, 2–5% of patients with Hirschsprung disease have MEN2A [14]. The accepted explanation is that constitutive activation is sufficient for neoplastic transformation of C cells and chromaffin cells, whereas the reduced cell-surface expression of RET is insufficient for the trophic response of enteric neuronal precursors [14]. Activating variants are present in about 2–3% of sporadic cases of Hirschsprung disease according to ERNICA, and the retired GeneReviews chapter estimated 2.5–5% in some series [2, 10]. In MEN2B (variant NM_020975.6:c.2753T>C p.(Met918Thr) in more than 90% of cases), neonatal intestinal obstruction may mimic Hirschsprung disease but results from diffuse ganglioneuromatosis, with thickening of the myenteric plexuses and ganglion cell hypertrophy; true coexistence of Hirschsprung disease and MEN2B has been described in only one case [2, 21].

2.5. Endothelin pathway: EDNRB, EDN3 and ECE1

Endothelin 3, acting through the B receptor (EDNRB, 13q22.3, MANE NM_001122659.3), prevents premature differentiation of melanocyte and enteric neuron precursors during a critical developmental window; its loss leaves the skin, hair, iris and cochlear stria vascularis without melanocytes and the distal intestine without ganglia [5]. Genetic behaviour is dose-dependent: in general, homozygosity for EDN3 or EDNRB variants causes Waardenburg syndrome type 4, whereas heterozygotes present with isolated Hirschsprung disease, although this correlation does not always hold [1, 2]. In the Pennsylvania Mennonite kindred, the EDNRB p.Trp276Cys variant conferred a risk of 74% in homozygotes and 21% in heterozygotes [18]. In the MANE transcript, this variant corresponds to NM_001122659.3:c.828G>T, NP_001116131.1:p.(Trp276Cys) [9]. EDNRB was associated with 3–7% and EDN3 with about 5% of cases of non-syndromic Hirschsprung disease in the retired GeneReviews chapter, and EDNRB with about 5% according to ERNICA [2, 10]. ABCD syndrome (albinism, black lock, cell migration disorder of the neurocytes of the gut, deafness), associated with a homozygous nonsense EDNRB variant, was considered by its authors to be an expression of Waardenburg–Shah syndrome rather than a separate entity [5]. The association of ECE1 with Hirschsprung disease with cardiac defects and autonomic dysfunction (OMIM 613870) rests on a single patient with a variant whose population frequency is not compatible with a fully penetrant dominant allele; it should be interpreted, at most, as a possible contributor [5].

2.6. Genes underlying syndromic forms

SOX10 (22q13.1, MANE NM_006941.4) encodes a transcription factor expressed in neural crest cells from their exit from the neural tube throughout intestinal colonisation; it activates MITF synergistically with PAX3 and regulates RET and EDNRB [2, 5, 8]. Heterozygous variants cause Waardenburg syndrome type 4C, either de novo or dominantly inherited, and have not been described in isolated Hirschsprung disease [2]. Truncating variants whose messenger RNA escapes nonsense-mediated decay produce proteins with a dominant-negative effect and the more severe PCWH phenotype (peripheral demyelinating neuropathy, central dysmyelinating leukodystrophy, Waardenburg syndrome and Hirschsprung disease); variants triggering such decay produce the restricted Waardenburg–Shah phenotype [24].

ZEB2 (2q22.3, MANE NM_014795.4) encodes a transcriptional repressor (SIP1, SMAD-interacting protein); haploinsufficiency through deletions or truncating variants causes Mowat–Wilson syndrome, and the murine protein interacts with Sox10 during enteric nervous system development [25, 26]. Large deletions are associated with more severe phenotypes and longer aganglionic segments [26].

PHOX2B (4p13, MANE NM_003924.4) causes congenital central hypoventilation syndrome, the extreme expression of autonomic nervous system dysregulation; expansions of the second polyalanine tract in exon 3 (genotypes 20/24 to 20/33) act through dominant-negative or toxic mechanisms, while nonpolyalanine variants and deletions primarily cause loss of function [5, 27]. In its association with Hirschsprung disease (Haddad syndrome), RET acts as a modifier gene [2].

Other genes underlying syndromic forms include KIFBP (formerly KIAA1279, autosomal recessive Goldberg–Shprintzen syndrome), L1CAM (X-linked L1 syndrome), TCF4 (Pitt–Hopkins syndrome), RMRP (cartilage–hair hypoplasia), DHCR7 (Smith–Lemli–Opitz syndrome) and ELP1 (familial dysautonomia) [1, 2].

2.7. Modifiers and new loci

A 2025 multiancestry genome-wide association study, comprising 1,250 cases and 7,140 controls, identified four new susceptibility loci (JAG1, HAND2 and ZNF25 reaching genome-wide significance, and UNC5C prioritised for functional relevance) and developed an 11-polymorphism polygenic risk score with comparable performance across ancestries [28]. Tilghman and colleagues interpreted male predominance as a property of the disease rather than of a specific gene, since ORs were consistently higher in males without significant differences by variant class [8]. The incomplete penetrance of most variants implies that stochastic, environmental or epigenetic factors also contribute [8].

3. Clinical Spectrum and Manifestations by System

3.1. Neonatal gastrointestinal presentation

Approximately 90% of patients present in the neonatal period [10]. Classical symptoms are abdominal distension (more than 90%), vomiting, which may be bilious (more than 85%), and failure to pass meconium within the first 24 hours of life (more than 60%) [10]. The retired GeneReviews chapter reported failure to pass meconium within the first 48 hours in 50–90% of affected neonates, alongside constipation, abdominal pain and occasional diarrhoea [2]. In the population-based United Kingdom and Ireland cohort (305 infants with histologically confirmed disease, born between October 2010 and September 2012), 91.5% presented and 83.9% were diagnosed during the neonatal period, but only 23.9% and 44.2% had passed meconium within 24 and 48 hours, respectively. Thus, almost half passed meconium within 48 hours, and early passage does not exclude the diagnosis [6]. Rectal examination or insertion of a rectal tube characteristically produces explosive passage of gas and stool, sometimes foul-smelling, and plain radiography shows dilated loops suggesting distal obstruction [10]. Some patients already have enterocolitis at presentation [10].

In a systematic review cited by ERNICA, only 5% of 4,127 infants diagnosed between 1964 and 2013 were preterm, rising to 14% among those born in more recent years [10]. Contemporary series indicate that presentation after three years of age is uncommon, but diagnosis may occur later in childhood or even adulthood; the disease should therefore be considered in severe lifelong constipation [2, 10].

3.2. Hirschsprung-associated enterocolitis

Hirschsprung-associated enterocolitis (HAEC) is the principal cause of severe morbidity and death in these patients [13]. Reported incidence ranges from 6% to 60% before definitive surgery and from 25% to 37% afterwards, reflecting the absence of a standardised definition [13]. ERNICA estimates that approximately 30% experience at least one postoperative episode [10]. Predisposing factors include a family history of Hirschsprung disease, long-segment disease, trisomy 21, previous enterocolitis and any residual obstruction (retained aganglionosis, transition-zone pull-through, anastomotic stricture, twisted pull-through or a tight muscular cuff after Soave surgery) [10, 13]. Proposed mechanisms include dysbiosis, impaired mucosal barrier, altered innate immune responses and bacterial translocation [13]. Classical manifestations are abdominal distension, fever and diarrhoea, with possible vomiting, rectal bleeding, lethargy and constipation; mild disease can be mistaken for viral gastroenteritis [13]. Intestinal perforation is a potentially lethal complication [2].

3.3. Associated anomalies

According to OXF, approximately 5% of patients have cardiac malformations, predominantly atrial or ventricular septal defects, 4% renal dysplasia or agenesis, and 2–3% genital anomalies such as hypospadias [1]. Excluding trisomy 21, the retired GeneReviews chapter reports central nervous system anomalies in 3.6–3.9%, congenital cardiac malformations in 2.3–4.8%, gastrointestinal anomalies (malrotation, imperforate anus, Meckel diverticulum, sacrorectal fistula) in 3.3–3.9%, and genitourinary anomalies (cryptorchidism, inguinal hernia, hypospadias, renal malformations, urethral fistula) in 5.6–7.3% [2]. The ERNICA 2025 update cites congenital anomalies of the kidney and urinary tract in approximately 22%, with approximately 7% requiring medical or surgical intervention, predominantly renal dysplasia or hypoplasia, hydronephrosis and vesicoureteral reflux, and cardiac comorbidity in 6–10% [3]. In the British cohort, 23% of infants had an associated anomaly and 15% a recognisable syndrome [6]. ERNICA estimates that 4–30% have an associated developmental disorder or syndrome [10].

3.4. Nutritional status

In a multicentre study cited by ERNICA, approximately 16% of children had moderate-to-severe malnutrition on admission for surgery. A lower weight-for-age Z-score was independently associated with postoperative enterocolitis, particularly with long aganglionic segments and delayed diagnosis [3].

3.5. Extraintestinal manifestations according to genetic basis

In syndromic forms, extraintestinal disease dominates prognosis: sensorineural deafness and pigmentary anomalies in Waardenburg–Shah syndrome, with peripheral neuropathy and leukodystrophy in SOX10 variants escaping nonsense-mediated decay; intellectual disability, epilepsy and cardiac malformations in Mowat–Wilson syndrome; hypoventilation, arrhythmias and neural crest tumours in congenital central hypoventilation syndrome; and predisposition to medullary thyroid carcinoma and phaeochromocytoma with exon 10 RET variants [2, 14, 24, 25, 27]. These entities are described in section 6.

4. Clinical Recognition and Warning Signs

ERNICA defines the classical triad as delayed meconium passage (more than 24 hours in a term neonate), abdominal distension and bilious vomiting, and recommends rectal biopsy whenever the history and clinical signs suggest the disease (level III evidence; strong recommendation) [3, 10]. An associated Hirschsprung syndrome or family history lowers the threshold for biopsy [3]. Biopsy should also be considered to exclude the disease in early-onset constipation with faltering growth, older children with persistent constipation or symptoms of a more generalised motility disorder, and patients with an absent rectoanal inhibitory reflex (RAIR) on manometry (conditional recommendation) [3].

Enterocolitis warning signs include explosive, foul-smelling or bloody diarrhoea and fever; explosive diarrhoea with poor peripheral perfusion, lethargy or dilated loops on radiography defines severe enterocolitis and requires admission [10]. ERNICA recommends suspecting enterocolitis with explosive, foul-smelling diarrhoea or a score above 4 on the Pastor and colleagues scale, with a low threshold for admission, particularly below one year of age [3].

For genetic assessment, OXF emphasises a three-generation pedigree addressing Hirschsprung disease, unexplained neonatal or infant deaths, deafness and pigmentary anomalies, neurological signs, thyroid carcinoma, phaeochromocytoma and parathyroid hyperplasia, together with determination of aganglionic segment length and confirmation of the diagnosis in the histology report [1]. Physical examination seeks pigmentary anomalies (white forelock, heterochromia, depigmented skin bands), dysmorphism and signs of trisomy 21, cardiac malformations and distal limb anomalies, because rare syndromes associate Hirschsprung disease with polydactyly, brachydactyly or hypoplasia of distal phalanges and nails [1]. Features suggesting syndromic disease include microcephaly, intellectual disability and uplifted earlobes (Mowat–Wilson); deafness and depigmentation (Waardenburg–Shah); sleep hypoventilation (congenital central hypoventilation); intrauterine growth restriction, microcephaly and distal limb anomalies (Smith–Lemli–Opitz); short stature, sparse hair and immunodeficiency (cartilage–hair hypoplasia); and hydrocephalus with adducted thumbs (L1 syndrome) [1, 2].

5. Diagnosis: Criteria, Tests and Algorithms

5.1. Histological diagnosis

Diagnosis requires representative rectal histology and must be confirmed before pull-through surgery (level III evidence; strong recommendation, unchanged in 2025) [3, 10]. Suction and surgical biopsies are equally accurate if they provide sufficient submucosa; the least invasive feasible method should be selected [3]. Samples should be taken from the posterior or lateral rectal wall, at least 2 cm above the dentate line or 3 cm from the anal verge, avoiding the physiological aganglionic or hypoganglionic zone of the distal rectum; 2–3 samples are advised for suction biopsy [3, 10]. The 2009 International Working Group recommends samples at least 3 mm in diameter, with one-third submucosa [10]. Any ganglion cells on haematoxylin and eosin (H&E) exclude the diagnosis; if none are seen, additional assessment is required. The 2025 version recommends combining H&E with calretinin immunohistochemistry for greater specificity, particularly in preterm infants, whose ganglion cells are small and immature [3]. In Hirschsprung disease, acetylcholinesterase activity is increased and calretinin is negative, except within 1–2 cm of the transition zone [3]. Acetylcholinesterase false negatives depend primarily on age, and an absent reaction does not exclude the diagnosis in very young neonates [10]. The retired GeneReviews chapter specified absence of submucosal ganglion cells in 50–75 sections as a criterion, with hypertrophic submucosal nerves as an ancillary finding [2]. In the European Paediatric Surgeons' Association survey (294 respondents from 61 countries), all performed rectal biopsy (61% suction, 39% surgical full-thickness), using H&E (77%), acetylcholinesterase (74%) and calretinin (31%) [29]. In Europe, uncertain cases can be discussed with an ERNICA centre through the already operational CPMS (Clinical Patient Management System) platform [3].

5.2. Complementary investigations

Anorectal manometry and contrast enema have lower sensitivity and specificity than an adequate biopsy, particularly in infants [10]. Preoperative contrast enema is recommended where possible to estimate aganglionosis level: a calibre change suggests the transition zone, but is less reliable proximal to the rectosigmoid junction and should raise the possibility of long-segment disease; it does not replace histology (conditional recommendation) [3, 10]. The most informative images are often obtained immediately after evacuation of the contrast [10]. Anorectal manometry documents absence of the rectoanal inhibitory reflex [3]. During surgery, precise mapping relies on frozen-section biopsies and, ideally, a circumferential (“doughnut”) biopsy at the transection level [10].

5.3. Genetic assessment

ERNICA recommends considering RET testing in nonsyndromic Hirschsprung disease (level II–III evidence; conditional recommendation), because it is the principal gene, permits more accurate recurrence-risk estimates and excludes the rare possibility of a MEN2A-associated variant. Genetic consultation should be offered to patients or parents wishing to undergo screening and to patients with a family history, in whom RET variants are more frequent [3, 10]. Since many RET variants are not inherited, trio testing (father, mother and child) is preferred [10]. Syndromic disease warrants genetic consultation and testing of the phenotype-associated gene [10]. The American Thyroid Association recommends counselling and RET genetic testing in infants or children with Hirschsprung disease and a germline exon 10 variant (grade B recommendation), and assessment for MEN2A in patients with Hirschsprung disease and exon 10 variants [14]. OXF suggests testing RET exons 10 and 11 when MEN2A or familial medullary carcinoma is present [1].

The utility of variant screening in isolated disease is limited by poor genotype–phenotype correlation, low sex-dependent penetrance, absence of hotspots and difficulties interpreting noncoding polymorphisms [1]. The retired GeneReviews chapter emphasised the absence of universally accepted guidelines and the interpretative difficulties caused by reduced penetrance; it proposed RET testing in nonsyndromic disease, potentially followed by EDN3 and EDNRB, and chromosomal microarray for multiple anomalies, growth impairment or developmental delay [2]. OXF recommends genomic analysis (microarray, panel or exome or genome sequencing) with signs of a syndrome or chromosomal abnormality, ZEB2 testing for microcephaly, intellectual disability and typical dysmorphism, and measurement of 7-dehydrocholesterol for intrauterine growth restriction, microcephaly or distal limb anomalies [1]. Tilghman and colleagues concluded that testing at least the RET regulatory network is justified for risk stratification, and that broader genomic analyses may be useful in clinical research [8].

5.4. Test limitations and report content

A negative panel result does not exclude a genetic contribution: exon sequencing alone does not detect intronic regulatory RET variants or, depending on the method, single- or multiexon deletions; microarray is required for deletions of 10q11.2, 13q22, 2q22 or 4p12 and large structural variants [2, 8]. In Mowat–Wilson syndrome, ZEB2 sequencing detects approximately 84% of pathogenic variants and deletion/duplication analysis approximately 15%; an epigenetic methylation signature may help classify variants of uncertain significance [25]. For congenital central hypoventilation syndrome, GeneReviews identifies single-gene PHOX2B testing as the molecular approach, staged according to the American Thoracic Society statement; exon 3 or whole-gene deletions escape sequencing, and parental assessment requires a test capable of detecting low-level somatic mosaicism [27]. The proportion of identifiable variants in a series is not equivalent to a test's clinical sensitivity in an individual patient, and a variant of uncertain significance cannot be reclassified as pathogenic on partial familial segregation, particularly in a disease with incomplete penetrance [25, 27].

Reports should state the gene, versioned transcript (for example, NM_020975.6 for RET), DNA and protein HGVS nomenclature, zygosity, ACMG/AMP classification and technical limitations, including noncoding-region coverage and detection of copy-number variants and mosaicism [9, 25]. For RET exon 10 variants (for example, NM_020975.6:c.1858T>C, p.(Cys620Arg), validated using VariantValidator), reports should explicitly state the MEN2A implications and ATA risk category [9, 14, 30].

5.5. Practical algorithm

6. Differential Diagnosis

6.1. Other causes of intestinal obstruction and severe constipation

In the newborn with intestinal obstruction, the differential diagnosis includes gastrointestinal malformations (atresia, malrotation, duplication), meconium ileus of cystic fibrosis, conditions causing ganglioneuromatosis such as MEN2B, and disorders of the enteric nervous system or musculature grouped as chronic intestinal pseudo-obstruction, including intestinal neuronal dysplasia and ACTG2-related disorders [2]. Acquired forms of severe constipation or obstruction may result from maternal factors such as infection or alcohol ingestion, or from congenital hypothyroidism [2]. Intestinal neuronal dysplasia type B may be clinically indistinguishable, although it tends to present later (between 6 months and 6 years), with hyperplasia of the enteric ganglia and «giant ganglia», a controversial criterion; it may coexist proximal to the aganglionic segment in about 20% of patients with Hirschsprung disease [2]. A rectal biopsy showing ganglion cells excludes Hirschsprung disease [2, 3].

6.2. Syndromic and chromosomal forms

The retired GeneReviews chapter estimated a chromosomal abnormality in approximately 12% of patients and at least one other congenital anomaly in approximately 18% [2]. Trisomy 21 is the most frequent chromosomal abnormality: it occurs in 2–10% of patients with Hirschsprung disease, while 0.6–3% of people with Down syndrome have the disease [2]. In Badner's series, trisomy 21 was more frequent among affected individuals but not their unaffected siblings, without an association with maternal age [7]. OXF includes Hirschsprung disease among the most frequent malformations in Down syndrome, and Smith lists it among the syndrome's occasional gastrointestinal anomalies, which collectively occur in 12% [31, 32]. Deletions encompassing disease genes (del13q22 with EDNRB, del10q11.2 with RET, del10q23.1 with NRG3, del2q22 with ZEB2 and del4p12 with PHOX2B) helped identify these genes and support haploinsufficiency [2].

The Smith appendix lists aganglionosis as frequent in Down, Mowat–Wilson, Smith–Lemli–Opitz and Waardenburg syndromes, and as occasional in Aarskog, cat eye, 13q deletion, Fryns, Jeune asphyxiating thoracic dystrophy, cartilage–hair hypoplasia, Nager, Okihiro, Pitt–Hopkins, Rubinstein–Taybi, Senter-KID and Toriello–Carey syndromes, among others [41]. In Werner-type mesomelic dysplasia (MIM 188740; AD, due to point variants or duplication of the ZRS regulatory sequence of SHH, in intron 5 of LMBR1), the bone dysplasia atlas reports a rare association with cryptorchidism, congenital heart disease and Hirschsprung disease [42]. In the X-linked hydrocephalus spectrum (L1CAM), Hirschsprung disease is listed among the occasional anomalies [40].

6.3. Waardenburg–Shah syndrome in detail

Waardenburg syndrome results from absence of functional melanocytes in the skin, hair, eyes and cochlear stria vascularis [34]. Waardenburg described it in 1951, identifying it in 1.4% of children with congenital deafness and estimating an incidence of 1 in 42,000 in the Netherlands [33]. Types 1 and 3 are caused by PAX3; type 2 by MITF (15%), SOX10 (15%), EDNRB and EDN3 (a small percentage), SNAI2 or KITLG; type 4 combines type 2 features with Hirschsprung disease, with deafness in 84% [33]. In type 4, SOX10 accounts for 50% of cases and EDN3/EDNRB for 20–30%, with inheritance neither fully recessive nor fully dominant; rarely, homozygous MITF variants produce the phenotype, with both parents having mild type 2 disease [33]. Carriers of MITF variants have minimal or no risk of Hirschsprung disease [34]. People with SOX10 variants frequently have inner-ear malformations (hypoplastic or absent semicircular canals, enlarged vestibules, cochlear anomalies), absent olfactory bulbs and white-matter abnormalities; some develop demyelinating peripheral neuropathy or progressive central involvement [1, 33]. SOX10 variants are also identified in approximately one-third of patients with Kallmann syndrome and deafness [5]. The Brazilian SGRT manual presents clinical criteria (two major criteria, or one major and two minor), states that syndrome-related morbidity and mortality are predominantly attributable to type 4 because of fatal enterocolitis risk, and recommends cochlear implantation for deafness [43]. Orphanet places Waardenburg–Shah syndrome (ORPHA:897) in the prevalence class below 1 per 1,000,000 [5].

6.4. Mowat–Wilson syndrome in detail

Initially described in six patients with characteristic facies, intellectual disability and microcephaly, five with Hirschsprung disease, Mowat–Wilson syndrome was subsequently recognised without aganglionosis [26]. Hirschsprung disease frequency varies across sources: 44% with biopsy-confirmed disease in current GeneReviews (Ivanovski and colleagues' 2018 series of 87 patients), 30.6% in Smith, 67% in OXF (Zweier's 2003 series) and 41–71% in retired GeneReviews; the current GeneReviews estimate, revised in June 2026, is adopted here [2, 25, 26, 44]. The sex ratio is approximately equal (183:161), although older reports suggested male predominance [25]. Surgical outcomes are worse than in nonsyndromic disease, with prolonged parenteral nutrition and recurrent enterocolitis, possibly attributable to a generalised motility disorder [25]. Prevalence has been estimated at 1 in 50,000 to 70,000 live births [25]. The syndrome should be considered in patients with suspected but unconfirmed Angelman syndrome, given the broad-based gait, flexed arms, smiling and absent speech [26]. Its own differential includes CHARGE syndrome (without Hirschsprung disease), Rubinstein–Taybi, Smith–Lemli–Opitz, Goldberg–Shprintzen and Pitt–Hopkins syndromes [25].

6.5. Congenital central hypoventilation syndrome in detail

In the series cited by retired GeneReviews, approximately 20% of patients with congenital central hypoventilation had Hirschsprung disease, a combination termed Haddad syndrome, now little used [2, 27]. Almost all carry a heterozygous PHOX2B variant [1]. The risk of Hirschsprung disease and neural crest tumours depends on genotype: neuroblastoma was not observed with polyalanine genotypes 20/24 to 20/26 and generally not with 20/27, although an infant with genotype 20/33 developed metastatic neuroblastoma. Overall, neural crest tumours occur in fewer than 5% of carriers of genotypes 20/30 to 20/33 and approximately 50% of nonpolyalanine variant carriers, in whom ganglioneuroblastoma and ganglioneuroma each affect fewer than 5% [27]. OXF recommends clinical and radiological neuroblastoma surveillance whenever the variant is not a polyalanine expansion [1]. Severe constipation without Hirschsprung disease is characteristic, and oesophageal dysmotility in the first year tends to improve [27]. The incidence of congenital central hypoventilation has been estimated at 1 in 200,000 live births in France and 1 in 148,000 in Japan, with probable underdiagnosis [27].

6.6. Relationship with MEN2: when to suspect it

Familial coexistence of Hirschsprung disease and medullary thyroid carcinoma, phaeochromocytoma or hyperparathyroidism should prompt analysis of RET exons 10 and 11 [1]. Both MEN2A and familial medullary carcinoma may be associated with Hirschsprung disease in some families [1]. Hirschsprung disease almost always presents shortly after birth, but it should be excluded in adults with MEN2A and exon 10 variants who have suggestive colonic symptoms [14]. Surveillance, the timing of prophylactic thyroidectomy and the treatment of MEN2 follow the ATA recommendations.

7. Treatments and Risk Management Strategies

7.1. Principles and organisation of care

Hirschsprung disease is treated surgically by resection of the aganglionic bowel [1]. ERNICA recommends performing pull-through surgery in centres with at least two paediatric colorectal surgeons, pathology, radiology and anaesthetic expertise, paediatric and neonatal intensive care, and continuous specialist nursing. Centres should manage the entire care pathway, including complications, all disease extents and follow-up into adulthood, and participate in prospective registries and continuous improvement (level III evidence; strong recommendations, unchanged in 2025) [3, 10]. Patients should receive information about patient organisations and existing guidelines as early as possible [3]. Implementation of the 2025 update will be monitored through the EPSA|ERNICA registry (European Pediatric Surgical Audit), with the next formal revision planned for 2030 [3].

7.2. Preoperative care

While awaiting biopsy results and until definitive surgery, rectal irrigations with normal saline are recommended 1–3 times daily; parents can be taught to perform them at home (strong recommendation) [3, 10]. Irrigations effectively decompress the bowel in approximately 75% of patients; failure often suggests long-segment disease [10]. In the United Kingdom and Ireland cohort, initial decompression used irrigations in 86.2% and a stoma in 12.8%; 27.4% of those initially managed with irrigations subsequently required a stoma, resulting in 36.4% of infants having a stoma [6]. A stoma is indicated when irrigations fail to decompress the bowel, enterocolitis fails to respond to nonsurgical treatment, or perforation occurs; ileostomy is the safest empirical level, and a circumferential biopsy at the stoma site establishes ganglion status at that level [3]. At induction for pull-through surgery, a single intravenous broad-spectrum antibiotic dose covering aerobes and anaerobes is recommended according to local protocols and resistance patterns; treatment may continue for 24–48 hours postoperatively (level II–III evidence; strong recommendation) [3, 10].

The 2025 update introduced two new recommendations. The first suggests screening all patients for congenital anomalies of the kidney and urinary tract by ultrasound within the first year (level II evidence; conditional recommendation), with urological referral for abnormalities [3]. The second recommends preoperative malnutrition screening, using growth as the principal indicator, maintaining standard feeding recommendations (including breastfeeding and standard formula), and providing targeted nutritional support if growth deviates, for example with a weight-for-age Z-score of −2 or below (level II evidence; strong recommendation) [3]. Extensively hydrolysed formulas were discussed, but the evidence was considered insufficient to recommend them [3]. The panel also highlighted the need to investigate cardiovascular screening, given cardiac comorbidity of 6–10% [3].

7.3. Pull-through surgery

The most frequently performed operations are transanal endorectal pull-through, including its laparoscopically assisted variant, and the Duhamel procedure. No evidence establishes overall superiority of either technique in complications or long-term bowel function; each centre should therefore use the technique with which it has greatest experience (level III evidence; conditional recommendation) [3]. Surgery is usually elective, 2–3 months after diagnosis, when the patient is stable, growing and has decompressed bowel; no specific advantages of neonatal surgery have been identified [3]. The anal canal should be preserved because the transitional mucosa above the dentate line contains nerve endings responsible for sensation and the continence sampling reflex. The 2025 update refined this recommendation: transanal dissection should begin 0.5–2 cm above the dentate line, remaining above the anorectal line (proximal end of the anal columns), and the anastomosis should be constructed above that line (approved by 74% of voters) [3]. In endorectal pull-through, no muscular cuff (Swenson) and a short cuff (less than 2–3 cm) have comparable outcomes; long seromuscular cuffs should be avoided because of their association with obstruction, constipation and enterocolitis [3, 10]. The colon should be transected at least 5–10 cm proximal to the first normal biopsy, with mapping biopsies if the level is uncertain, circumferential biopsy at transection and submission of the complete, oriented specimen to the pathologist (strong recommendation) [3]. Patients with extensive intestinal aganglionosis and irreversible intestinal failure may be candidates for intestinal transplantation [2].

7.4. Postoperative care

Specialist paediatric and nursing care, enhanced recovery after surgery (ERAS) principles, parental counselling and active prevention of perianal dermatitis are recommended; dermatitis is particularly common after a previous stoma, extensive disease or neonatal surgery [3, 10]. Enteral feeding can begin 24–48 hours after surgery in most cases [3]. In 2020, ERNICA recommended calibration of the coloanal anastomosis 2–3 weeks postoperatively with a size 12 Hegar dilator from term to 6 months of age [10]; in 2025, this recommendation changed: calibration should detect strictures, preferably performed by a surgeon in a paediatric centre, with neither a mandatory schedule nor calibre, guided by clinical findings (conditional recommendation) [3]. The update strongly recommends against preventive serial dilatations, which do not prevent stricture, enterocolitis or constipation and may be painful and traumatic; dilatation remains a treatment for diagnosed strictures, with a low threshold for general anaesthesia [3].

7.5. Hirschsprung-associated enterocolitis

Table sources: [3, 10, 13]. None of the consulted guidelines gives doses for metronidazole or intravenous antibiotics; consequently, none are presented here, and paediatric formularies and local protocols should be followed. Contrast enema should not be performed during an acute episode because of perforation risk [10, 13]. Patients with Hirschsprung disease have an approximately fivefold greater risk of inflammatory bowel disease than the general population; persistently elevated faecal calprotectin should prompt consideration of endoscopy [10]. Differences between the guidelines regarding probiotics reflect conflicting evidence: of two randomised trials available in 2020, one showed no risk reduction and the other reduced incidence; a meta-analysis including three additional studies did not demonstrate prevention [10].

7.6. Intrasphincteric botulinum toxin

Intrasphincteric botulinum toxin injections are recommended for recurrent or persistent outlet obstruction symptoms and/or enterocolitis (level III evidence; conditional recommendation) [3]. In the cited studies, 62–89% improved after the first injection, reducing admissions for obstructive symptoms; injections may require repetition every 3–6 months, under brief general anaesthesia, into four quadrants at the dentate line, exposed using retractors or under ultrasound guidance [3, 10]. The 2025 update reports symptomatic relief in approximately 66–71%, adverse effects in approximately 17% (transient faecal incontinence, anal pain, muscle fatigue), and no clear dose–response relationship, preventing recommendation of a standardised dose [3]. This use is off-label: the US BOTOX® label (onabotulinumtoxinA, Allergan, BLA 103000) contains no gastrointestinal or anal indications and has a boxed warning concerning distant spread of toxin effects (asthenia, generalised weakness, diplopia, ptosis, dysphagia, dysphonia, dysarthria, urinary incontinence and breathing difficulties, potentially fatal, with the greatest probable risk in children treated for spasticity) [45]. In the European Union, the consulted EMA centrally authorised medicines list contains no botulinum toxin indication for this use [12].

7.7. Poor functional outcomes and transition

Children with normal intellectual development who have not achieved faecal continence by 4 years should undergo assessment of stool patterns and diet, examination under anaesthesia ± manometry (integrity of the anal canal, sphincters and dentate line; rolled muscular cuff, stricture or rectal spur), contrast enema and, if necessary, endorectal ultrasound (strong recommendation) [3]. With an intact anal canal, first-line treatment is medical: oral laxatives ± enemas for hypomotility with a dilated colon; a constipating diet ± loperamide ± bulking agents (pectin, psyllium) for hypermotility, with faecal calprotectin, possible ileocolonoscopy and repeat biopsy [3]. With anal canal injury, a bowel management programme is recommended (retrograde enemas, antegrade irrigation through an appendicostomy or caecostomy), reserving enterostomy as a last resort [3]. Persistent obstructive symptoms require exclusion of mechanical causes, review of original specimen margins, repeat biopsy, a trial of botulinum toxin and consideration of reoperation for refractory stricture, twisted pull-through, rolled cuff (Soave), spur (Duhamel) or transition-zone pull-through; reoperation may carry relatively high incontinence rates [3, 10]. Rectal-probe biofeedback is not routinely recommended, while pelvic floor physiotherapy is a promising noninvasive alternative (one study reduced incontinence from 81.1% to 40.5%) [3].

7.8. Syndromic forms and genetic risk management

In syndromic forms, the treatment of Hirschsprung disease is standard, but comorbidities determine risk. In Mowat–Wilson syndrome, surgical outcomes are poorer, with prolonged parenteral nutrition and recurrent enterocolitis [25]. In cartilage–hair hypoplasia, postoperative mortality may reach 38%, mainly from enterocolitis-associated sepsis [37]. In congenital central hypoventilation, sedatives, anaesthetics and other respiratory depressant drugs should be avoided, and Hirschsprung disease should be assessed (suction biopsy in the neonatal period or full-thickness biopsy later) according to symptoms and genotype, with chest and abdominal imaging and urinary catecholamines for neural crest tumours in at-risk genotypes [27]. When a RET exon 10 cysteine variant is identified, management comes to include surveillance and prophylactic thyroidectomy guided by the ATA risk category (moderate risk for codons 609, 611, 618 and 620) [14, 22].

7.9. Regulatory status

Table sources: [3, 11–13, 45].

7.10. Clinical trials and developments in the past 6–12 months

Both published trials have limitations precluding immediate generalisation. The nutritional trial was open-label, conducted in a Chinese population, with an early outcome (3 months) and an enterocolitis definition whose instrument is not specified in the consulted abstract. The absolute reduction is substantial but its confidence interval wide; the ERNICA 2025 recommendation, preceding publication, already recommended malnutrition screening and targeted support only when growth deviates [3, 46]. The surgical trial was single-centre, with a 1.1-point Rintala score difference and no overall quality-of-life difference. The authors themselves consider this consistent with individualised technique selection, aligning with ERNICA's recommendation to use the technique with which the centre has greatest experience [3, 47]. Neither trial assessed genetic subgroups, and they should not be compared indirectly.

In research, the 2025 multiancestry genome-wide association study identified JAG1, HAND2, ZNF25 and UNC5C loci and proposed a polygenic risk score applicable across ancestries, without prospective clinical validation to date [28]. In October 2025, the European Commission granted orphan designation to GDNF combined with sodium butyrate, while the French phase 3 butyrate enema trial was updated in September 2026 with a planned November 2026 start [11, 48]. These represent genetic research, a regulatory designation and a registered trial without participants, respectively, rather than authorised therapies. The ERNICA 2025 update was published in July 2026, with corrections in May and June 2026 [3].

8. Reproductive Options and Family Counselling

8.1. Preliminary step: exclude a syndromic or Mendelian form

Counselling begins by establishing that disease is nonsyndromic and no discernible Mendelian pattern exists in the family; assessment then addresses the proband's aganglionic segment length and sex, the sex of the expected child (when known), and the pedigree [1]. If the proband has a chromosomal anomaly, an associated syndrome or a pathogenic RET, EDN3 or EDNRB variant, counselling follows that condition [2]. Without an identified cause, the disease is considered polygenic, with reduced penetrance, variable expressivity and 4:1 male predominance [2]. This is a classical example of the proband's sex altering risk to relatives [49].

8.2. Empirical risks in isolated disease

In sporadic cases without RET testing, overall sibling recurrence risk is 4%, against a population incidence of 0.02% [1, 7]. Risk is higher for siblings of probands with long-segment disease and depends on both proband and sibling sex; short-segment disease carries lower risk and is more consistent with a recessive or multifactorial model [2]. The following table reproduces Badner and colleagues' empirical risks as presented in OXF (Table 3.20, checked against the original PDF) and retired GeneReviews (Table 5) [1, 2, 7].

Risks are higher when the proband belongs to the less affected sex (female) and disease is extensive, consistent with a sex-dependent multifactorial threshold [1, 7]. Smith's recurrence-risk table for multifactorial defects gives a 3–5% risk for future children of unaffected parents who have an affected child with “Hirschsprung anomaly” [50]. Tilghman and colleagues cite sibling recurrence risks of 3% to 17%, varying with sex, extent and familial occurrence [8]. With multiple affected relatives, counselling should communicate higher risk and low penetrance [1]. Children of a proband with nonsyndromic disease of unknown cause have increased risk, but precise estimates are unavailable [2].

8.3. When a variant has been identified

In families with a RET variant, penetrance is 50–72% in carriers and depends mainly on the sex of the carrier, being variable and family-specific [1]. Each child of a carrier has a 50% probability of inheriting the variant but may not manifest the disease, and severity is not predictable [2]. A relevant proportion of affected individuals inherited the variant from an unaffected parent; in some documented cases, the patient inherited two variants in different genes, one from each parent, suggesting digenic inheritance [2]. The proportion of cases due to a de novo variant is unknown, and parental evaluation should include physical examination, a history of intestinal obstruction in childhood or chronic constipation, and molecular testing [2]. Tilghman and colleagues estimated, for a person without identifiable risk factors, a population risk of 5.33 per 100,000 live births (about 1 in 18,800); for those with both an enhancer risk genotype and a rare coding variant, 2.85 per 1,000 (about 1 in 350); and for carriers of copy number variants, 8.38 per 1,000 (about 1 in 120) [8]. These values derive from a population of European ancestry and assume an incidence of 15 per 100,000; even in the highest-risk group, the absolute risk remains low, which limits individual predictive value [8]. For dosage-sensitive EDNRB variants, the Mennonite example (74% in homozygotes and 21% in heterozygotes for NM_001122659.3:c.828G>T p.(Trp276Cys)) shows the magnitude of the variation [18].

When the variant lies in RET exon 10, counselling changes in nature, because carriers, including relatives without Hirschsprung disease, are at risk of medullary thyroid carcinoma and phaeochromocytoma; the ATA recommends offering counselling and testing to these patients, and predictive testing in relatives follows MEN2 rules [14].

8.4. Syndromic forms

In Mowat–Wilson syndrome, almost all cases arise de novo; sibling risk is low (approximately 2%, or up to 2.3% according to Smith, based on 4 sibling pairs in 175 families) because of parental gonadal or combined somatic and gonadal mosaicism, and affected individuals have no known offspring [25, 26]. SOX10 variants in Waardenburg–Shah syndrome are dominantly inherited; biallelic EDNRB/EDN3 forms approach autosomal recessive sibling risk, although heterozygotes may have isolated Hirschsprung disease [2, 33]. In congenital central hypoventilation, most PHOX2B variants are de novo, mosaicism occurs in 5–25% of asymptomatic parents, and the fetus should be considered at risk even when the variant is not detected in either parent [27].

8.5. Prenatal and preimplantation diagnosis

Prenatal diagnosis of Hirschsprung disease itself is not possible; fetal bowel dilatation has been reported only exceptionally in total colonic aganglionosis, and most affected fetuses have no ultrasound abnormalities [1, 10]. When the familial variant is known, prenatal or preimplantation testing is technically possible, but may not be desired because of incomplete penetrance, variable expressivity and curative surgical treatment; requests are uncommon, and differences in perspective between professionals and families should be discussed [1, 2]. For syndromic forms with an identified alteration (for example, Mowat–Wilson or a balanced parental chromosomal rearrangement), prenatal and preimplantation testing is offered according to mosaicism or rearrangement risk [25]. Proband DNA banking is recommended when the cause is unidentified, anticipating advances in methods [2, 25].

8.6. Fertility and reproduction in adult patients

The ERNICA 2025 update recommends informing female patients that the condition may affect fertility (level II–III evidence; strong recommendation): in large cohorts, women had lower fertility rates than controls, were older at first childbirth and more often had only one child, even after adjustment for education and associated malformations. Men had no significant reduction, although isolated subfertility cases have been described [3]. Sexual function should also be addressed during follow-up, with multidisciplinary referral (gynaecology, reproductive medicine, pelvic floor physiotherapy); up to 50% of sexually active women report pain during intercourse [3]. Fertility discussions should begin in adolescence or early adulthood to support informed family planning [3].

9. Special Considerations: Population Diversity and Epidemiology

Approximately 1 in 5,000 live births is the most frequently cited estimate [1, 10]. Retired GeneReviews, citing Torfs (1998), reported 1.5 per 10,000 live births in people of northern European origin, 2.1 in African Americans and 2.8 in Asians [2]. In contrast, OXF describes high prevalence in Asians, intermediate prevalence in Caucasians and lowest prevalence in African Americans, differing from retired GeneReviews regarding African Americans; the consulted sources do not resolve this discrepancy [1, 2]. According to Orphanet, birth prevalence is 15 per 100,000 worldwide, with 13.2 in Europe, 21 in the United States and 22 in Taiwan [4, 5]. The ERNICA 2025 update, based on the EUROCAT European congenital anomaly registry network (2012–2018 live births), reports 1.43 per 10,000 live births (95% CI 1.37–1.50) [3]. In the United Kingdom and Ireland, the 2010–2012 population cohort estimated 1.8 per 10,000 (95% CI 1.5–1.9), with 81% of infants initially presenting to hospitals without tertiary paediatric surgery, requiring transfer [6]. These figures concern live births and population-based or registry series and cannot be extrapolated to countries lacking their own data; no Portugal- or Brazil-specific data were found in the consulted sources.

Among founder populations, the Pennsylvania Mennonite population carries a founder EDNRB variant (NM_001122659.3:c.828G>T p.(Trp276Cys)) responsible for a significant proportion of cases [2, 18]. Cartilage–hair hypoplasia, with Hirschsprung disease in 7–9% of affected individuals, is prevalent in the Old Order Amish and Finnish populations [2], and familial dysautonomia, also associated, affects 1 in 3,700 live births in the Ashkenazi Jewish population [2]. The rs2435357 T risk allele is more frequent in controls of Chinese ancestry (47%) than of European ancestry (20–30%), and population variation in total polygenic risk from RET, SEMA3 and NRG1 has been demonstrated in European families [20, 23]; benign NRG1 variants together with RET variants increase susceptibility mainly in the Chinese population [2]. The 2025 multi-ancestry polygenic score performed comparably to ancestry-specific models [28].

Male predominance decreases with disease extent: 4.5:1 in short-segment and 1.75:1 in long-segment disease, with equal numbers of boys and girls in long-segment disease according to retired GeneReviews [1, 2]. Trisomy 21 is overrepresented (2–10% of patients with Hirschsprung disease) [2]. Regarding gestational age, preterm infants have increased in proportion in more recent series (from 5% to 14%) and require particular attention to histology because of ganglion cell immaturity [3, 10]. No environmental causes are known [8].

10. Illustrative Clinical Case

10.1. Family with Hirschsprung disease and RET p.(Cys620Arg)

In 2025, Tanaka and colleagues published the case of a Japanese family with familial Hirschsprung disease and a germline RET exon 10 variant [30]. The proband, a 33-year-old man, had been diagnosed with total colonic aganglionosis at one month of age because of intestinal obstruction and operated on at one year (modified Boley procedure); he had episodes of residual intestinal inflammation in the following year, resolved with antimicrobials, and follow-up ended 14 years after surgery [30]. The family was re-evaluated when a son of the proband was born with frequent bilious vomiting, abdominal distension and poor feeding from the first day; this infant was operated on at 8 months (laparoscopic Duhamel) and histology showed long-segment aganglionosis [30]. After genetic counselling, the heterozygous variant NM_020975.6:c.1858T>C, p.(Cys620Arg) (rs77316810), absent from gnomAD and classified as pathogenic by ACMG/AMP criteria (PS1, PM1, PM2, PP3, PP5), was identified in the proband and his son [9, 30]. Family testing showed that the variant had been transmitted by the proband's mother, who had no relevant medical history, and that it was also present in a 2-year-old daughter without Hirschsprung disease, whereas the father and the elder brother were negative; several of the mother's siblings had died in early childhood of unknown causes (pedigree in Figure 1 of the article: https://pmc.ncbi.nlm.nih.gov/articles/PMC12253982/figure/FIG1/) [30].

Because the variant belongs to the ATA moderate-risk category for medullary thyroid carcinoma, surveillance was proposed. The proband's neck ultrasound was normal (Figure 2: https://pmc.ncbi.nlm.nih.gov/articles/PMC12253982/figure/FIG2/), and carcinoembryonic antigen (3.17 ng/mL), calcitonin (6.96 pg/mL) and parathyroid hormone were within reference ranges; ultrasound and markers were subsequently repeated every six months [30]. His mother, without thyroid abnormalities, had elevated plasma free metanephrines (192 pg/mL according to the text; article table 5 gives 263 pg/mL for free metanephrine) and elevated levels of all three catecholamine fractions. MRI showed a right adrenal mass with intense uptake on ¹³¹I-MIBG scintigraphy, consistent with phaeochromocytoma, and a small left-sided nodule (Figure 3: https://pmc.ncbi.nlm.nih.gov/articles/PMC12253982/figure/FIG3/) [30]. The proband's MRI revealed a 14-mm left adrenal nodule, not suggestive of an adenoma, undergoing investigation (Figure 4: https://pmc.ncbi.nlm.nih.gov/articles/PMC12253982/figure/FIG4/) [30]. The authors were considering testing the children of a deceased twin brother whose monozygosity had not been confirmed; one of these children had chronic constipation [30].

10.2. Teaching points

The case illustrates four aspects: the incomplete penetrance of Hirschsprung disease in RET variant carriers (carrier mother and daughter without the disease); the possibility of the same cysteine variant having a loss-of-function effect in the intestine and a gain-of-function effect in neuroendocrine tissue; the value of genetic testing in the proband with familial Hirschsprung disease, as recommended by ERNICA and the ATA; and the fact that MEN2A manifestations may arise in relatives without intestinal disease [10, 14, 30]. The authors stress the lack of consensus on whether phaeochromocytoma surveillance should be applied to families with Hirschsprung disease and a RET variant without medullary carcinoma; however, the ATA treats variants at codons 609, 611, 618 and 620 as moderate-risk MEN2A variants, and the management of these carriers should follow the MEN2 recommendations, and not only the practices of the report [14, 22, 30]. The discrepancy between the metanephrine value given in the text and in the table of the published report is a limitation of the report itself.

11. Prognosis and Long-Term Follow-up

11.1. Course after surgery

Surgery is anatomically curative, but postoperative bowel dysfunction is frequent [10]. OXF gives chronic constipation and incontinence (soiling) in 10–15% as long-term complications [1]. Tilghman and colleagues report persistent bowel dysfunction and enterocolitis in 30–50% [8]. The tendency to enterocolitis diminishes with time, with most episodes in the first years after pull-through [10]. In experienced centres, reoperation rates are low and long-term continence in rectosigmoid disease is mostly good to normal [10]. Children with an associated syndrome and cognitive impairment often achieve continence later [10]. Inflammatory bowel disease is approximately five times more frequent than in the general population [10]. Hirschsprung disease has a poor prognosis in cartilage–hair hypoplasia, with postoperative mortality up to 38% [37]; in Waardenburg syndrome, morbidity and mortality concentrate in type 4 because of enterocolitis risk [43].

11.2. Follow-up programme

The difference in ages for beginning transition preparation (13–14 years in 2020; 10–12 years in the discussion of the 2025 update) reflects evolving recommendations; the 2025 version is adopted [3, 10].

11.3. Reference networks and patient associations

The relevant European Reference Network is ERNICA, which includes Hirschsprung disease among its conditions, provides CPMS for cross-border case discussion and implements recommendations through the EPSA|ERNICA registry [3, 10]. Patient associations participating in guideline development included SoMA (Germany, anorectal malformations and Hirschsprung disease), A.Mor.Hi (Associazione Italiana Morbo di Hirschsprung) and the Dutch Hirschsprung disease association [3]. OXF and retired GeneReviews list the Hirschsprung's & Motility Disorders Support Network (United Kingdom, www.hirschsprungs.info); retired GeneReviews also lists the International Foundation for Functional Gastrointestinal Disorders and Pull-thru Network (United States), with contact details dating from 2015 [1, 2]. No specific Portuguese or Brazilian associations were identified in the consulted sources.

12. Summary and Final Considerations

Hirschsprung disease is a neurocristopathy in which incomplete intestinal colonisation by vagal neural crest cells leaves the rectum and a contiguous, variably extensive segment without ganglia. Frequency is approximately 1 in 5,000 live births, with male predominance diminishing as extent increases [1, 3]. Approximately 70% of cases are isolated, 20% syndromic or associated with another anomaly, and 10% chromosomal, predominantly trisomy 21 [1]. Isolated disease exemplifies oligogenic inheritance: RET is the principal locus, with rare coding variants and a common intronic enhancer variant (rs2435357, NM_020975.6:c.73+9277T>C) that, together with other regulatory alleles, genes in RET, endothelin and semaphorin pathways, and structural variants, accounts for an identifiable genetic factor in approximately 72% of patients [8, 9, 20]. Syndromic forms — Waardenburg–Shah (SOX10, EDNRB, EDN3), Mowat–Wilson (ZEB2), congenital central hypoventilation (PHOX2B), Goldberg–Shprintzen (KIFBP), cartilage–hair hypoplasia and others — require active clinical recognition because they alter prognosis, surveillance and counselling [2, 25, 27]. The allelic relationship with MEN2A involving RET exon 10 cysteine variants justifies genetic testing and endocrine assessment when such variants are identified [10, 14].

Diagnosis requires representative rectal biopsy with H&E and calretinin before any definitive surgery; treatment is surgical pull-through in an experienced centre, without demonstrated superiority among techniques [3]. The ERNICA 2025 update added renal and nutritional screening, elimination of preventive dilatations, rejection of botulinum toxin for enterocolitis prevention, and explicit attention to diet, fertility, sexuality and transition [3]. No medicine is authorised for the disease; botulinum toxin is used off-label without a standard dose, while recent developments comprise surgical and nutritional trials, a European orphan designation and association genetics [11, 12, 28, 46, 47]. For counselling, Badner's empirical sibling risks of 1% to 33%, depending on sex and extent, remain the basis for isolated disease without an identified variant, and prenatal diagnosis of the disease itself is not possible [1, 7].

13. Bibliographic References

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