Down syndrome and the enteric nervous system

Respiratory and airway disorders in children with Down Syndrome: a review of the clinical challenges and management

Down Syndrome (DS), or Trisomy 21, is a common inherited chromosomal disorder, caused by an extra copy of chromosome 21, with features including intellectual disability, hearing and vision disorders, hypotonia, hypothyroidism, cardiac and gastrointestinal structural abnormalities. The characteristic features of flattened nasal bridge, mandibular and maxillary hypoplasia, relative macroglossia, and a narrow nasopharyngeal region all predispose to airway complications and structural abnormalities can extend to the lower airways and lung parenchyma. Congenital airway stenoses and malacia are present in around 1.5% children with DS and in 20% of these, there are multiple anomalies. Structural lung abnormalities include reduced alveolar numbers and altered lung architecture. The prevalence of pulmonary hypertension is a significantly increased, estimated to affect 5-10%, and increases if congenital or gastrointestinal co-morbidities are also present. The association of DS with hypotonia, increased oral secretions, gastrointestinal reflux and aspiration and obesity increase the morbidity associated with these anatomical variants contributing to poor airway clearance and increased risk of respiratory tract infections. In addition, it is been recognised that the increased risk of infections (particularly of the respiratory tract) as well as autoimmune disorders and haematological malignancies suggest a level of immunodeficiency and immune dysregulation. The anatomical features of DS predispose children to the development of sleep disordered breathing (SDB) in addition to adenotonsillar hypertrophy, the primary cause in children. Treatment options include surgery, non-invasive ventilation, and anti-inflammatory medications. Emerging techniques include drug-induced sleep endoscopy (DISE), a useful tool for assessment of the upper airway in children with OSA and to identify the additional sites of airway obstruction that may be present in DS and hypoglossal nerve stimulation for individuals resistant other treatments.

Microbiota and social behavior alterations in a mouse model of down syndrome: Modulation by a synbiotic treatment

Sex differences in the composition and functionality of gut microbiota are an emerging field of interest in neurodevelopmental disorders, as they may help in understanding the phenotypic disparities between males and females. This study aimed to characterize sex-related specific alterations in gut microbiota composition in a mouse model of Down syndrome (Ts65Dn mice, TS mice) through the sequencing of the PCR-amplified 16S ribosomal DNA fraction. Moreover, it intended to examine whether the modulation of gut microbiota by the administration of a synbiotic (SYN) treatment would be beneficial for the behavioral alterations observed in male and female TS mice. Our results show that male, but not female, TS mice exhibit alterations in beta diversity compared to their wild-type (WT) littermates. Sex-dependent differences are also observed in the relative abundance of the classes Bacilli and Clostridia. Administering the SYN effectively counteracts hypersociability in females, and normalizes the overall abundance of Bacilli, specifically by increasing Lactobacillaceae. On the contrary, it rescues emotional recognition deficits in male TS mice and increases the relative abundance of the families Lactobacillaceae, Streptococcaceae and Atopobiaceae. In addition, a metagenome KEGG analysis of differentially enriched pathways shows relevant changes in the cofactor biosynthesis and the amino acid synthesis categories. Finally, following SYN treatment, both male and female TS mice exhibit a robust increase in propionic acid levels compared to WT littermates. These findings suggest sex-specific mechanisms that could link gut microbiota composition with behavior in TS mice, and underscore the potential of targeted gut microbiota interventions to modulate social abnormalities in neurodevelopmental disorders.

Trisomy 21 and Congenital Heart Disease: Impact on Health and Functional Outcomes From Birth Through Adolescence: A Scientific Statement From the American Heart Association

Due to improvements in recognition and management of their multisystem disease, the long-term survival of infants, children, and adolescents with trisomy 21 and congenital heart disease now matches children with congenital heart disease and no genetic condition in many scenarios. Although this improved survival is a triumph, individuals with trisomy 21 and congenital heart disease have unique and complex care needs in the domains of physical, developmental, and psychosocial health, which affect functional status and quality of life. Pulmonary hypertension and single ventricle heart disease are 2 known cardiovascular conditions that reduce life expectancy in individuals with trisomy 21. Multisystem involvement with respiratory, endocrine, gastrointestinal, hematological, neurological, and sensory systems can interact with cardiovascular health concerns to amplify adverse effects. Neurodevelopmental, psychological, and functional challenges can also affect quality of life. A highly coordinated interdisciplinary care team model, or medical home, can help address these complex and interactive conditions from infancy through the transition to adult care settings. The purpose of this Scientific Statement is to identify ongoing cardiovascular and multisystem, developmental, and psychosocial health concerns for children with trisomy 21 and congenital heart disease from birth through adolescence and to provide a framework for monitoring and management to optimize quality of life and functional status.

The role of Down syndrome cell adhesion molecule in Down syndrome

Down syndrome (DS) is caused by the presence of an extra copy of the entire or a portion of human chromosome 21 (HSA21). This genomic alteration leads to elevated expression of numerous HSA21 genes, resulting in a variety of health issues in individuals with DS. Among the genes located in the DS "critical region" of HSA21, Down syndrome cell adhesion molecule (DSCAM) plays an important role in neuronal development. There is a growing body of evidence underscoring DSCAM's involvement in various DS-related disorders. This review aims to provide a concise overview of the established functions of DSCAM, with a particular focus on its implications in DS. We delve into the roles that DSCAM plays in DS-associated diseases. In the concluding section of this review, we explore prospective avenues for future research to further unravel DSCAM's role in DS and opportunities for therapeutic treatments.

Comprehensive Manometric Evaluation of Dysphagia in Patients with Down Syndrome

Dysphagia is a common symptom in children with Down syndrome and is conventionally evaluated with imaging and endoscopy; high-resolution manometry is not routinely utilized. The aim of this study was to describe and correlate pharyngeal and esophageal manometry findings with contrast studies and endoscopy in patients with Down syndrome and dysphagia. Electronic medical records of patients with Down syndrome with dysphagia seen at our center between January 2008 and January 2022 were reviewed. Data collected included demographics, co-morbidities, symptoms, imaging, endoscopy, and manometry. Twenty-four patients with Down syndrome [median age of 14.9 years (IQR 7.6, 20.5), 20.8% female] met inclusion criteria. Common presenting symptoms of dysphagia included vomiting or regurgitation in 15 (62.5%) patients, and choking, gagging, or retching in 10 (41.7%) patients. Esophageal manometry was abnormal in 18/22 (81.2%) patients. The most common findings were ineffective esophageal motility in 9 (40.9%) followed by esophageal aperistalsis in 8 (36.4%) patients. Rumination pattern was noted in 5 (22.8%) patients. All 6 (25%) patients who previously had fundoplication had esophageal dysmotility. Strong agreement was noted between upper gastrointestinal studies and high-resolution esophageal manometry (p = 1.0) but no agreement was found between pharyngeal manometry and video fluoroscopic swallow studies (p = 0.041). High-resolution pharyngeal and esophageal manometry provide complementary objective data that may be critical in tailoring therapeutic strategies for managing patients with Down syndrome with dysphagia.

Disorders of Gut-Brain Interaction in a National Cohort of Children With Down Syndrome

Background/Aims

Disorders of brain-gut interaction (DGBIs) are present in adults and children around the world. Down syndrome (DS) is the most common chromosomal condition in humans. While DS has associations with many organic medical conditions, the frequency of DGBIs in children and adolescents with DS has not previously been studied. We assess the rate of DGBIs in children and adolescents 4-18 years of age with DS in the United States using the Rome IV criteria by caregiver report.

Methods

This is a cross-sectional national survey study in which caregivers (n = 114) of children with DS completed an online survey about their child's gastrointestinal symptoms and quality of life (QoL).

Results

Using the Rome IV parent-report diagnostic questionnaire, 51.8% of children met symptom-based criteria for at least 1 DGBI. Functional constipation (36.0%) and irritable bowel syndrome (14.9%) were the most common disorders identified. QoL was lower in children with at least 1 disorder as compared to children who did not meet criteria for any disorders (mean QoL = 62.3 vs mean QoL = 72.9, P < 0.001). Almost all children with DS and concomitant autism (87.5%) had at least 1 DGBI.

Conclusions

DGBIs are common in children with DS and are associated with diminished QoL.

Prevalence of Hirschsprung-associated enterocolitis in patients with Hirschsprung disease

PURPOSE

Hirschsprung's associated enterocolitis (HAEC) is a complication of Hirschsprung's Disease (HD) with considerable morbidity and mortality. The variability in presentation leads to a wide variety of the reported prevalence pre-and postoperatively. This systematic review aimed to clarify the prevalence of HAEC in short-(S-HD), long (L-HD), TCA and the type of operation used.

METHODS

A systematic literature-based search for relevant cohorts was performed using Pubmed/Medline, Cochrane Library from its inception to May 2021. Studies reporting on pre-and postoperative enterocolitis, segment length, and surgical procedure (Soave, Swenson, Duhamel) were included. Pooled prevalence and subgroup analysis have been calculated for pre-and postoperative HAEC.

RESULTS

4738 articles were identified from the literature search, among which 57 studies, including 9744 preoperative and 8568 postoperative patients, were included. The groups were sorted by length of the aganglionic segment for further analysis. The pooled prevalence for preoperative HAEC was 18.3% for all types, 15.2% for S-HD and 26.1% for TCA. The pooled prevalence for postoperative HAEC was in total 18.2% for all segment lengths and used techniques. Subgroup analysis showed no significant difference in the occurrence of postoperative enterocolitis between the three techniques.

CONCLUSION

The prevalence of preoperative HAEC increases with segment length. However, pooled data suggest that the postoperative risk for developing HAEC, independently of the employed method and segment length, is comparable to the preoperative risk.

Contemporary management of Hirschsprung disease in New Zealand

BACKGROUND

The aim of this study was to report the contemporary management of Hirschsprung disease (HD) in New Zealand.

METHODS

We undertook a national multi-centre retrospective review of all newly diagnosed cases of HD during a 16-year period (2000-2015). Demographics, genetic and syndromic associations, family history, radiology and histology results and surgical interventions were analysed.

RESULTS

A total of 246 cases (males:females 4:1) were identified, an incidence of 1:3870 live births. Short-segment disease was present in 81.7%, long-segment disease in 8.5%, total colonic aganglionosis in 6.5% and unknown in 3.3%. HD was diagnosed by 4 weeks' corrected gestational age in 67%. Thirty cases (12%) also had Trisomy 21. Fifty-three (21.5%) patients required a repeat rectal biopsy for definitive diagnosis. A contrast enema was performed in 55% and identified the transition zone with 69% accuracy. Primary pull-through surgery was undertaken in 59% (65% of short-segment cases) at a median age of 27 days; others were initially managed by a defunctioning stoma. The commonest definitive procedure was a Soave-Boley endorectal pull-through (79%) (or similar variant). During a median follow-up of 7.4 years, six (2.5%) survivors underwent a redo pull-through, 13 (5.5%) an appendicostomy, 16 (6.8%) a defunctioning stoma and 10 never had a definitive procedure. Total colonic aganglionosis was significantly more likely to be fatal (12.5% versus 0.5%, P < 0.0005) or associated with a permanent end stoma (27.5% versus 4.5%, P < 0.0005).

CONCLUSIONS

Most New Zealand born infants with short-segment HD are currently managed by primary pull-through, usually in the first months of life.

Multiorgan involvement and management in children with Down syndrome

AIM

To review multiorgan involvement and management in children with Down syndrome (DS).

METHODS

A literature review of articles from 1980 to 2019 using the MEDLINE interface of PubMed was performed using the following search terms- [Down syndrome] or [Trisomy 21] AND [Cardiology] or [Respiratory] or [neurodevelopment] or [epilepsy] or [musculoskeletal] or [immune system] or [haematological] or [endocrine] or [gastrointestinal] or [ophthalmological] or [Ear Nose Throat] or [dermatology] or [renal].

RESULTS

Congenital heart disease particularly septal defects occur in over 60% of infants with DS and 5%-34% of infants develop persistent pulmonary hypertension of the newborn irrespective of a diagnosis of congenital heart disease. Early recognition and management of aspiration, obstructive sleep apnoea and recurrent lower respiratory tract infections (LRTI) could reduce risk of developing pulmonary hypertension in later childhood. Children with DS have an increased risk of autistic spectrum disorder, attention deficit disorder and epilepsy particularly infantile spasms, which are associated with poor neurodevelopmental outcomes. Congenital anomalies of the gastrointestinal and renal system as well as autoimmune diseases, coeliac disease, arthropathy, thyroid dysfunction fold diabetes mellitus and dermatological conditions are more common. Hearing and visual anomalies are also well recognised association with DS (Table 1).

CONCLUSION

Children with DS are at an increased risk of multiorgan comorbidities. Organ-specific health surveillance may provide holistic care for the children and families with DS throughout childhood.

Hirschsprung disease and Down syndrome: From the reappraisal of risk factors to the impact of surgery

INTRODUCTION

The association of Hirschsprung disease (HSCR) and Down Syndrome (DS) is not uncommon (HSCR+DS). This paper aims at reporting the results of a 24-year series focusing on surgical approach, complications and long term outcome.

MATERIALS AND METHODS

The notes of all patients admitted with a diagnosis of HSCR+DS have been retrospectively reviewed. Surgical details, intraoperative complications, long term issues and functional outcome have been recorded. The results have been compared to those of patients without DS and were assessed based on surgical approach.

RESULTS

A total of 23 HSCR+DS out of a series of 385 HSCR (6%) have been included. Preoperative enterocolitis (HAEC) was reported by 32%. Associated anomalies were detected in more than half of the patients. In particular, Congenital Heart Defects (CHDs) were reported by 57%. Postoperative complications (mostly symptomatic anal sphincter achalasia) were experienced by 55%. Constipation was experienced by 30%; severe continence issues, by 53%. One patient suffering from severe CHDs died. With regard to complications, only symptomatic anal achalasia requiring intrasphincteric BoTox injection was significantly more frequent in HSCR+DS (30% vs 10%, p = 0.0071). Similarly, continence proved to be significantly worse in HSCR+DS.

DISCUSSION

With the exception of symptomatic anal achalasia, HSCR+DS patients proved not to have a higher likelihood of complications compared to HSCR alone. On the other hand, functional results in the long term are worse. As a consequence, long term follow up and personalized rehabilitation programs are warranted for this delicate subset of HSCR patients.

LEVEL OF EVIDENCE

Level III.

Gastrointestinal disorders in Down syndrome

Down syndrome is the most common human chromosomal disorder. Among clinical findings, one constant concern is the high prevalence of gastrointestinal system alterations. The aim of this study was to determine the prevalence of gastrointestinal disorders at a Down syndrome outpatient clinic during a 10-year follow-up period. Data from medical files were retrospectively reviewed from 1,207 patients. Gastrointestinal changes occurred in 612 (50.7%). The most prevalent disorder was chronic intestinal constipation. Intestinal parasite occurred in 22% (mainly giardiasis), gastroesophageal reflux disease in 14%, digestive tract malformations occurred in 5%: 13 cases of duodenal atresia, 8 of imperforate anus, 4 annular pancreases, 2 congenital megacolon, 2 esophageal atresias, 2 esophageal compression by anomalous subclavian and 1 case of duodenal membrane. We had 38/1,207 (3.1%) patients with difficulty in sucking and only three with dysphagia that resolved before the second year of life. Peptic ulcer disease, celiac disease, and biliary lithiasis were less prevalent with 3% each. Awareness of the high prevalence of gastrointestinal disorders promotes outstanding clinical follow-up as well as adequate development and greater quality of life for patients with Down syndrome and their families.

Down syndrome mouse models have an abnormal enteric nervous system

Children with trisomy 21 (Down syndrome [DS]) have a 130-fold increased incidence of Hirschsprung Disease (HSCR), a developmental defect where the enteric nervous system (ENS) is missing from distal bowel (i.e., distal bowel is aganglionic). Treatment for HSCR is surgical resection of aganglionic bowel, but many children have bowel problems after surgery. Post-surgical problems like enterocolitis and soiling are especially common in children with DS. To determine how trisomy 21 affects ENS development, we evaluated the ENS in two DS mouse models, Ts65Dn and Tc1. These mice are trisomic for many chromosome 21 homologous genes, including Dscam and Dyrk1a, which are hypothesized to contribute to HSCR risk. Ts65Dn and Tc1 mice have normal ENS precursor migration at E12.5 and almost normal myenteric plexus structure as adults. However, Ts65Dn and Tc1 mice have markedly reduced submucosal plexus neuron density throughout the bowel. Surprisingly, the submucosal neuron defect in Ts65Dn mice is not due to excess Dscam or Dyrk1a, since normalizing copy number for these genes does not rescue the defect. These findings suggest the possibility that the high frequency of bowel problems in children with DS and HSCR may occur because of additional unrecognized problems with ENS structure.

Early impacts of modified food consistency on oromotor outcomes in mouse models of Down syndrome

Down syndrome (DS) in humans is associated with differences of the central nervous system and oromotor development. DS also increases risks for pediatric feeding challenges, which sometimes involve the use of altered food consistencies. Therefore, experimental food consistency paradigms are of interest to oromotor investigations in mouse models of Down syndrome (DS). The present work reports impacts of an altered food consistency paradigm on the Ts65Dn and Dp(16)1Yey mouse models of DS, and sibling control mice. At weaning, Ts65Dn, Dp(16)1Yey and respective controls were assigned to receive either a hard food or a soft food (eight experimental groups, n = 8-10 per group). Two weeks later, mice were assessed for mastication speeds and then euthanized for muscle analysis. Soft food conditions were associated with significantly smaller weight gain (p = .003), significantly less volitional water intake through licking (p = .0001), and significant reductions in size of anterior digastric myofibers positive for myosin heavy chain isoform (MyHC) 2b (p = .049). Genotype was associated with significant differences in weight gain (p = .004), significant differences in mastication rate (p = .001), significant differences in a measure of anterior digastric muscle size (p = .03), and significant reductions in size of anterior digastric myofibers positive for MyHC 2a (p = .04). In multiple measures, the Ts65Dn model of DS was more affected than other genotype groups. Findings indicate a soft food consistency condition in mice is associated with significant reductions in weight gain and oromotor activity, and may impact digastric muscle. This suggests extended periods of food consistency modifications may have impacts that extend beyond their immediate roles in facilitating deglutition.

The evaluation and management of respiratory disease in children with Down syndrome (DS)

Children with Down syndrome (DS) have wide range of respiratory problems. Although underlying abnormalities in the respiratory system are important causes of morbidity and mortality in children with DS, particularly in the young, abnormalities in other organ systems may also impact respiratory function. A comprehensive evaluation of the child with DS and respiratory disease may prevent short-term morbidity and mortality, and reduce the incidence of complications in the long term. This review provides an overview of the various causes of respiratory disease, and insight into some of the newer therapies available to treat obstructive sleep apnea, in this population.

Chromosome-wise Protein Interaction Patterns and Their Impact on Functional Implications of Large-Scale Genomic Aberrations

Gene copy-number changes influence phenotypes through gene-dosage alteration and subsequent changes of protein complex stoichiometry. Human trisomies where gene copy numbers are increased uniformly over entire chromosomes provide generic cases for studying these relationships. In most trisomies, gene and protein level alterations have fatal consequences. We used genome-wide protein-protein interaction data to identify chromosome-specific patterns of protein interactions. We found that some chromosomes encode proteins that interact infrequently with each other, chromosome 21 in particular. We combined the protein interaction data with transcriptome data from human brain tissue to investigate how this pattern of global interactions may affect cellular function. We identified highly connected proteins that also had coordinated gene expression. These proteins were associated with important neurological functions affecting the characteristic phenotypes for Down syndrome and have previously been validated in mouse knockout experiments. Our approach is general and applicable to other gene-dosage changes, such as arm-level amplifications in cancer.

Achalasia: Outcome in children

BACKGROUND

Oesophageal achalasia is well-recognized but relatively rare in children, occasionally appearing as the "triple A" syndrome (with adrenal insufficiency and alacrima). Treatment modalities, as in adult practice, are not curative, often needing further interventions and spurring the search for better management. The outcome for syndromic variants is unknown. We sought to define the efficacy of treatments for children with achalasia with and without triple A syndrome.

METHODS

We conducted a retrospective analysis of presentation and outcomes for 42 children with achalasia presenting over three decades to a major pediatric referral center. Long term impact of the diagnosis was assessed by questionnaire.

RESULTS

We identified 42 children including six with triple A syndrome. The median overall age at diagnosis was 10.8 years and median follow-up 1593 days. Initial Heller myotomy in 17 required further interventions in 11 (65%), while initial treatment with botulinum toxin (n = 20) was ultimately followed by myotomy in 17 (85%). Ten out of 35 patients who underwent myotomy required a repeat myotomy (29%). Patients with triple A syndrome developed symptoms earlier, but had delayed diagnosis, were more underweight at diagnosis and at last follow up. Questionnaire results suggested a significant long term deleterious impact on the quality of life of children and their families.

CONCLUSION

Many children with achalasia relapse after initial treatment, undergoing multiple, different procedures, despite which symptoms persist and impact on quality of life. Symptoms develop earlier in patients with triple A syndrome, but the diagnosis is delayed and this has substantial nutritional impact.

Detailed assessment of incontinence in boys with fragile-X-syndrome in a home setting

Fragile-X-syndrome (FXS) is caused by a mutation on the X chromosome (Xq27.3). Males with a full mutation have typical dysmorphic signs, moderate intellectual disability and psychological disorders. Twenty-five to fifty percent are affected by incontinence. The aim of the study was to assess subtypes of incontinence and psychological problems in children with FXS in their home environments. Twenty-two boys with FXS (mean age 11.0 years) and 22 healthy controls (mean age 11.1 years) were examined with sonography, uroflowmetry, 48-h bladder diary, physical examination, IQ test, parental psychiatric interview and questionnaires regarding incontinence and psychological symptoms in a home setting. Boys with FXS had higher rates of incontinence than controls (59.1 vs. 4.8 %). The most common subtypes in FXS boys were primary non-monosymptomatic nocturnal enuresis, urge incontinence and nonretentive faecal incontinence. 90.9 % boys with FXS had a psychological comorbidity. Incontinence and behavioural symptoms were not associated.

CONCLUSION

Boys with FXS have a higher risk for physical disabilities, psychological disorders and incontinence than healthy boys. Constipation is not a major problem in FXS. As effective treatment is available for children with ID, we recommend offering assessment and therapy to all children with FXS and incontinence.

WHAT IS KNOWN

• Boys with fragile-X-syndrome (FXS) have higher rates of incontinence, psychological disorders and somatic conditions than typically developing boys. What is New: • Constipation is a rare condition in FXS in contrast to other genetic syndromes. • Although incontinence rates are higher, urological findings (uroflowmetry, sonography) are not more pathological per se in FXS.

Pulmonary Crohn's Disease in Down Syndrome: A Link or Linkage Problem

Crohn's disease (CD) is an autoimmune inflammatory disorder that primarily affects the gastrointestinal tract. It may have pulmonary involvement, which has been rarely reported in pediatric patients. Down syndrome (DS) has been associated with increased frequency of autoimmune diseases. However, associations between CD and DS have been rarely reported. We present the case of a 5-year-old girl with known DS and a history of chronic intermittent abdominal pain who presented with persistent pneumonia. Her workup included a chest computed tomography (CT) scan that showed multiple noncalcified pulmonary nodules. An extensive infectious workup was done that was negative. CT-guided needle biopsy of the lung nodules showed necrotizing granulomas. This raised concern for primary CD with extraintestinal pulmonary manifestation. An esophagogastroduodenoscopy and colonoscopy were performed, and colon biopsies showed scattered epithelioid granulomas. Based on this information, there was consensus that her lung nodules were secondary to CD. She was started on standard therapy for CD, and her abdominal and respiratory symptoms gradually improved. However, she continues to have mild residual lung calcification and fibrosis. To our knowledge, this is the first reported case of pulmonary CD in a child with DS. The natural history of pulmonary CD in the pediatric population is not very well studied. Furthermore, since DS has been well known to be associated with increased frequency of malignancies and autoimmune conditions due to immune dysregulation, it is difficult to predict the severity and possible complications in this patient.

Calretinin-Immunoreactive Hypoinnervation in Down Syndrome (DS): Report of an Infant with Very Short-Segment Hirschsprung Disease and Comparison to Biopsy Findings in 20 Normal Infants and 11 Infants with DS and Chronic Constipation

In Down syndrome (DS) constipation is common, and the incidence of Hirschsprung disease (HD) is 1-2%. Rectal suction biopsies (RSBs) in DS may show discordant features; calretinin immunoreactivity (CRir) often helps resolve discrepancies. We report a case of unequivocal very short-segment HD (vsHD) in an infant with DS who had aganglionosis with abnormal acetylcholine esterase (AChE) activity in 3 RSBs. The CRir patterns were scanty positive rather than the expected absent CRir innervation in the lamina propria (LP). The resection specimen was grossly typical for short-segment HD, with a 5.5-cm, narrow but normally ganglionated segment proximal to the verified very short distal anganglionic zone. Unequivocal calretinin hypoinnervation was limited to the distal 2 cm, substantiating the warning of Kapur that small numbers of CRir nerves in the LP do not exclude a diagnosis of vsHD. We evaluated RSBs from 11 DS and 20 randomly selected normal infants <6 months of age with chronic constipation. The normal infants had abundant mucosal calretinin innervation and AChE histochemistry. We observed variable CRir hypoinnervation in RSBs in DS infants (including 6/7 with "normal" original diagnosis and 1/4 with HD). Our findings caution against overdependence on "normal" calretinin immunohistochemistry and suggest that AChE may be more reliable than CRir in the context of DS. An unknown number of patients with DS may have enteric nervous system disorders functionally similar to HD, which are possibly related to abnormal or imbalanced autonomic innervation, of which distal calretinin hypoinnervation is one manifestation, despite the presence of ganglia.

Achalasia and Down syndrome: a unique association not to be missed

Achalasia is a rare primary oesophageal motility disorder that presents as a functional obstruction at the oesophago-gastric junction. The prevalence of achalasia in Down syndrome is much higher, which implies a unique association between these two uncommon conditions. Although the exact aetiology of achalasia is unknown, studies have proposed that its pathogenesis is related to autoimmune, infectious or genetic factors, leading to the intrinsic loss of inhibitory myenteric neurons in both the oesophagus and lower oesophageal sphincter. We herein report the case of a 16-month-old girl with Down syndrome and achalasia who was initially treated for gastro-oesophageal reflux disease. The diagnosis of achalasia was made only when her condition deteriorated, with subsequent failure to thrive, and upon further investigations, including barium swallow study and upper endoscopy. We also review the various mechanisms postulated in the development of achalasia in Down syndrome, as well as the various treatment modalities available for this rare disorder.

Immunosuppressant dose reduction and long-term rejection risk in renal transplant recipients with severe bacterial pneumonia

INTRODUCTION

Due to lifelong immunosuppression, renal transplant recipients (RTRs) are at risk of infectious complications such as pneumonia. Severe pneumonia results in respiratory failure and is life‑threatening. We aimed to examine the influence of immunosuppressant dose reduction on RTRs with bacterial pneumonia and respiratory failure.

METHODS

From January 2001 to January 2011, 33 of 1,146 RTRs at a single centre developed bacterial pneumonia with respiratory failure. All patients were treated using mechanical ventilation and aggressive therapies in the intensive care unit.

RESULTS

Average time from kidney transplantation to pneumonia with respiratory failure was 6.8 years. In-hospital mortality rate was 45.5% despite intensive care and aggressive therapies. Logistic regression analysis indicated that a high serum creatinine level at the time of admission to the intensive care unit (odds ratio 1.77 per mg/dL, 95% confidence interval 1.01-3.09; p = 0.045) was a mortality determinant. Out of the 33 patients, immunosuppressive agents were reduced in 17 (51.5%). We found that although immunosuppressant dose reduction tended to improve in-hospital mortality, this was not statistically significant. Nevertheless, during a mean follow-up period of two years, none of the survivors (n = 18) developed acute rejection or allograft necrosis.

CONCLUSION

In RTRs with bacterial pneumonia and respiratory failure, higher serum creatinine levels were a mortality determinant. Although temporary immunosuppressant dose reduction might not reduce mortality, it was associated with a minimal risk of acute rejection during the two-year follow-up. Our results suggest that early immunosuppressant reduction in RTRs with severe pneumonia of indeterminate microbiology may be safe even when pathogens are bacterial in nature.

Idiopathic (primary) achalasia: a review

Idiopathic achalasia is a primary esophageal motor disorder characterized by loss of esophageal peristalsis and insufficient lower esophageal sphincter relaxation in response to deglutition. Patients with achalasia commonly complain of dysphagia to solids and liquids, bland regurgitation often unresponsive to an adequate trial of proton pump inhibitor, and chest pain. Weight loss is present in many, but not all patients. Although the precise etiology is unknown, it is often thought to be either autoimmune, viral immune, or neurodegenerative. The diagnosis is based on history of the disease, barium esophagogram, and esophageal motility testing. Endoscopic assessment of the gastroesophageal junction and gastric cardia is necessary to rule out malignancy. Newer diagnostic modalities such as high resolution manometry help in predicting treatment response in achalasia based on esophageal pressure topography patterns identifying three phenotypes of achalasia (I-III) and outcome studies suggest better treatment response with types I and II compared to type III. Although achalasia cannot be permanently cured, excellent outcomes are achieved in over 90 % of patients. Current medical and surgical therapeutic options (pneumatic dilation, endoscopic and surgical myotomy, and pharmacologic agents) aim at reducing the LES pressure and facilitating esophageal emptying by gravity and hydrostatic pressure of retained food and liquids. Either graded pneumatic dilatation or laparoscopic surgical myotomy with a partial fundoplication are recommended as initial therapy guided by patient age, gender, preference, and local institutional expertise. The prognosis in achalasia patients is excellent. Most patients who are appropriately treated have a normal life expectancy but the disease does recur and the patient may need intermittent treatment.

Dimensions of central incisors, canines, and first molars in subjects with Down syndrome measured on cone-beam computed tomographs

INTRODUCTION

The literature on tooth dimensions in subjects with Down syndrome (DS) is scarce. To our knowledge, no studies have yet been published in which the morphometry of the teeth in DS subjects has been determined using computed tomography.

METHODS

The study group consisted of 40 subjects with DS, aged 10 to 40 years. An age- and sex-matched control group was selected. Cone-beam computed tomography images were retrieved from the archive of the Santiago de Compostela University in Spain. The maxillary central incisors, canines, and first molars were evaluated. The following variables were analyzed: overall tooth length, crown height, root length, mesiodistal diameter, vestibular-palatine diameter, crown-to-root ratio, and cervical circumference.

RESULTS

The teeth of subjects with DS were smaller than those of the controls, although the crown-to-root ratio was maintained. No clear sexual dimorphism was detected, but the root lengths of the incisors were greater in male subjects. Crown height, mesiodistal diameter, and crown-to-root ratio showed progressive reductions with age. There appeared to be a degree of "fluctuating dental asymmetry" with respect to vestibular-palatine diameter and cervical circumference.

CONCLUSIONS

Our findings confirm microdontia of the permanent teeth and progressive reductions in tooth sizes with age in persons with DS. These variations might be relevant to orthodontic treatment planning.

Family case of achalasia cardia: Case report and review of literature

Achalasia cardia is an idiopathic disease that occurs as a result of inflammation and degeneration of myenteric plexi leading to the loss of postganglionic inhibitory neurons required for relaxation of the lower esophageal sphincter and peristalsis of the esophagus. The main symptoms of achalasia are dysphagia, regurgitation, chest pain and weight loss. At present, there are three main hypotheses regarding etiology of achalasia cardia which are under consideration, these are genetic, infectious and autoimmune. Genetic theory is one of the most widely discussed. Case report given below represents an inheritable case of achalasia cardia which was not diagnosed for a long time in an 81-year-old woman and her 58-year-old daughter.

Hirschsprung's disease associated with Down syndrome: a meta-analysis of incidence, functional outcomes and mortality

PURPOSE

Down syndrome (DS) is the most frequent chromosomal abnormality associated with Hirschsprung's disease (HD). It has often been suggested that this association results in poorer outcomes with regard to postoperative complications, continence and mortality. On the other hand, the results after surgical treatment of HD in patients with DS are reportedly similar to those in cases with HD alone. The objective of this study was to determine the incidence of DS in cohorts with HD, and to compare pre-/postoperative complications, functional outcome and mortality between cohorts with and without coexisting DS.

METHODS

A systematic literature-based search for relevant cohorts was conducted using multiple online databases. The number of DS cases in HD cohorts was recorded and data on pre-/postoperative complications, functional outcome and mortality were extracted. Pooled odds ratios with 95% confidence intervals were calculated using meta-analysis methodology.

RESULTS

Sixty-one articles met defined inclusion criteria, comprising data from 16,497 patients with HD. The overall incidence of DS among them was 7.32%. Vice versa, the incidence of HD in 29,418 patients with DS was 2.62%. There were no significant differences regarding the male-to-female ratio between cohorts with and without coexisting DS (4:1 vs. 3:1 respectively; P = 0.5376). The rate of additional comorbidities was significantly higher in HD associated with DS (P < 0.0001). Recto-sigmoid HD was in both cohorts the most common type of HD (P = 0.8231). Long-segment HD was significantly more frequent in HD with coexisting DS (P = 0.0267), while total colonic aganglionosis occurred significantly more often in HD without DS (P = 0.0003). There were no significant differences in preoperative constipation/obstruction (P = 0.5967), but the rate of preoperative enterocolitis was significantly higher in HD associated with DS (P = 0.0486). Postoperative complications such as recurrent enterocolitis (P = 0.0112) and soiling (P = 0.0002) were significantly more frequent in HD with coexisting DS. Although not statistically significant, fecal incontinence (P = 0.1014) and persistent constipation (P = 0.1670) occurred more often after surgical treatment of HD with DS. The mortality rate was significantly higher in HD associated with DS (P < 0.0001).

CONCLUSIONS

The association of HD with DS is well-recognized with an incidence of 7.32%. A large number of patients with DS continue to have persistent bowel dysfunction after surgical treatment of HD. Our data provide strong evidence that the coexistence of HD and DS is associated with higher rates of pre-/postoperative enterocolitis, poorer functional outcomes and increased mortality.

Infantile hypertrophic pyloric stenosis--genetics and syndromes

Infantile hypertrophic pyloric stenosis (IHPS) is a common condition in neonates that is characterized by an acquired narrowing of the pylorus. The aetiology of isolated IHPS is still largely unknown. Classic genetic studies have demonstrated an increased risk in families of affected infants. Several genetic studies in groups of individuals with isolated IHPS have identified chromosomal regions linked to the condition; however, these associations could usually not be confirmed in subsequent cohorts, suggesting considerable genetic heterogeneity. IHPS is associated with many clinical syndromes that have known causative mutations. Patients with syndromes associated with IHPS can be considered as having an extreme phenotype of IHPS and studying these patients will be instrumental in finding causes of isolated IHPS. Possible pathways in syndromic IHPS include: (neuro)muscular disorders; connective tissue disorders; metabolic disorders; intracellular signalling pathway disturbances; intercellular communication disturbances; ciliopathies; DNA-repair disturbances; transcription regulation disorders; MAPK-pathway disturbances; lymphatic abnormalities; and environmental factors. Future research should focus on linkage analysis and next-generation molecular techniques in well-defined families with multiple affected members. Studies will have an increased chance of success if detailed phenotyping is applied and if knowledge about the various possible causative pathways is used in evaluating results.

Chromosomal and related Mendelian syndromes associated with Hirschsprung's disease

Hirschsprung's disease (HSCR) is a fairly frequent cause of intestinal obstruction in children. It is characterized as a sex-linked heterogonous disorder with variable severity and incomplete penetrance giving rise to a variable pattern of inheritance. Although Hirschsprung's disease occurs as an isolated phenotype in at least 70% of cases, it is not infrequently associated with a number of congenital abnormalities and associated syndromes, demonstrating a spectrum of congenital anomalies. Certain of these syndromic phenotypes have been linked to distinct genetic sites, indicating underlying genetic associations of the disease and probable gene-gene interaction, in its pathogenesis. These associations with HSCR include Down's syndrome and other chromosomal anomalies, Waardenburg syndrome and other Dominant sensorineural deafness, the Congenital Central Hypoventilation and Mowat-Wilson and other brain-related syndromes, as well as the MEN2 and other tumour associations. A number of other autosomal recessive syndromes include the Shah-Waardenburg, the Bardet-Biedl and Cartilage-hair hypoplasia, Goldberg-Shprintzen syndromes and other syndromes related to cholesterol and fat metabolism among others. The genetics of Hirschsprung's disease are highly complex with the majority of known genetic sites relating to the main susceptibility pathways (RET an EDNRB). Non-syndromic non-familial, short-segment HSCR appears to represent a non-Mendelian condition with variable expression and sex-dependent penetrance. Syndromic and familial forms, on the other hand, have complex patterns of inheritance and being reported as autosomal dominant, recessive and polygenic patterns of inheritance. The phenotypic variability and incomplete penetrance observed in Hirschsprung's disease could also be explained by the involvement of modifier genes, especially in its syndromic forms. In this review, we look at the chromosomal and Mendelian associations and their underlying signalling pathways, to obtain a better understanding of the pathogenetic mechanisms involved in developing aganglionosis of the distal bowel.

Etiopathological aspects of achalasia: lessons learned with Hirschsprung's disease

The etiology of primary esophageal achalasia is largely unknown. There is increasing evidence that genetic alterations might play an important but underestimated role. Current knowledge of the genetic base of Hirschsprung's disease in contrast is far more detailed. The two enteric neuropathies have several clinical features in common. This association may also exist on a cellular and molecular level. The aim of this review is to enlighten those etiopathogenetic concepts of Hirschsprung's disease that seem to be useful in uncovering the pathological processes causing achalasia. Three aspects are looked at: (i) the genetic base of Hirschsprung's disease, particularly its major susceptibility gene rearranged during transfection and its potential reference to achalasia; (ii) the altered motor functions in both conditions with loss of inhibitory innervation and interstitial cell pathology; and (iii) the involvement of these motility disorders in genetic syndromes.

Hirschsprung disease: a developmental disorder of the enteric nervous system

Hirschsprung disease (HSCR), which is also called congenital megacolon or intestinal aganglionosis, is characterized by an absence of enteric (intrinsic) neurons from variable lengths of the most distal bowel. Because enteric neurons are essential for propulsive intestinal motility, infants with HSCR suffer from severe constipation and have a distended abdomen. Currently the only treatment is surgical removal of the affected bowel. HSCR has an incidence of around 1:5,000 live births, with a 4:1 male:female gender bias. Most enteric neurons arise from neural crest cells that emigrate from the caudal hindbrain and then migrate caudally along the entire gut. The absence of enteric neurons from variable lengths of the bowel in HSCR results from a failure of neural crest-derived cells to colonize the affected gut regions. HSCR is therefore regarded as a neurocristopathy. HSCR is a multigenic disorder and has become a paradigm for understanding complex factorial disorders. The major HSCR susceptibility gene is RET. The penetrance of several mutations in HSCR susceptibility genes is sex-dependent. HSCR can occur as an isolated disorder or as part of syndromes; for example, Type IV Waardenburg syndrome is characterized by deafness and pigmentation defects as well as intestinal aganglionosis. Studies using animal models have shown that HSCR genes regulate multiple processes including survival, proliferation, differentiation, and migration. Research into HSCR and the development of enteric neurons is an excellent example of the cross fertilization of ideas that can occur between human molecular geneticists and researchers using animal models. WIREs Dev Biol 2013, 2:113-129. doi: 10.1002/wdev.57 For further resources related to this article, please visit the WIREs website.

Achalasia--a disease of unknown cause that is often diagnosed too late

INTRODUCTION

Many physicians are inadequately familiar with the clinical features of achalasia. Often, it is not diagnosed until years after the symptoms arise. This is unfortunate, because a delay in diagnosis worsens the prognosis.

METHODS

Selective review of the literature.

RESULTS

Achalasia has a lifetime prevalence of 1:10 000. It is a neurodegenerative disorder in which the neurons of the myenteric plexus are lost, leading to dysfunction of the lower esophageal sphincter and to a derangement of esophageal peristalsis. In the final stage of achalasia, esophageal motility is irreversibly impaired, and complications ensue because of the retention of food that is no longer transported into the stomach. Aspiration causes pulmonary disturbances in up to half of all patients with achalasia. There may also be inflammation of the esophageal mucosa (retention esophagitis); this, in turn, is a risk factor for esophageal cancer, which arises in 4% to 6% of patients. The cause of achalasia is not fully known, but autoimmune processes appear to be involved in patients with a genetic susceptibility to the disease.

CONCLUSION

Achalasia should be diagnosed as early as possible, so that complications can be prevented. In addition, guidelines should be established for cancer prevention in achalasia patients. Currently ongoing studies of the molecular causes of achalasia will probably help us understand its pathophysiology.

Motility problems in the intellectually challenged child, adolescent, and young adult

Gastrointestinal (GI) motility problems represent an important cause of morbidity and sometimes mortality in patients affected by developmental disorders. This article describes motility disorders in Down syndrome, cerebral palsy, familial dysautonomia, and Williams syndrome. These problems do not often receive appropriate attention, either because priority is given to other medical aspects of the disorder, or because of the inability of affected children to communicate their symptoms. A better approach to the diagnosis and treatment of GI disorders is required to improve quality of life and minimize morbidity and mortality among patients with developmental disorders.

Effects of environment and lifestyle on gastroesophageal reflux disease

BACKGROUND

Gastroesophageal reflux disease (GERD) is comprised of a spectrum of related disorders, including hiatal hernia, reflux disease with its associated symptoms, erosive esophagitis, peptic stricture, Barrett's esophagus, and esophageal adenocarcinoma. Besides multiple pathophysiological associations among these disorders, they are also characterized by their comorbid occurrence in identical patients and by their similar epidemiologic behavior. The occurrence of GERD is shaped by marked temporal and geographic variations, suggesting the influence of environmental risk factors in the etiology of these diseases.

VARIATIONS BY TIME, GEOGRAPHY, AND RACE

Between 1975 and 2005, the incidence of GERD and esophageal adenocarcinoma increased fivefold in most Western countries. The incidence of GERD also appears to be rising in the most developed countries of Asia. All severe forms of GERD, such as erosive esophagitis, peptic stricture, Barrett's metaplasia, and esophageal adenocarcinoma, are more common among whites than other ethnic groups.

AFFLUENCE AND OBESITY AS RISK FACTORS

Barrett's esophagus and esophageal adenocarcinoma tend to occur slightly more often in subjects with higher income. Overweight and obesity contribute to the development of hiatal hernia, increase intra-abdominal pressure, and promote gastroesophageal reflux. Weight gain increases reflux symptoms, whereas weight loss decreases such symptoms. Other risk factors, such as smoking, alcohol, dietary fat, or drugs, play only a minor role in shaping the epidemiologic patterns of GERD.

PROTECTION THROUGH HELICOBACTER PYLORI

On a population level, a high prevalence of H. pylori infection is likely to reduce levels of acid secretion and protect some carriers of the infection against reflux disease and its associated complications. Several studies have confirmed a lesser prevalence of H. pylori among subjects with than without GERD. Until recently, populations in Africa and Asia may have been protected against the development of GERD and esophageal adenocarcinoma by their higher prevalence of H. pylori infection.

CONCLUSION

The study of environmental risk factors may provide an opportunity to better understand GERD and develop a means of its prevention.

Hirschsprung's disease and the brain

A link between factors governing brain development and the development of the ENS is not surprising as both processes are largely controlled by the same or similar neural growth factors which are expressed at more or less in the same spatio-temporal time frame. Hirschsprung's disease (HSCR) occurs as an isolated phenotype in 70% of cases but is associated with other congenital abnormalities and syndromic phenotypes in the remainder, with CNS anomalies making up 6.78%. These associations may be underestimated and are possibly pathogenetically linked to genetic associations and probable gene-gene interaction. In this review we explore known syndromes and other ENS associations of HSCR, looking at possible pathogenetic associations. We point out that borderline cognitive abilities, attention-deficit disorders and possible epileptic seizures in Hirschsprung's patients should be fully investigated. We recognise that this group of patients remain a challenge from a clinical and functional management point of view, and suggest possible management guidelines.

Childhood constipation; an overview of genetic studies and associated syndromes

Constipation is a common problem in children but little is known about its exact pathophysiology. Environmental, behavioural but also genetic factors are thought to play a role in the aetiology of childhood constipation. We provide an overview of genetic studies performed in constipation. Until now, linkage studies, association studies and direct gene sequencing have failed to identify mutations in specific genes associated with constipation. We show that along with functional constipation, there are numerous clinical syndromes associated with childhood constipation. These syndromic forms of constipation appear to be the result of mutations in genes affecting all aspects of the normal physiology of human defecation. We stress that syndromic causes of childhood constipation should be considered in the evaluation of a constipated child.

Treating acid reflux disease in patients with Down syndrome: pharmacological and physiological approaches

Down syndrome (DS) is often accompanied by gastrointestinal disease, occurring mainly in early infancy and frequently requiring therapy. Among motility disorders, the most frequent is gastroesophageal reflux disease (GERD), which may often be misdiagnosed because of its atypical manifestations. Early diagnosis of esophageal functional disorders is essential to prevent respiratory problems, growth retardation in children, weight loss in adults, and to establish the correct type of surgery if needed. Furthermore, the involvement of the enteric nervous system in the pathophysiology of GERD in DS is not yet completely understood but seems supported by much evidence. In fact DS is often associated with motor disorders and this evidence must be considered in the choice of therapy: in particular all options available to improve motility seem to be effective in these patients. The effectiveness of therapy is strictly related to the rate of mental impairment, so that modulating therapy is essential, especially in view of the severity of the neurological status.

Hirschsprung's disease in the neurologically challenged child

BACKGROUND

The association between Hirschsprung's disease (HSCR) and central nervous system (CNS) anomalies and syndromes is interesting because of similar developmental pathways. In addition to associated syndromes (e.g., Trisomy 21), these include brain anomalies, mental retardation and growth, ear and hearing deformities, eye hypoplasia, and craniofacial abnormalities, suggesting an neurocristopathy. This group of patients present with neurological challenges and have special challenges in management especially in the older child and adolescent.

METHODS

We retrospectively investigated 32 patients with significant HSCR-associated neurological challenges out of a local database of 555 HSCRs (6%). Data were analyzed with details of neurological problem, treatment, complications, and mortality. Long-term outcome was assessed clinically.

RESULTS

A total of 32 neurologically challenged children were studied. The male/female ratio was 1.7:1 and all ethnic groups were affected. Abnormalities and syndromes included Down (n = 16) and probable Mowat-Wilson (n = 2) syndromes. Other abnormalities included ophthalmic problems (n = 8), CNS and brain abnormalities (n = 8). Mortality (22%) was mostly related to enterocolitis, particularly in Trisomy 21, ophthalmic problems (n = 8), CNS and brain abnormalities (n = 8). Follow-up age range was 1-34 years (8 years, adolescence and beyond). The outcome was variable, concomitant medical problems were common. Several patients failed to achieve satisfactory continence.

CONCLUSION

The association of neurological difficulties in patients with HSCR presents many challenges. Management could involve the exploration and evaluation of alternative treatment choices.

Achalasia: will genetic studies provide insights?

Despite increasing understanding of the pathophysiology of achalasia, the etiology of this esophageal motility disorder remains largely unknown. However, the occurrence of familial achalasia and its association with well-defined genetic syndromes suggest the involvement of genetic factors. Mutant mouse models display gastrointestinal disturbances that are similar to those observed in achalasia patients. The candidate gene approach has revealed some promising results; however, it has not established conclusive links to specific genes so far. The aim of this review was to summarize current knowledge of the genetics of achalasia. We also discuss the extent to which our understanding of achalasia is likely to be enhanced through future molecular genetic research.

Achalasia: will genetic studies provide insights?

Despite increasing understanding of the pathophysiology of achalasia, the etiology of this esophageal motility disorder remains largely unknown. However, the occurrence of familial achalasia and its association with well-defined genetic syndromes suggest the involvement of genetic factors. Mutant mouse models display gastrointestinal disturbances that are similar to those observed in achalasia patients. The candidate gene approach has revealed some promising results; however, it has not established conclusive links to specific genes so far. The aim of this review was to summarize current knowledge of the genetics of achalasia. We also discuss the extent to which our understanding of achalasia is likely to be enhanced through future molecular genetic research.

What we have learned about colonic motility: normal and disturbed

PURPOSE OF REVIEW

Disorders of colonic motor and sensory function are common among children and adults and pose significant diagnostic and therapeutic challenges; the purpose of this review, therefore, was to critically assess the recent literature on this topic.

RECENT FINDINGS

Considerable progress has been made at the ultrastructural, molecular and electrophysiological level in understanding the normal functions of the muscles, nerves and interstitial cells that generate and control colonic motility. Furthermore, abnormalities in these cell types and in the interstitial cells of Cajal, in particular, have been identified in a number of disease states. Testing of colonic motor and sensory function in clinical practice continues to be a challenge due, in part, not only to the technical issues presented by accessing the organ but also to the intrinsic variability of its physiology. These have not been auspicious times for advances in the therapy of disturbed colonic motility; new agents or new applications for 'old' agents continue to be explored as are more innovative approaches such as those based on neural stimulation and cell therapy.

SUMMARY

Considerable progress has been made in understanding the basic pathophysiology of colonic dysmotility; clinical diagnostics and therapeutics continue to lag behind.

Practical pathology and genetics of Hirschsprung's disease

Diagnosis and management of Hirschsprung's disease (HSCR) requires understanding of the malformation's anatomic features and multigenic nature. Rectal biopsies, intraoperative frozen sections, and resection specimens provide invaluable information. Extraction of these data requires thoughtful biopsy technique, adequate histologic sections, histochemistry, and collaboration of surgeon and pathologist. Critical consideration of transition zone anatomy and published studies of "transition zone pull through" indicate that more research is needed to determine how much ganglionic bowel should be resected from HSCR patients. Many HSCR-susceptibility genes have been identified, but mutational analysis has limited practical value unless family history or clinical findings suggest syndromic HSCR.