Genetic basis of Hirschsprung's disease

Hirschsprung disease

Hirschsprung disease (HSCR) is a rare congenital intestinal disease that occurs in 1 in 5,000 live births. HSCR is characterized by the absence of ganglion cells in the myenteric and submucosal plexuses of the intestine. Most patients present during the neonatal period with the first meconium passage delayed beyond 24 h, abdominal distension and vomiting. Syndromes associated with HSCR include trisomy 21, Mowat-Wilson syndrome, congenital central hypoventilation syndrome, Shah-Waardenburg syndrome and cartilage-hair hypoplasia. Multiple putative genes are involved in familial and isolated HSCR, of which the most common are the RET proto-oncogene and EDNRB. Diagnosis consists of visualization of a transition zone on contrast enema and confirmation via rectal biopsy. HSCR is typically managed by surgical removal of the aganglionic bowel and reconstruction of the intestinal tract by connecting the normally innervated bowel down to the anus while preserving normal sphincter function. Several procedures, namely Swenson, Soave and Duhamel procedures, can be undertaken and may include a laparoscopically assisted approach. Short-term and long-term comorbidities include persistent obstructive symptoms, enterocolitis and soiling. Continued research and innovation to better understand disease mechanisms holds promise for developing novel techniques for diagnosis and therapy, and improving outcomes in patients.

Sexual function and lower urinary tract symptoms after minimally invasive endorectal pull-through in adolescent males with Hirschsprung disease

BACKGROUND

Effects of colorectal resection on sexual function and the lower urinary tract are inadequately studied in patients with Hirschsprung disease (HD). This study aimed to increase existing knowledge on sexual function and lower urinary tract symptoms (LUTS) in HD male adolescents operated with minimally invasive endorectal pull-through (ERPT).

METHODS

Non-syndromic male adolescents (12-18 years) operated with ERPT were invited to participate in this single-center cross-sectional study which included a semi-structured interview on sexual function and LUTS, a questionnaire recording LUTS, and a urodynamic study. Uroflowmetry curves were eligible for evaluation if the voided volume was >50% of expected bladder capacity. Ethical approval and informed consent were obtained.

RESULTS

Of 37 eligible male adolescents, 35 (95%) with a median age of 14.9 (12.0 -18.3) years were included. 94% had rectosigmoid aganglionosis, and 97% underwent a minimally invasive ERPT. 34 (97%) visited the outpatient clinic. The ability to get erections and to ejaculate was assessed in 25/35 (71%) adolescents. 25/25 (100%) could get an erection, and of adolescents ≥15 years 14/15 (93%) could ejaculate. 32 (91%) returned the questionnaire and underwent urodynamic studies. 15/32 (47%) reported LUTS, but most had only sporadic LUTS. 31/32 (97%) were highly satisfied with their bladder function. Sporadic urinary incontinence was reported by 4/32 (13%), but none reported social problems due to this. Of the eligible 28/32 (88%) uroflowmetry curves, 15/28 (54%) were normal.

CONCLUSIONS

Minimally invasive ERPT seems to preserve sexual function and does not induce lower urinary tract symptoms in adolescent HD males.

LEVEL OF EVIDENCE

III.

A New Transgenic Tool to Study the Ret Signaling Pathway in the Enteric Nervous System

The receptor tyrosine kinase Ret plays a critical role in regulating enteric nervous system (ENS) development. Ret is important for proliferation, migration, and survival of enteric progenitor cells (EPCs). Ret also promotes neuronal fate, but its role during neuronal differentiation and in the adult ENS is less well understood. Inactivating RET mutations are associated with ENS diseases, e.g., Hirschsprung Disease, in which distal bowel lacks ENS cells. Zebrafish is an established model system for studying ENS development and modeling human ENS diseases. One advantage of the zebrafish model system is that their embryos are transparent, allowing visualization of developmental phenotypes in live animals. However, we lack tools to monitor Ret expression in live zebrafish. Here, we developed a new BAC transgenic line that expresses GFP under the ret promoter. We find that EPCs and the majority of ENS neurons express ret:GFP during ENS development. In the adult ENS, GFP+ neurons are equally present in females and males. In homozygous mutants of ret and sox10-another important ENS developmental regulator gene-GFP+ ENS cells are absent. In summary, we characterize a ret:GFP transgenic line as a new tool to visualize and study the Ret signaling pathway from early development through adulthood.

Embryology and anatomy of Hirschsprung disease

Bowel has its own elegant nervous system - the enteric nervous system (ENS) which is a complex network of neurons and glial clones. Derived from neural crest cells (NCCs), this little brain controls muscle contraction, motility, and bowel activities in response to stimuli. Failure of developing enteric ganglia at the distal bowel results in intestinal obstruction and Hirschsprung disease (HSCR). This Review summarises the important embryological development of the ENS including proliferation, migration, and differentiation of NCCs. We address the signalling pathways which determine NCC cell fate and discuss how they are altered in the context of HSCR. Finally, we outline the anatomical defects and the mechanisms underlying gut motility in HSCR.

Identification and validation of the common pathogenesis and hub biomarkers in Hirschsprung disease complicated with Crohn’s disease

Background

Although increasing evidence has supported that Hirschsprung disease (HSCR) is the risk factor for children developing Crohn’s disease (CD), the common mechanism of its co-occurrence remains unknown. The purpose of this study is to further explore the underlying mechanism and biomarkers for the co-occurrence of HSCR and CD.

Methods

The Gene Expression Omnibus (GEO) database was used to obtain gene expression profiles for CD (GSE95095) and HSCR (GSE98502). Following the identification of the shared differentially expressed genes (DEGs) of CD and HSCR, functional annotation, protein–protein interaction (PPI) network creation, and module assembly were performed to discover hub genes. RT-qPCR was performed to validate the expression of the hub genes in HSCR samples. The receiver operating characteristic (ROC) curve was utilized to assess the accuracy of the hub genes as biomarkers in predicting CD in both the training dataset and test dataset.

Results

A total of 103 common DEGs (50 downregulated genes and 53 upregulated genes) were chosen for further investigation. The importance of chemokines and cytokines in these two disorders is highlighted by functional analysis. MCODE plug identified three important modules, which functionally enriched the immune system process. Finally, nine hub genes were identified using cytoHubba, including IL1B, IL10, CXCL10, ICAM1, EGR1, FCGR3A, S100A12, S100A9, and FPR1. The nine hub genes were mainly enriched in immune- and inflammation-related pathways. External data profiles and RT-qPCR confirmed the expression of the nine hub genes in HSCR and CD. ROC analysis revealed that the nine hub genes had a strong diagnostic value.

Conclusion

Our study reveals the common pathogenesis of HSCR and CD. These hub genes and diagnostic models may provide novel insight for the diagnosis and treatment of HSCR complicated with CD.

Probiotics for the prevention of Hirschsprung-associated enterocolitis

BACKGROUND

Hirschsprung-associated enterocolitis (HAEC) is a leading cause of serious morbidity and potential mortality in children with Hirschsprung's disease (HD). People with HAEC suffer from intestinal inflammation, and present with diarrhoea, explosive stools, and abdominal distension. Probiotics are live microorganisms with beneficial health effects, which can optimise gastrointestinal function and gut flora. However, the efficacy and safety of probiotic supplementation in the prevention of HAEC remains unclear.

OBJECTIVES

To assess the effects of probiotic supplements used either alone or in combination with pharmacological interventions on the prevention of Hirschsprung-associated enterocolitis.

SEARCH METHODS

We searched CENTRAL, PubMed, Embase, the China BioMedical Literature database (CBM), the World Health Organization International Clinical Trials Registry, ClinicalTrials.gov, the Chinese Clinical Trials Registry, Australian New Zealand Clinical Trials Registry, and Clinical Trials Registry-India, from database inception to 27 February 2022. We also searched the reference lists of relevant articles and reviews for any additional trails.

SELECTION CRITERIA

Randomised controlled trials (RCTs) comparing probiotics and placebo, or any other non-probiotic intervention, for the prevention of HAEC were eligible for inclusion.

DATA COLLECTION AND ANALYSIS

Two review authors independently extracted data and assessed the risk of bias of the included studies; disagreements were resolved by discussion with a third review author. We assessed the certainty of evidence using the GRADE approach. We calculated odds ratios (ORs) with 95% confidence intervals (CIs) for dichotomous outcomes.

MAIN RESULTS

We included two RCTs, with a total of 122 participants. We judged the overall risk of bias as high. We downgraded the evidence due to risk of bias (random sequence generation, allocation concealment, and blinding) and small sample size. The evidence is very uncertain about the effect of probiotics on the occurrence of HAEC (OR 0.58, 95% CI 0.10 to 3.43; I² = 74%; 2 studies, 120 participants; very low-certainty evidence). We found one included study that did not measure serious adverse events and one included study that reported no serious adverse events related to probiotics. Probiotics may result in little to no difference between probiotics and placebo in relation to the severity of children with HAEC at Grade I (OR 0.66, 95% CI 0.14 to 3.16; I² = 25%; 2 studies, 120 participants; low-certainty evidence). The effects of probiotics on the severity of HAEC at Grade II are very uncertain (OR 1.14, 95% CI 0.01 to 136.58; I² = 86%; 2 studies, 120 participants; very low-certainty evidence). Similarly, the evidence suggests that probiotics results in little to no difference in relation to the severity of HAEC at Grade III (OR 0.43, 95% CI 0.05 to 3.45; I² = 0%; 2 studies, 120 participants; low-certainty evidence). No overall mortality or withdrawals due to adverse events were reported. Probiotics may result in little to no difference in the recurrence of episodes of HAEC compared to placebo (OR 0.85, 95% CI 0.24 to 3.00; 1 study, 60 participants; low-certainty evidence).

AUTHORS' CONCLUSIONS

There is currently not enough evidence to assess the efficacy or safety of probiotics for the prevention of Hirschsprung-associated enterocolitis when compared with placebo. The presence of low- to very-low certainty evidence suggests that further well-designed and sufficiently powered RCTs are needed to clarify the true efficacy of probiotics.

Functional Outcomes After Surgery for Total Colonic, Long-Segment, Versus Rectosigmoid Segment Hirschsprung Disease

OBJECTIVES

Knowledge on long-term outcomes in patients with Hirschsprung disease is progressing. Nevertheless, differences in outcomes according to aganglionic lengths are unclear. We compared long-term bowel function and generic quality of life in Hirschsprung patients with total colonic or long-segment versus rectosigmoid aganglionosis.

METHODS

In this nationwide, cross-sectional study participants with proven Hirschsprung disease received the Defecation and Fecal Continence questionnaire, and the Child Health Questionnaire Child Form-87, or the WHO Quality of Life-100. We excluded deceased patients, patients who were younger than 8 years, lived abroad, had a permanent enterostomy, or were intellectually impaired.

RESULTS

The study population (n = 334) was operated for rectosigmoid (83.9%), long-segment (8.7%), or total colonic aganglionosis (7.5%). Fecal incontinence in general was not significantly different between the three groups, but liquid fecal incontinence was significantly associated with total colonic aganglionosis (odds ratio [OR] = 6.00, 95% confidence interval [CI] 2.07-17.38, P = 0.001). Regarding constipation, patients with total colonic or long-segment aganglionosis were less likely to suffer from constipation than the rectosigmoid group (OR = 0.21, 95% CI, 0.05-0.91, P = 0.038 and OR = 0.11, 95% CI, 0.01-0.83, P = 0.032). Quality of life was comparable between the three groups, except for a lower physical score in children with total colonic aganglionosis (P = 0.016).

CONCLUSIONS

Over time Hirschsprung patients with total colonic or long-segment aganglionosis do not suffer from worse fecal incontinence in general. A difference in stool consistency may underlie the association between liquid fecal incontinence and total colonic aganglionosis and constipation in patients with rectosigmoid aganglionosis. Despite these differences, generic quality of life is comparable on reaching adulthood.

Enteric nervous system modulation of luminal pH modifies the microbial environment to promote intestinal health

The enteric nervous system (ENS) controls many aspects of intestinal homeostasis, including parameters that shape the habitat of microbial residents. Previously we showed that zebrafish lacking an ENS, due to deficiency of the sox10 gene, develop intestinal inflammation and bacterial dysbiosis, with an expansion of proinflammatory Vibrio strains. To understand the primary defects resulting in dysbiosis in sox10 mutants, we investigated how the ENS shapes the intestinal environment in the absence of microbiota and associated inflammatory responses. We found that intestinal transit, intestinal permeability, and luminal pH regulation are all aberrant in sox10 mutants, independent of microbially induced inflammation. Treatment with the proton pump inhibitor, omeprazole, corrected the more acidic luminal pH of sox10 mutants to wild type levels. Omeprazole treatment also prevented overabundance of Vibrio and ameliorated inflammation in sox10 mutant intestines. Treatment with the carbonic anhydrase inhibitor, acetazolamide, caused wild type luminal pH to become more acidic, and increased both Vibrio abundance and intestinal inflammation. We conclude that a primary function of the ENS is to regulate luminal pH, which plays a critical role in shaping the resident microbial community and regulating intestinal inflammation.

miR-938 rs2505901 T>C polymorphism increases Hirschsprung disease risk: a case-control study of Chinese children

Aim: To explore the association between miR-938 rs2505901 T>C polymorphism and Hirschsprung disease (HSCR) risk in Chinese children. Materials & Methods: We conducted a case-control study in a Chinese population with 1381 cases and 1457 controls. The associated correlation strengths were assessed by adjusted odds ratios (AORs) and 95% CIs. Results: The results revealed that the rs2505901 TC and rs2505901 TC/CC genotype were related to an increased HSCR risk compared to the risk contributed by the rs2505901 TT genotype. A stratification analysis showed that the rs2505901 TC/CC genotype promoted the progression of HSCR more significantly in patients with the short-segment HSCR subtype. Conclusion: Our study indicated that miR-938 rs2505901 T>C polymorphism is significantly associated with HSCR risk in Chinese children. This result needs to be confirmed with well-designed studies.

Clinical characteristics and validation of diagnosis in individuals with Hirschsprung disease and inflammatory bowel disease

BACKGROUND/PURPOSE

Hirschsprung disease has previously been reported to be associated with inflammatory bowel disease (IBD). The aim was to clinically confirm the diagnosis and to describe characteristics among individuals with both conditions in a national populationbased cohort.

METHODS

Nationwide, population-based cohort study, including all individuals with a Hirschsprung disease diagnosis and an IBD diagnosis registered between 1964 and 2016, in which clinical data were collected from the medical records of 18 validated cases with both Hirschsprung disease and IBD. The medical record of each individual in the study cohort was reviewed for age at IBD diagnosis, type of aganglionosis, type of surgical treatment, subtype of IBD, and treatment for IBD.

RESULTS

Median age at follow up was 34 years (range 19-66), and 3 of 18 indivduals (17%) were females. Median age at first diagnosis of IBD was 21 years (range 10-46). Six patients had ulcerative colitis, ten had Crohn's disease and two had unclassified IBD. Most of the patients had pharmacological treatment for IBD and 5 (28%) individuals had surgical treatment.

CONCLUSION

Hirschsprung disease and IBD was clinically confirmed in 18 cases. Age at IBD onset and subtype of IBD is similar to IBD patients without Hirschsprung disease. Five individuals had undergone surgical treatment for IBD.

Roles of Enteric Neural Stem Cell Niche and Enteric Nervous System Development in Hirschsprung Disease

The development of the enteric nervous system (ENS) is highly modulated by the synchronized interaction between the enteric neural crest cells (ENCCs) and the neural stem cell niche comprising the gut microenvironment. Genetic defects dysregulating the cellular behaviour(s) of the ENCCs result in incomplete innervation and hence ENS dysfunction. Hirschsprung disease (HSCR) is a rare complex neurocristopathy in which the enteric neural crest-derived cells fail to colonize the distal colon. In addition to ENS defects, increasing evidence suggests that HSCR patients may have intrinsic defects in the niche impairing the extracellular matrix (ECM)-cell interaction and/or dysregulating the cellular niche factors necessary for controlling stem cell behaviour. The niche defects in patients may compromise the regenerative capacity of the stem cell-based therapy and advocate for drug- and niche-based therapies as complementary therapeutic strategies to alleviate/enhance niche-cell interaction. Here, we provide a summary of the current understandings of the role of the enteric neural stem cell niche in modulating the development of the ENS and in the pathogenesis of HSCR. Deciphering the contribution of the niche to HSCR may provide important implications to the development of regenerative medicine for HSCR.

The Emerging Genetic Landscape of Hirschsprung Disease and Its Potential Clinical Applications

Hirschsprung disease (HSCR) is the leading cause of neonatal functional intestinal obstruction. It is a rare congenital disease with an incidence of one in 3,500-5,000 live births. HSCR is characterized by the absence of enteric ganglia in the distal colon, plausibly due to genetic defects perturbing the normal migration, proliferation, differentiation, and/or survival of the enteric neural crest cells as well as impaired interaction with the enteric progenitor cell niche. Early linkage analyses in Mendelian and syndromic forms of HSCR uncovered variants with large effects in major HSCR genes including RET, EDNRB, and their interacting partners in the same biological pathways. With the advances in genome-wide genotyping and next-generation sequencing technologies, there has been a remarkable progress in understanding of the genetic basis of HSCR in the past few years, with common and rare variants with small to moderate effects being uncovered. The discovery of new HSCR genes such as neuregulin and BACE2 as well as the deeper understanding of the roles and mechanisms of known HSCR genes provided solid evidence that many HSCR cases are in the form of complex polygenic/oligogenic disorder where rare variants act in the sensitized background of HSCR-associated common variants. This review summarizes the roadmap of genetic discoveries of HSCR from the earlier family-based linkage analyses to the recent population-based genome-wide analyses coupled with functional genomics, and how these discoveries facilitated our understanding of the genetic architecture of this complex disease and provide the foundation of clinical translation for precision and stratified medicine.

Phenotypic spectrum associated with pathogenic mutation in the NRG1 gene in Acadian family

NRG1 is a gene that encodes for a protein that binds to a receptor of the tyrosine kinase family which is essential for the survival of the central nervous system development during embryogenesis. Mutation of the NRG1 gene causes aganglionosis, which leads to Hirschsprung disease. Two brothers of Acadian descent presented with a history of Hirschsprung disease, in association with other anomalies including congenital heart disease, learning difficulties, developmental issues, and hypopigmented hair patch. Molecular analysis in both siblings revealed a heterozygous pathogenic mutation in the NGR1 gene (c.235C>T [p.Arg79*]), that was inherited from an unaffected father. This family expands our knowledge about the phenotypic spectrum associated with pathogenic mutation in the NRG1 gene with intrafamilial variability and the likely reduced penetrance for the phenotypic expression.

Safety and Accuracy of Suction Rectal Biopsy in Preterm Infants

Purpose: Most pediatric surgeons give little attention to the diagnosis of Hirschsprung disease (HD) in preterm infants. We aimed to explore the safety and accuracy of suction rectal biopsy (SRB) for diagnosing HD in preterm infants. Methods: A retrospective review was conducted of 45 preterm patients who underwent SRB from 2015 to 2019 in our hospital. We collected the clinical characteristics and pathology results of the patients and information on follow-up. The sensitivity and specificity of SRB for HD diagnosis were calculated. Results: The median gestational age of the patients was 35 weeks (range: 28.9-36.9 weeks), the median gestational age at biopsy was 38.6 weeks (range: 33.4-60.0 weeks), and the median weight was 2,790 g (range: 1,580-4,100 g). Fifteen patients (33.3%) were positive for HD, which was confirmed after pull-through surgery. Ganglion cells were present in 30 patients. The diagnosis of HD was excluded in 29 patients after discharge follow-up. The sensitivity of SRB ranged from 93.7 to 100%, and the specificity was 100%. No complications occurred after SRB among the patients whose biopsy age was <37 weeks (10 patients) or biopsy weight was <2,000 g (five patients). Conclusion: SRB is accurate and safe for diagnosing HD in late preterm infants.

Whole-genome analysis of noncoding genetic variations identifies multiscale regulatory element perturbations associated with Hirschsprung disease

It is widely recognized that noncoding genetic variants play important roles in many human diseases, but there are multiple challenges that hinder the identification of functional disease-associated noncoding variants. The number of noncoding variants can be many times that of coding variants; many of them are not functional but in linkage disequilibrium with the functional ones; different variants can have epistatic effects; different variants can affect the same genes or pathways in different individuals; and some variants are related to each other not by affecting the same gene but by affecting the binding of the same upstream regulator. To overcome these difficulties, we propose a novel analysis framework that considers convergent impacts of different genetic variants on protein binding, which provides multiscale information about disease-associated perturbations of regulatory elements, genes, and pathways. Applying it to our whole-genome sequencing data of 918 short-segment Hirschsprung disease patients and matched controls, we identify various novel genes not detected by standard single-variant and region-based tests, functionally centering on neural crest migration and development. Our framework also identifies upstream regulators whose binding is influenced by the noncoding variants. Using human neural crest cells, we confirm cell stage-specific regulatory roles of three top novel regulatory elements on our list, respectively in the RET, RASGEF1A, and PIK3C2B loci. In the PIK3C2B regulatory element, we further show that a noncoding variant found only in the patients affects the binding of the gliogenesis regulator NFIA, with a corresponding up-regulation of multiple genes in the same topologically associating domain.

Selective serotonin reuptake inhibitors during pregnancy Do not increase the risk of Hirschsprung disease

PURPOSE

Hirschsprung disease (HSCR) is a multifactorial disease. Maternal intake of selective serotonin reuptake inhibitors (SSRI) during early pregnancy has previously been associated with increased risk for HSCR. The aim of this study was to assess the risk for HSCR in newborns after maternal intake of SSRI in a population-based Swedish cohort.

METHODS

This was a Swedish nationwide, population-based, case-control cohort study containing all children born in Sweden between 1/12006 and 31/122012. The cases were identified in the Swedish National Patient Register and the controls (five age- and sex-matched controls per case) were randomly selected among children without HSCR in the cohort. Data on maternal SSRI use during pregnancy were collected from the Swedish Prescribed Drug Register.

RESULTS

Out of 775,024 born children during the study period, 150 cases of HSCR (112 males) and 750 controls (560 males) were included. Five (3.3%) mothers of newborns with HSCR had used SSRI during pregnancy compared to 16 (2.1%) mothers of the controls (p = 0.372). The mean age was similar in mothers who had used SSRI compared to those who had not (30.9 (SD +/- 5.1) versus 30.6 (SD +/- 5.0), p = 0.81).

CONCLUSIONS

There was no increased risk of HSCR owing to maternal intake of SSRI in this cohort.

LEVEL OF EVIDENCE

Level I.

Weighted Gene Coexpression Network Analysis Reveals the Critical lncRNAs and mRNAs in Development of Hirschsprung's Disease

Hirschsprung's disease (HSCR) is a common newborn defect. This study aimed to identify critical genes involved in the development of HSCR. Differently expressed genes (DEGs) of public data set GSE98502 were analyzed using paired t-test. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analyses were performed using Database for Annotation, Visualization and Integrated Discovery (DAVID) 6.8. Besides, Coexpression network of long noncoding RNAs (lncRNAs)-mRNAs (message RNA) were constructed using weighted gene coexpression network analysis. The key modules were filtered out by calculating the module-trait correlations. Then, hub genes were screened and the expression of these genes was further validated in an independent data set GSE96854. We identified 864 DEGs enriched in 19 GO biological functions such as negative regulation of growth and regulation of heart contraction; 11 KEGG pathways such as mineral absorption and protein digestion and absorption. lncRNAs-mRNAs coexpressed network was constructed, including 8 modules and 177 genes. Hub lncRNAs, including LINC00619, LINC00924, LINC00261, and DRAIC, were identified. Hub mRNAs, including CYCS, CCND1, BDKRB, ITGA6, and TNNC1, were mainly enriched in cancer pathways, p53 signaling pathway, and calcium signaling pathway. The expressions of the hub mRNAs were successfully validated by another independent GSE96854 data set. Our findings indicated the hub lncRNAs, including LINC00619, LINC00924, LINC00261, and DRAIC, as well as hub mRNAs, including CYCS, CCND1, BDKRB, ITGA6, and TNNC1, might involve in the progression of HSCR, and these genes might provide new clinical biomarkers for risk evaluation of HSCR.

Urinary tract anomalies and urinary tract dysfunction in children with Hirschsprung disease-Is follow-up indicated?

BACKGROUND/PURPOSE

Urinary tract function in children with Hirschsprung disease (HD) is rarely considered.

AIM

to evaluate the prevalence of urinary tract anomalies and dysfunction in children with HD compared to controls.

METHODS

This was an observational cross sectional case-control study. Children with HD who underwent transanal endorectal pull-through technique (TERPT) from 2005 to 2017 were invited to participate. Ultrasound of the urinary tract was performed postoperatively. Children >4 years were asked to answer a urinary tract function questionnaire. Controls were age-matched healthy children. Ethical approval was obtained.

RESULTS

Seventy two children with HD and TERPT were included. Ultrasound was performed in 58 children (83%) post-TERPT. Ten anomalies were diagnosed in six children (10%). Structural anomalies included abnormal kidney size (7%), renal agenesis (2%), prominent calyces (2%) and renal pelvis anomaly (25). Probable acquired anomalies included hydronephrosis (2%), hydroureter (2%) and parenchymal damage (2%). One child had a prior nephrectomy owing to a Wilms' tumor. All 37 children >4 years (27 boys and 10 girls), median aged 8 years (range 4-12), answered the questionnaire as did 284 healthy controls (144 boys and 140 girls). Boys with HD reported a higher frequency of enuresis: 65% versus 9% (p = 0.001) and urinary tract infections: 18% versus 3% (p = 0.012). Girls with HD reported enuresis more frequently (60%) than healthy girls (7%) (p = 0.001). Children with HD with constipation reported enuresis more frequently (p = 0.038).

CONCLUSIONS

Urinary tract anomalies and dysfunction deserve attention in the follow-up of children with HD. We suggest screening for urinary tract anomalies and urinary tract symptoms in follow-up of children with HD.

TYPE OF STUDY

Treatment study.

LEVEL

III.

Swedish national population-based study shows an increased risk of depression among patients with Hirschsprung disease

AIM

Hirschsprung disease is usually treated during infancy. The long-term impact on mental health has not been well studied. The aim of this study was to assess the risk for depressive disorders in individuals with Hirschsprung disease.

METHODS

This was a nationwide, population-based cohort study. The study exposure was Hirschsprung disease and the study outcome was depression. The exposed cohort included all individuals with Hirschsprung disease, registered in the Swedish National Patient Register between 1964 and 2013 and the unexposed cohort included ten age- and sex-matched controls per patient. The diagnosis of depression was confirmed by diagnosis in the Swedish National Patient Register.

RESULTS

The cohort included 739 (76.5% males) individuals with Hirschsprung disease and 7390 (76.5% males) controls. Among the patients with Hirschsprung disease, 35 (4.7%) of the patients had had a depressive disorder and 187 (2.5%) of controls, hazard ratio 1.98, 95% confidence interval 1.38-2.84. The mean age at diagnosis of first depression was 21.9 years (SD ± 7) in Hirschsprung disease patients and 23.4 years (SD ± 7), p = 0.236 in the unexposed group. There were no significant gender differences.

CONCLUSION

We found an increased risk of having depressive disorders among individuals with Hirschsprung disease compared to controls.

No increased risk of attention deficit hyperactivity disorders in patients with Hirschsprung disease

PURPOSE

Hirschsprung disease (HSCR) has previously been associated with increased need of special education services despite normal intelligence. The aim of this study was to assess the risk of attention deficit hyperactivity disorders (ADHD) in individuals with HSCR in a population-based cohort.

METHODS

This was a nationwide, population-based cohort study. The study exposure was HSCR and the study outcome was ADHD. The cohort included all individuals with HSCR registered in the Swedish National Patient Register between 1964 and 2013 and ten age- and sex-matched controls per patient, randomly selected from the Population Register.

RESULTS

The cohort comprised 739 individuals with HSCR and 7390 controls. Twenty-six of the 739 individuals with HSCR and 202 of the 7390 controls were diagnosed with ADHD, Odds ratio (OR) 1.30, Confidence interval (CI) 95% 0.84-1.93, indicating no difference in risk for ADHD. The mean age at diagnosis of ADHD was not different between the groups; 18.1 years (SD 8.4) vs 16.7 years (SD 7.8), p = 0.39. Down syndrome did not affect the risk for ADHD, OR 2.26 (CI 95% 0.68-5.53). Female gender decreased the risk for ADHD, OR 0.58 (CI 95% 0.40-0.83).

CONCLUSIONS

There is no increased risk of ADHD in patients with Hirschsprung disease.

LEVEL OF EVIDENCE

Prognosis study, level of evidence: Level I.

Association analysis of NOX5 polymorphisms with Hirschsprung disease

BACKGROUND/PURPOSE

Hirschsprung disease (HSCR) is a developmental disease characterized by the absence of ganglion cells in the intestinal region. NADPH oxidase5 (NOX5) has been identified as one of the possible candidate genes for risk of Hirschsprung disease in our recent genome wide association study (GWAS). In this study, we performed a replication study to analyze the association of NOX5 polymorphisms with HSCR risk and conducted an extended analysis to investigate further associations for sub-groups and haplotypes.

METHODS

A total of 23 NOX5 single nucleotide polymorphisms (SNPs) were genotyped in 187 HSCR patients and 283 unaffected controls. Statistical analysis was performed to examine the effects of genotype on risk of HSCR and HSCR subtype.

RESULTS

Logistic regression analyses revealed that six SNPs (rs59355559, rs62010828, rs34990910, rs11856030, rs311905, and rs8024894) were associated with risk of HSCR (minimum p = 0.007 at rs62010828). Moreover, three SNPs (rs59355559, rs62010828, and rs8024894) were significantly associated with risk of long-segment HSCR (L-HSCR) subtype and 5 SNPs (rs59355559, rs62010828, rs34990910, rs11856030, and rs8024894) were found to be associated with risk of TCA subtype.

CONCLUSION

Our results demonstrate that genetic variants in NOX5 have genetic effects on risk of HSCR, which may serve as useful preliminary information for further study.

LEVELS OF EVIDENCE

Level III of prognosis study.

Expression of BMP-4 and Smad1 in patients with Hirschsprung disease and its clinical significance

Expression and clinical significance of bone morphogenetic protein (BMP)-4 and Smad1 in patients with Hirschsprung disease (HD) were investigated. A retrospective analysis of 96 HD patients (experimental group) admitted to Xuzhou Children's Hospital, Xuzhou Medical University from June 2015 to June 2017 was performed. According to the samples, the experimental group was divided into the stenosis group, the transition group and the expansion group. Forty-seven children with colostomy due to intestinal obstruction were selected as the control group. The expression levels of BMP-4 and Smad1 proteins were detected by immunohistochemical staining. The expression levels of BMP-4 and Smad mRNA were detected by real-time quantitative PCR (RT-qPCR), and were quantified and compared. Via immunohistochemistry, BMP-4 and Smad1 proteins were detected in the samples of different parts of HD patients and children with intestinal obstruction. The positive expression levels of BMP-4 and Smad1 proteins in the transition group were decreased compared with those in the expansion and control groups (P<0.05), and the positive expression levels of BMP-4 and Smad1 proteins in the stenosis group were decreased compared with those in the transition, expansion, and control groups (P<0.05). Also, the gene expression levels of BMP-4 and Smad1 in the transition and stenosis groups were successively decreased, and the differences were statistically significant (P<0.05). In conclusion, the expression of BMP-4 and Smad1 in the intestinal plexus of HD lesions was significantly reduced, indicating that BMP-4 and Smad1 are closely related to the occurrence of HD, and it is suspected that they have a certain influence on the intestinal development of congenital digestive tract malformations.

Congenital intestinal stenosis and Hirschsprung's disease: two extremely rare pathologies in a newborn puppy

Background

Hirschsprung’s disease (HSCR) is a common congenital malformation of the enteric nervous system (ENS). During fetal development, ganglion cells of the ENS are derived from neural crest cells that migrate to the bowel. These cells reside principally in two ganglionated plexus: 1) The myenteric plexus, extending from the esophagus to the anus, and 2) submucous plexus, extending from the duodenum to the anus. In large animal species, there is a third plexus called Henle’s or Schabadasch’s plexus.

ENS ganglion cells play a key role in normal gastrointestinal motility, respond to sensory stimuli and regulate blood flow. Both plexus show a high degree of independence from the central nervous system. Alterations in the embryonic development of the ENS can induce multiple pathologies in animal models and humans.

Case presentation

The present case was a female the fifth born in a litter of 5 puppies. At about 2–3 weeks of age, she suffered from abdominal distension, pain, and constipation. At approximately 8–10 weeks of age, the puppy started to vomit abundantly, and the regurgitated food appeared undigested. Progressive abdominal distention was observed, with quite visible peristaltic movements and more frequent vomiting episodes. The abdominal radiographs, based on AP and side projections, revealed an enlargement of the abdominal diameter and an increased width in the epigastric region. At 12 weeks of age, exploratory surgery revealed a stenotic segment in the jejunum, followed by a small transition zone and then a significantly reduced diameter. Immunohistochemical examinations were performed using antibodies against calretinin, S-100 protein, CD56, neuron specific enolase (NSE) and synaptophysin, which are the biological markers for diagnosing HSCR.

Conclusion

A reduced number of ganglion cells (1–3 cells per ganglion) were found. There was no specific staining pattern for many of these; while for others, the pattern was compatible with HSCR. Surgical intervention to remove the stenotic section prolonged the life of the puppy for 13 years. Extremely rare pathologies such as that discussed herein should be studied to understand the pathophysiology and be able to diagnose small species in veterinary medicine in a timely fashion. To our knowledge, this is the first report of congenital intestinal stenosis and Hirschprung’s disease in a newborn puppy.

Electronic supplementary material

The online version of this article (10.1186/s12917-019-1806-z) contains supplementary material, which is available to authorized users.

Identification of Genes Associated With Hirschsprung Disease, Based on Whole-Genome Sequence Analysis, and Potential Effects on Enteric Nervous System Development

BACKGROUND & AIMS

Hirschsprung disease, or congenital aganglionosis, is believed to be oligogenic-that is, caused by multiple genetic factors. We performed whole-genome sequence analyses of patients with Hirschsprung disease to identify genetic factors that contribute to disease development and analyzed the functional effects of these variants.

METHODS

We performed whole-genome sequence analyses of 443 patients with short-segment disease, recruited from hospitals in China and Vietnam, and 493 ethnically matched individuals without Hirschsprung disease (controls). We performed genome-wide association analyses and gene-based rare-variant burden tests to identify rare and common disease-associated variants and study their interactions. We obtained induced pluripotent stem cell (iPSC) lines from 4 patients with Hirschsprung disease and 2 control individuals, and we used these to generate enteric neural crest cells for transcriptomic analyses. We assessed the neuronal lineage differentiation capability of iPSC-derived enteric neural crest cells using an in vitro differentiation assay.

RESULTS

We identified 4 susceptibility loci, including 1 in the phospholipase D1 gene (PLD1) (P = 7.4 × 10^-7). The patients had a significant excess of rare protein-altering variants in genes previously associated with Hirschsprung disease and in the β-secretase 2 gene (BACE2) (P = 2.9 × 10^-6). The epistatic effects of common and rare variants across these loci provided a sensitized background that increased risk for the disease. In studies of the iPSCs, we observed common and distinct pathways associated with variants in RET that affect risk. In functional assays, we found variants in BACE2 to protect enteric neurons from apoptosis. We propose that alterations in BACE1 signaling via amyloid β precursor protein and BACE2 contribute to pathogenesis of Hirschsprung disease.

CONCLUSIONS

In whole-genome sequence analyses of patients with Hirschsprung disease, we identified rare and common variants associated with disease risk. Using iPSC cells, we discovered some functional effects of these variants.

Epidemiological characteristics of Hirschsprung's disease (HSCR): Results of a case series of fifty patients from Bangladesh

BACKGROUND

The epidemiology of Hirschsprung's disease (HSCR) in Bangladesh has never been studied. The aim of this study was to determine the epidemiological characteristics of HSCR in Bangladesh.

METHODS

Data from fifty patients were collected prospectively from two hospitals in Chittagong, Bangladesh.

RESULTS

The rate of consanguinity (16%) among parents of HSCR patients was higher than that of the general population (10%). Maternal age at the time of birth of the affected child was ≤30years in all cases except one. No association was found between parents' occupation and HSCR. No patient was born preterm and only three patients (6%) had low birth weight. Nine patients (18%) had associated anomalies. We found coexistence of bilateral accessory tragi and ankyloglossia in one patient, and coexistence of rectal duplication cyst in another. Neither anomaly had been previously reported in HSCR patients.

CONCLUSIONS

Our study suggests that consanguinity might increase the risk of HSCR whereas advanced maternal age does not. HSCR patients were found more likely to born at term and with normal birth weight. The coexistence of HSCR with previously unreported anomalies highlights the diversity of conditions that can co-occur with HSCR.

LEVELS OF EVIDENCE

IV.

NRG1 variant effects in patients with Hirschsprung disease

Background

Hirschsprung disease (HSCR) is a heterogeneous genetic disorder characterized by absence of ganglion cells along the intestines resulting in functional bowel obstruction. Mutations in neuregulin 1 (NRG1) gene have been implicated in some cases of intestinal aganglionosis. This study aims to investigate the contribution of the NRG1 gene to HSCR development in an Indonesian population.

Methods

We analyzed the entire coding region of the NRG1 gene in 54 histopathologically diagnosed HSCR patients.

Results

All patients were sporadic non-syndromic HSCR with 53/54 (98%) short-segment and 1/54 (2%) long-segment patients. NRG1 gene analysis identified one rare variant, c.397G > C (p.V133 L), and three common variants, rs7834206, rs3735774, and rs75155858. The p.V133 L variant was predicted to reside within a region of high mammalian conservation, overlapping with the promoter and enhancer histone marks of relevant tissues such as digestive and smooth muscle tissues and potentially altering the AP-4_2, BDP1_disc3, Egr-1_known1, Egr-1_known4, HEN1_2 transcription factor binding motifs. This p.V133 L variant was absent in 92 non-HSCR controls. Furthermore, the rs7834206 polymorphism was associated with HSCR by case–control analysis (p = 0.037).

Conclusions

This study is the first report of a NRG1 rare variant associated with HSCR patients of South-East Asian ancestry and provides further insights into the contribution of NRG1 in the molecular genetic pathogenesis of HSCR.

Electronic supplementary material

The online version of this article (10.1186/s12887-018-1265-x) contains supplementary material, which is available to authorized users.

The advances of genetics research on Hirschsprung's disease

Hirschsprung's disease (HSCR) is a rare and complex congenital disorder characterized by the absence of the enteric neurons in lower digestive tract with an incidence of 1/5 000. Affected infant usually suffer from severe constipation with megacolon and distended abdomen, and face long-term complications even after surgery. In the last 2 decades, great efforts and progresses have been made in understanding the genetics and molecular biological mechanisms that underlie HSCR. However, only a small fraction of the genetic risk can be explained by the identified mutations in the previously established genes. To search novel genetic alterations, new study designs with advanced technologies such as genome/exome-wide association studies (GWASs/EWASs) and next generation sequencing (NGS) on target genes or whole genome/exome, were applied to HSCR. In this review, we summaries the current development of the genetics researches on HSCR based on GWASs/EWASs and NGS, focusing on the newly discovered variants and genes, and their potential roles in HSCR pathogenesis.

Gene expression profiling coupled with Connectivity Map database mining reveals potential therapeutic drugs for Hirschsprung disease

BACKGROUND

Hirschsprung disease (HD) is a congenital intestinal anomaly resulting from a failure to form enteric ganglia in the lower bowel. Surgery is the main therapeutic strategy, although neural stem cell transplantation has recently shown promise. However, HD remains a challenging disorder to treat. Our aim was to identify drugs that could counteract the dysregulated pathways in HD and could thus be potential novel therapies.

METHODS

We used microarray analysis to identify genes differentially expressed in ganglionic and aganglionic bowel samples from eight children with HD. The signature of differentially expressed genes was then used as a search query to explore the Connectivity Map (cMAP), a transcriptional expression database that catalogs gene signatures elicited by chemical perturbagens.

RESULTS

We uncovered several dysregulated signaling pathways, and in particular regulation of neuron development, in HD. The cMAP search identified some compounds with the potential to counteract the effects of the dysregulated molecular signature in this disease. One of these, pepstatin A, was recently shown to rescue the migration defects observed in a mouse model of HD, providing strong support for our findings.

CONCLUSIONS

This study advances our understanding of the molecular changes in HD and identifies several potential pharmacological interventions. Further testing of the identified compounds is warranted.

Common genetic variants in GAL, GAP43 and NRSN1 and interaction networks confer susceptibility to Hirschsprung disease

Hirschsprung disease (HSCR) is a severe multifactorial genetic disorder. Microarray studies indicated GAL,GAP43 and NRSN1 might contribute to the altered risk in HSCR. Thus, we focused on genetic variations in GAL,GAP43 and NRSN1, and the gene‐gene interactions involved in HSCR susceptibility. We recruited a strategy combining case‐control study and MassArray system with interaction network analysis. For GAL,GAP43 and NRSN1, a total of 18 polymorphisms were assessed in 104 subjects with sporadic HSCR and 151 controls of Han Chinese origin. We found statistically significant differences between HSCR and control groups at 5 genetic variants. For each gene, the haplotypes combining all polymorphisms were the most significant. Based on SNPsyn, MDR and GeneMANIA analyses, we observed significant gene‐gene interactions among GAL,GAP43,NRSN1 and our previous identified RELN,GABRG2 and PTCH1. Our study for the first time indicates that genetic variants within GAL,GAP43 and NRSN1 and related gene‐gene interaction networks might be involved in the altered susceptibility to HSCR in the Han Chinese population, which might shed more light on HSCR pathogenesis.

Increased Risk of Inflammatory Bowel Disease in a Population-based Cohort Study of Patients With Hirschsprung Disease

OBJECTIVES

Hirschsprung disease (HSCR) has previously been associated with inflammatory bowel disease (IBD). There are no data to show how common this association is. The aim of the present study was to assess the risk of IBD in individuals with HSCR in a population-based cohort.

METHODS

This was a nationwide, population-based cohort study. The study exposure was HSCR and the study outcome was IBD. The cohort included all individuals with HSCR registered in the Swedish National Patient Register between 1964 and 2013 and 10 age- and sex-matched controls per patient, randomly selected from the Swedish Population Register. Individuals with IBD were identified in the Swedish National Patient Register. Data were validated by checking for relevant surgical procedures, and, or prescription of drugs for IBD registered in the Swedish Drug Registry.

RESULTS

The cohort comprised 739 individuals with HSCR (565 boys) and 7390 controls (5650 boys). The median age at diagnosis of IBD was not different between the groups; 19 years (5-34) versus 21 years (7-37), P = 0.21. Twenty of the 739 individuals with HSCR and 41 of the 7390 controls had IBD, odds ratio 4.99, and 95% confidence interval 2.85 to 8.45. In the exposed group, 15 individuals had Crohn disease and 5 ulcerative colitis at their latest admission compared to 18 individuals with Crohn disease and 23 with ulcerative colitis in the unexposed group, P = 0.030.

CONCLUSION

There is an increased risk of IBD in patients with HSCR, which should be considered in clinical practice.

Are all patients with short segment Hirschsprung's disease equal? A retrospective multicenter study

BACKGROUND/PURPOSE

Short segment Hirschsprung's disease (HSCR) carries a better prognosis than long segment disease, but the definition of short is controversial. The objective of this study is to determine anatomically the extent of disease involvement that would be associated with a better functional outcome.

METHODS

This is a retrospective multicenter (n = 3) study with patients (≥ 3 years) who had transanal pullthrough operation done for aganglionosis limited to the recto-sigmoid colon were reviewed. The extent of disease involvement and bowel resection was retrieved by reviewing the operative records as well as histopathological reports of the resected specimens. Clinical assessment was performed according to the criteria of a seven-itemed bowel function score (BFS) (maximum score = 20). Manometric assessment was performed with anorectal manometry.

RESULTS

The study period started from 2003 to 45 patients were studied with median age at assessment = 52.0 months and operation = 3.0 months. The disease involvement was categorized into upper sigmoid-descending colon (DC) (n = 8), sigmoid colon (SC) (n = 12), upper rectum (UR) (n = 14) and lower rectum (LR) (n = 11) according to the level of normal biopsy result. There was no significant difference in the age of assessment between the four groups. The median BFSs in the DC, SC, UR and LR were 13, 15, 17 and 17, respectively (p = 0.01). Nine patients from the DC and SC groups reported soiling for more than twice per week. Sub-group analysis comparing patients with and without the entire sigmoid colon resected revealed worse functional outcomes in terms of the incidence of soiling (40.7 vs 22.2%, p = 0.05) and the BFS (14 vs 18, p = 0.04) in the former group. Anorectal manometry did not reveal any significant difference between the four groups, but a higher proportion of patients in the UR and LR groups appeared to have a normal sphincter resting pressure (DC vs SC vs UR vs LR = 62.5 vs 75.0 vs 85.7 vs 80.0%, p = 0.10).

CONCLUSION

Patients with short segment HSCR are not equal at all. HSCR patients with aganglionosis limited to the rectum without the need of removing the entire sigmoid colon have a better bowel control and overall functional score. Less bowel loss and colonic dissection maybe the underlying reasons. Although future studies with a larger sample size and a longer follow-up period are required to validate the results of this study, it has provided a new insight to the current understanding of short segment disease in HSCR.

Down-regulation of fibronectin and the correlated expression of neuroligin in hirschsprung disease

AIM

The goal of this study was to investigate the expression of fibronectin (FN) and the correlated abundance of neuroligins (NLs) in the enteric nervous system (ENS) and to find a novel diagnostic marker in the serum of Hirschsprung disease (HSCR) patients.

METHODS

The expression levels of FN, neuroligin-1 and neuroligin-2 were detected in 114 children with or without HSCR. The expression and localization of the NLs and FN were assessed morphologically by immunohistochemical staining. Western blot analysis and real-time fluorescence quantitative PCR (qPCR) were performed to examine the correlated expression of the NLs and FN in aganglionic, transitional, and normal ganglionic colon tissues. An enzyme-linked immunosorbent assay (ELISA) was performed to evaluate and compare serum FN levels between HSCR and non-HSCRand between long-type HSCR and short-type HSCR.

RESULTS

These studies showed that both neuroligin-1 and neuroligin-2 were expressed at low levels in aganglionic segments and at intermediate levels in transitional segments compared to their high level of expression in normal tissue. In contrast, FN expression was negatively correlated, with expression in these three samples transitioning from highest to lowest. The serum FN level was higher in HSCR than in non-HSCR, but no significant difference between short-type HSCR and long-type HSCR was observed.

CONCLUSION

FN affects the expression of both neuroligin-1 and neuroligin-2 in HSCR, which may lead to the hypoplasia of ganglion cells in the ENS. This correlation may play a key role in the pathogenesis, diagnosis, or classification of HSCR.

Mortality in Swedish patients with Hirschsprung disease

PURPOSE

Hirschsprung disease (HSCR) has previously been associated with increased mortality. The aim of this study was to assess mortality in patients with Hirschsprung disease in a population-based cohort.

METHODS

This was a nationwide, population-based cohort study. The study exposure was HSCR and the study outcome was death. The cohort included all individuals with HSCR registered in the Swedish National Patient Register between 1964 and 2013 and ten age- and sex-matched controls per patient, randomly selected from the Population Register. Mortality and cause of death were assessed using the Swedish National Causes of Death Register.

RESULTS

The cohort comprised 739 individuals with HSCR (565 male) and 7390 controls (5650 male). Median age of the cohort was 19 years (range 2-49). Twenty-two (3.0%) individuals with HSCR had died at median age 2.5 years (range 0-35) compared to 49 (0.7%) controls at median age 20 years (0-44), p < 0.001. Hazard ratio for death in HSCR patients compared to healthy controls was 4.77 (confidence interval (CI) 95% 2.87-7.91), and when adjusted for Down syndrome, the hazard ratio was 3.6 (CI 95% 2.04-6.37).

CONCLUSIONS

The mortality rate in the HSCR cohort was 3%, which was higher than in controls also when data were adjusted for Down syndrome.

Hirschsprung disease-Bowel function beyond childhood

Hirschsprung disease is a developmental defect of the enteric nervous system characterized by lack of enteric neurons in the distal hindgut. There are numerous reports on short-term outcomes indicating that impaired bowel function is common. Recently, several controlled studies show that bowel function outcomes are affected beyond childhood, in adolescents and adults, compared with healthy control subjects. Constipation and fecal incontinence are common. The impaired bowel function appears to have a negative impact on quality of life, although, a majority of patients have adapted to their symptoms. On the other hand, Hirschsprung disease seems to have limited impact on education and occupation in adult life. The aim of this review was to summarize current knowledge of bowel function outcome beyond childhood in patients with Hirschsprung disease.

Advances in paediatric gastroenterology

Recent developments in paediatric gastrointestinal surgery have focused on minimally invasive surgery, the accumulation of high-quality clinical evidence, and scientific research. The benefits of minimally invasive surgery for common disorders like appendicitis and hypertrophic pyloric stenosis are all supported by good clinical evidence. Although minimally invasive surgery has been extended to neonatal surgery, it is difficult to establish its role for neonatal disorders such as oesophageal atresia and biliary atresia through clinical trials because of the rarity of these disorders. Advances in treatments for biliary atresia and necrotising enterocolitis have been achieved through specialisation, multidisciplinary management, and multicentre collaboration in research; similarly robust clinical evidence for other rare gastrointestinal disorders is needed. As more neonates with gastrointestinal diseases survive into adulthood, their long-term sequelae will also need evidence-based multidisciplinary care. Identifying cures for long-term problems of a complex developmental anomaly such as Hirschsprung's disease will rely on unravelling its pathogenesis through genetics and the development of stem-cell therapy.

Hirschsprung's disease in twins: a systematic review and meta-analysis

AIM OF THE STUDY

Hirschsprung's disease (HSCR) is known to occur in families. The reported overall incidence of familial cases is 7.6%, with a higher incidence of 15-21% in total colonic aganglionosis and 50% in the rare total intestinal aganglionosis. HSCR is extremely rare in twins. The aim of this study was to systematically analyse the patterns of HSCR in twins published in the literature.

METHODS

Electronic databases Pubmed and Medline were screened for relevant articles using the keywords "Hirschsprung's disease", "aganglionosis", "twins", "monozygotic", and "dizygotic". Examining reference lists identified further relevant papers.

MAIN RESULTS

Twelve studies with a total of 18 twin pairs were included in this analysis. 67% twins were discordant. HSCR was found in 24 out of 36 twin subjects (67%), of which 83% affected were male. Rectosigmoid type was reported in 71% of patients, long-segment disease in 21, and 8% presented with a total aganglionosis. Three twin pairs had at least one family member affected with HSCR.

CONCLUSION

HSCR was found in two-thirds of twin subjects with a male predominance. Rectosigmoid aganglionosis was the most common variant. Disease discordance was identified, where environmental insults were postulated to be predisposing factors to disease expression. Future studies investigating the disease-associated mutations in the already identified HSCR genes should provide insights into the genetic basis of HSCR in twins.

Trans-ethnic meta-analysis of genome-wide association studies for Hirschsprung disease

Hirschsprung disease (HSCR) is the most common cause of neonatal intestinal obstruction. It is characterized by the absence of ganglia in the nerve plexuses of the lower gastrointestinal tract. So far, three common disease-susceptibility variants at the RET, SEMA3 and NRG1 loci have been detected through genome-wide association studies (GWAS) in Europeans and Asians to understand its genetic etiologies. Here we present a trans-ethnic meta-analysis of 507 HSCR cases and 1191 controls, combining all published GWAS results on HSCR to fine-map these loci and narrow down the putatively causal variants to 99% credible sets. We also demonstrate that the effects of RET and NRG1 are universal across European and Asian ancestries. In contrast, we detected a European-specific association of a low-frequency variant, rs80227144, in SEMA3 [odds ratio (OR) = 5.2, P = 4.7 × 10-10]. Conditional analyses on the lead SNPs revealed a secondary association signal, corresponding to an Asian-specific, low-frequency missense variant encoding RET p.Asp489Asn (rs9282834, conditional OR = 20.3, conditional P = 4.1 × 10-14). When in trans with the RET intron 1 enhancer risk allele, rs9282834 increases the risk of HSCR from 1.1 to 26.7. Overall, our study provides further insights into the genetic architecture of HSCR and has profound implications for future study designs.

Genetic Background of Hirschsprung Disease: A Bridge Between Basic Science and Clinical Application

Hirschsprung's disease (HSCR) is a congenital disorder, defined by partial or complete loss of the neuronal ganglion cells in the intestinal tract, which is caused by the failure of neural crest cells to migrate completely during intestinal development during fetal life. HSCR has a multifactorial etiology, and genetic factors play a key role in its pathogenesis; these include mutations within several gene loci. These have been identified by screening candidate genes, or by conducting genome wide association (GWAS) studies. However, only a small portion of them have been proposed as major genetic risk factors for the HSCR. In this review, we focus on those genes that have been identified as either low penetrant or high penetrant variants that determine the risk of Hirschsprung's disease. J. Cell. Biochem. 119: 28-33, 2018. © 2017 Wiley Periodicals, Inc.

Effects of RET, NRG1 and NRG3 Polymorphisms in a Chinese Population with Hirschsprung Disease

The RET proto-oncogene was identified as a major locus involved in Hirschsprung disease (HSCR). A genome-wide association study (GWAS) and whole exome sequencing identified NRG1 and NRG3 as additional HSCR susceptibility loci. We investigated the effects of RET (rs2506030 and rs2435357), NRG1 (rs2439302, rs16879552 and rs7835688) and NRG3 (rs10748842, rs10883866 and rs6584400) polymorphisms in a Chinese population with HSCR. We assessed single nucleotide polymorphisms (SNPs) in the RET, NRG1 and NRG3 genes in a cohort of 362 sporadic HSCR patients and 1,448 normal controls using a TaqMan genotyping assay. Significant associations were found between HSCR risk and rs2506030, rs2435357, rs2439302 and rs7835688 (odds ratio [OR] 1.64, P = 1.72E-06; 2.97, P = 5.15E-33; 1.84, P = 9.36E-11; and 1.93, P = 1.88E-12, respectively). Two locus analyses of SNPs indicated increased disease risks of HSCR between NRG1 rs2439302 and RET rs2435357 or rs2506030. RET rs2506030 (GG genotype) and rs2435357 (TT genotype), in combination with NRG1 rs2439302 (GG genotype), were strongly associated with the highest risk of HSCR (OR = 56.53, P = 4.50E-07) compared with the two loci or a single SNP of either RET or NRG1. Our results support the association between genetic variation of RET and NRG1 and susceptibility to HSCR in the Chinese population.

Hirschsprung's disease: clinical dysmorphology, genes, micro-RNAs, and future perspectives

On the occasion of the 100th anniversary of Dr. Harald Hirschsprung's death, there is a worldwide significant research effort toward identifying and understanding the role of genes and biochemical pathways involved in the pathogenesis as well as the use of new therapies for the disease harboring his name (Hirschsprung disease, HSCR). HSCR (aganglionic megacolon) is a frequent diagnostic and clinical challenge in perinatology and pediatric surgery, and a major cause of neonatal intestinal obstruction. HSCR is characterized by the absence of ganglia of the enteric nervous system, mostly in the distal gastrointestinal tract. This review focuses on current understanding of genes and pathways associated with HSCR and summarizes recent knowledge related to micro RNAs (miRNAs) and HSCR pathogenesis. While commonly sporadic, Mendelian patterns of inheritance have been described in syndromic cases with HSCR. Although only half of the patients with HSCR have mutations in specific genes related to early embryonic development, recent pathway-based analysis suggests that gene modules with common functions may be associated with HSCR in different populations. This comprehensive profile of functional gene modules may serve as a useful resource for future developmental, biochemical, and genetic studies providing insights into the complex nature of HSCR.

Potential association of VAMP5 polymorphisms with total colonic aganglionosis in Hirschsprung disease

BACKGROUND

Hirschsprung disease (HSCR) is a congenital bowel disease caused by the absence of nerve cells in portions of the intestine. Our recent genome-wide association study has identified a variant (rs1254900) of vesicle-associated membrane protein 5 (VAMP5) as a potential risk locus for total colonic aganglionosis (TCA) in HSCR. In addition, VAMP5 is a member of the VAMP/synaptobrevin protein complex, which participates in nerve signal transduction by regulating the vesicular fusion of the neurotransmitter in synaptic transmission.

METHODS

A total of 11 single nucleotide polymorphisms (SNPs), including those in the functionally important coding region, were selected on the basis of linkage disequilibrium and genotyped in 187 HSCR patients and 283 unaffected controls by using a TaqMan assay. Logistic analysis was conducted to investigate the possible association between VAMP5 SNPs and the risk of HSCR.

KEY RESULTS

Genetic variants of VAMP5 showed increased association signals in the TCA subgroup of HSCR patients (minimum p = 9.69 × 10(-5) , OR = 3.93 at rs10206961) compared to other subgroups, even after Bonferroni correction (pcorr = 0.002). In haplotype analysis, three haplotypes (BL1_ht1, BL2_ht1, and BL2_ht2) were associated with the risk of TCA (minimum pcorr = 0.005). In additional combined analysis after imputation based on our previous GWAS, five SNPs still retained significant associations with the TCA subtype (minimum pcorr = 0.006 at rs10206961).

CONCLUSIONS & INFERENCES

Considering that differential genetic effects on the development of the enteric nervous system, our results suggest that VAMP5 may be associated with the TCA of HSCR. However, further replications and functional evaluations are required.

Maternal Risk Factors and Perinatal Characteristics for Hirschsprung Disease

BACKGROUND AND OBJECTIVES

Hirschsprung disease (HSCR) is a congenital defect of the enteric nervous system characterized by a lack of ganglion cells in the distal hindgut. The aim of this study was to assess the birth prevalence, perinatal characteristics, and maternal risk factors in HSCR patients in Sweden.

METHODS

This was a nationwide, population-based, case-control study of all children born in Sweden between 1982 and 2012 and registered in the Swedish Medical Birth Register. Cases were identified in the Swedish National Patient Register and data on potential maternal risk factors and patient characteristics were collected from the Swedish National Patient Register and the Swedish Medical Birth Register. Five age- and sex-matched controls were randomly selected for each case. The association between studied risk factors and HSCR was analyzed using conditional logistic regression to calculate the odds ratio (OR) and 95% confidence interval (CI).

RESULTS

The study population comprised 600 HSCR cases and 3000 controls with a male-to-female ratio of 3.7:1. The birth prevalence of HSCR was 1.91/10 000. Maternal obesity was associated with an increased risk for the child to have HSCR (OR 1.74; CI 1.25-2.44). Children with HSCR were born at an earlier gestational age (OR 1.60; CI 1.18-2.17) than control children. Associated malformations were identified in 34.5% of the cases.

CONCLUSIONS

This study showed that the Swedish birth prevalence of HSCR was 1.91/10 000. Children with HSCR disease were born at a lower gestational age than controls. Maternal obesity may increase the risk for the child to have HSCR.

Prospective identification and culture of rat enteric neural stem cells (ENSCs)

Hirschprung's disease (HD), a very common congenital abnormality in children, occurs mainly due to the congenital developmental defect of the enteric nervous system. The absence of enteric ganglia from the distal gut due to deletion in gut colonization by neural crest progenitor cells may lead to HD. The capacity to identify and isolate the enteric neuronal precursor cells from developing and mature tissues would enable the development of cell replacement therapies for HD. However, a mature method to culture these cells is a challenge. The present study aimed to propose a method to culture enteric neural stem cells (ENSCs) from the DsRed transgenic fetal rat gut. The culture medium used contained 15 % chicken embryo extract, basic fibroblast growth factor, and epidermal growth factor. ENSCs were cultured from embryonic day 18 in DsRed transgenic rat. Under inverted microscope and fluorescence staining, ENSCs proliferated to form small cell clusters on the second day of culture. The neurospheres-like structure were suspended in the medium, and there were some filaments between the adherent cells from day 3 to day 6 of the culture. The neurospheres were formed by ENSCs on day 8 of the culture. Network-like connections were formed between the adherent cells and differentiated cells after adding 10 % FBS. The differentiated cells were positive for neurofilament and glial fibrillary acidic protein antibodies. The present study established a method to isolate and culture ENSCs from E18 DsRed transgenic rats in the terminal stage of embryonic development. This study would offer a way to obtain plenty of cells for the future research on the transplantation of HD.

Zebrafish as a model for understanding enteric nervous system interactions in the developing intestinal tract

The enteric nervous system (ENS) forms intimate connections with many other intestinal cell types, including immune cells and bacterial consortia resident in the intestinal lumen. In this review, we highlight contributions of the zebrafish model to understanding interactions among these cells. Zebrafish is a powerful model for forward genetic screens, several of which have uncovered genes previously unknown to be important for ENS development. More recently, zebrafish has emerged as a model for testing functions of genes identified in human patients or large-scale human susceptibility screens. In several cases, zebrafish studies have revealed mechanisms connecting intestinal symptoms with other, seemingly unrelated disease phenotypes. Importantly, chemical library screens in zebrafish have provided startling new insights into potential effects of common drugs on ENS development. A key feature of the zebrafish model is the ability to rear large numbers of animals germ free or in association with only specific bacterial species. Studies utilizing these approaches have demonstrated the importance of bacterial signals for normal intestinal development. These types of studies also show how luminal bacteria and the immune system can contribute to inflammatory processes that can feedback to influence ENS development. The excellent optical properties of zebrafish embryos and larvae, coupled with the ease of generating genetically marked cells of both the host and its resident bacteria, allow visualization of multiple intestinal cell types in living larvae and should promote a more in-depth understanding of intestinal cell interactions, especially interactions between other intestinal cell types and the ENS.

Deriving human ENS lineages for cell therapy and drug discovery in Hirschsprung disease

The enteric nervous system (ENS) is the largest component of the autonomic nervous system, with neuron numbers surpassing those present in the spinal cord. The ENS has been called the 'second brain' given its autonomy, remarkable neurotransmitter diversity and complex cytoarchitecture. Defects in ENS development are responsible for many human disorders including Hirschsprung disease (HSCR). HSCR is caused by the developmental failure of ENS progenitors to migrate into the gastrointestinal tract, particularly the distal colon. Human ENS development remains poorly understood owing to the lack of an easily accessible model system. Here we demonstrate the efficient derivation and isolation of ENS progenitors from human pluripotent stem (PS) cells, and their further differentiation into functional enteric neurons. ENS precursors derived in vitro are capable of targeted migration in the developing chick embryo and extensive colonization of the adult mouse colon. The in vivo engraftment and migration of human PS-cell-derived ENS precursors rescue disease-related mortality in HSCR mice (Ednrb(s-l/s-l)), although the mechanism of action remains unclear. Finally, EDNRB-null mutant ENS precursors enable modelling of HSCR-related migration defects, and the identification of pepstatin A as a candidate therapeutic target. Our study establishes the first, to our knowledge, human PS-cell-based platform for the study of human ENS development, and presents cell- and drug-based strategies for the treatment of HSCR.

Hirschsprung's disease: A bridge for science and surgery

BACKGROUND/PURPOSE

Understanding the true nature of the disease provided the basis for appropriate surgery for Hirschsprung's disease some 60 years ago. Nevertheless, surgical outcome remains unsatisfactory. Advances in diagnosis and treatment will depend on the elucidation of the pathogenesis and disease heterogeneity.

METHODS

This lecture outlines the author's attempt in the past 30 years to bridge some of the gaps of knowledge in Hirschsprung's disease.

RESULTS

Studies of human fetal gut and aganglionic gut gave insight into the complexity of the human enteric nervous system, but the more fruitful studies came from genetic studies in which disease-causing genes were discovered, and the importance of noncoding mutations conferring disease susceptibility was unraveled. Animal models and pluripotent stem cell studies allowed elucidation of the interacting gene-cell-microenvironment signaling pathways for neural crest proliferation, migration, and differentiation.

CONCLUSION

Hirschsprung's disease has been a bridge for science and surgery. An integrative approach could provide breakthroughs in the diagnosis and treatment strategies of this complex condition, leading to improved outcome.

DIDA: A curated and annotated digenic diseases database

DIDA (DIgenic diseases DAtabase) is a novel database that provides for the first time detailed information on genes and associated genetic variants involved in digenic diseases, the simplest form of oligogenic inheritance. The database is accessible via http://dida.ibsquare.be and currently includes 213 digenic combinations involved in 44 different digenic diseases. These combinations are composed of 364 distinct variants, which are distributed over 136 distinct genes. The web interface provides browsing and search functionalities, as well as documentation and help pages, general database statistics and references to the original publications from which the data have been collected. The possibility to submit novel digenic data to DIDA is also provided. Creating this new repository was essential as current databases do not allow one to retrieve detailed records regarding digenic combinations. Genes, variants, diseases and digenic combinations in DIDA are annotated with manually curated information and information mined from other online resources. Next to providing a unique resource for the development of new analysis methods, DIDA gives clinical and molecular geneticists a tool to find the most comprehensive information on the digenic nature of their diseases of interest.

Knockout mouse models of Hirschsprung's disease

PURPOSE

Hirschsprung's disease (HSCR) is a developmental disorder of the enteric nervous system, which occurs due to the failure of neural crest cell migration. Rodent animal models of aganglionosis have contributed greatly to our understanding of the genetic basis of HSCR. Several natural or target mutations in specific genes have been reported to produce developmental defects in neural crest migration, differentiation or survival. The aim of this study was to review the currently available knockout models of HSCR to better understand the molecular basis of HSCR.

METHODS

A review of the literature using the keywords "Hirschsprung's disease", "aganglionosis", "megacolon" and "knockout mice model" was performed. Resulting publications were reviewed for relevant mouse models of human aganglionosis. Reference lists were screened for additional relevant studies.

RESULTS

16 gene knockout mouse models were identified as relevant rodent models of human HSCR. Due to the deletion of a specific gene, the phenotypes of these knockout models are diverse and range from small bowel dilatation and muscular hypertrophy to total intestinal aganglionosis.

CONCLUSIONS

Mouse models of aganglionosis have been instrumental in the discovery of the causative genes of HSCR. Although important advances have been made in understanding the genetic basis of HSCR, animal models of aganglionosis in future should further help to identify the unknown susceptibility genes in HSCR.

Syndromic Hirschsprung's disease and associated congenital heart disease: a systematic review

PURPOSE

Hirschsprung's disease (HD) occurs as an isolated phenotype in 70% of infants and is associated with additional congenital anomalies or syndromes in approximately 30% of patients. The cardiac development depends on neural crest cell proliferation and is closely related to the formation of the enteric nervous system. HD associated with congenital heart disease (CHD) has been reported in 5-8% of cases, with septation defects being the most frequently recorded abnormalities. However, the prevalence of HD associated with CHD in infants with syndromic disorders is not well documented. This systematic review was designed to determine the prevalence of CHD in syndromic HD.

METHODS

A systematic review of the literature using the keywords "Hirschsprung's disease", "aganglionosis", "congenital megacolon", "congenital heart disease" and "congenital heart defect" was performed. Resulting publications were reviewed for epidemiology and morbidity. Reference lists were screened for additional relevant studies.

RESULTS

A total of fifty-two publications from 1963 to 2014 reported data on infants with HD associated with CHD. The overall reported prevalence of HD associated with CHD in infants without chromosomal disorders was 3%. In infants with syndromic disorders, the overall prevalence of HD associated with CHD ranged from 20 to 80 % (overall prevalence 51%). Septation defects were recorded in 57% (atrial septal defects in 29%, ventricular septal defects in 32%), a patent ductus arteriosus in 39%, vascular abnormalities in 16%, valvular heart defects in 4% and Tetralogy of Fallot in 7%.

CONCLUSION

The prevalence of HD associated with CHD is much higher in infants with chromosomal disorders compared to infants without associated syndromes. A routine echocardiogram should be performed in all infants with syndromic HD to exclude cardiac abnormalities.