Infantile hypertrophic pyloric stenosis--genetics and syndromes

Evaluating the molecular and genetic mechanisms underlying gut motility disorders

INTRODUCTION

Gastrointestinal (GI) motility disorders comprise a wide range of different diseases affecting the structural or functional integrity of the GI neuromusculature. Their clinical presentation and burden of disease depends on the predominant location and extent of gut involvement as well as the component of the gut neuromusculature affected.

AREAS COVERED

A comprehensive literature review was conducted using the PubMed and Medline databases to identify articles related to GI motility and functional disorders, published between 2016 and 2023. In this article, we highlight the current knowledge of molecular and genetic mechanisms underlying GI dysmotility, including disorders of gut-brain interaction, which involve both GI motor and sensory disturbance.

EXPERT OPINION

Although the pathophysiology and molecular mechanisms underlying many such disorders remain unclear, recent advances in the assessment of intestinal tissue samples, genetic testing with the application of 'omics' technologies and the use of animal models will provide better insights into disease pathogenesis as well as opportunities to improve therapy.

Single-incision versus conventional laparoscopic pyloromyotomy for pediatric hypertrophic pyloric stenosis: a systematic review and meta-analysis

PURPOSE

To assess the safety and efficacy of single-incision versus conventional laparoscopic pyloromyotomy in pediatrics, we conducted a systematic review and meta-analysis.

METHODS

A literature search was conducted to identify studies that compared single-incision laparoscopic pyloromyotomy (SILP) and conventional laparoscopic pyloromyotomy (CLP) for infants with hypertrophic pyloric stenosis (HPS). Meta-analysis was used to pool and compare variables such as operative time, time to full feeding, length of hospital stay, mucosal perforation, inadequate pyloromyotomy, wound infection, incisional hernia and overall complications.

RESULTS

Among the 490 infants with HPS in the seven studies, 205 received SILP and 285 received CLP. There was significant longer time to full feeding for SILP compared with CLP. However, pooling the results for SILP and CLP revealed no significant difference in operative time, length of hospital stay and postoperative complications.

CONCLUSIONS

SILP is a safe, feasible and effective surgical procedure for infants with HPS when compared to CLP. SILP is equivalent to CLP in terms of operative time, length of hospital stay and postoperative complications. We conclude that LS should be considered an acceptable option for HPS.

Transumbilical single-site two incision laparoscopic pyloromyotomy for pediatric hypertrophic pyloric stenosis

PURPOSE

A new novel technique for the treatment of pediatric hypertrophic pyloric stenosis (HPS), transumbilical single-site laparoscopic pyloromyotomy with a single instrument (TUSSLP), was introduced. TUSSLP was compared with the transabdominal three-site laparoscopic pyloromyotomy (TATSLP) procedure.

METHODS

Patients with HPS who underwent TUSSLP and TATSLP between January 2016 and September 2020 were assigned to group A and group B, respectively. The descriptive variables, perioperative clinical characteristics and postoperative follow-up results were retrospectively analyzed and compared between the 2 groups. The primary outcome of this study was the rate of switching to conventional pyloromyotomy.

RESULTS

Sixty-four patients were enrolled in this study. Of these patients, 29 (22 males, 7 females, 54.4 ± 22.6 days) who received TUSSLP were assigned to group A. The remaining 35 (28 males, 7 females, 54.5 ± 27.6 days) who received TATSLP were assigned to group B. The data of preoperative patient variables were comparable between the 2 groups (P > 0.05). The mean operative time (ORT) was 28.1 ± 5.6 min in group A, which was not significantly different from 25.8 ± 3.1 min in group B (P = 0.25). The other perioperative features were not significantly different between the 2 groups (P > 0.05). During follow-up (39.1 ± 14.7 m in group A and 35.4 ± 16.1 m in group B, P = 0.51), no significant difference was observed in the overall incidence of vomiting between the 2 groups (P = 0.26).

CONCLUSIONS

TUSSLP is a feasible and reliable minimally invasive method for HPS. It has the advantages of an improved cosmetic appearance. The postoperative follow-up results of TUSSLP are comparable with those of TATSLP.

Hypertrophic pyloric stenosis masked by kidney failure in a male infant with a contiguous gene deletion syndrome at Xp22.31 involving the steroid sulfatase gene: case report

Background

Contiguous gene deletion syndrome at Xp22.3 resulting in nullisomy in males or Turner syndrome patients typically encompasses the steroid sulfatase gene (STS) and contiguously located other genes expanding the phenotype. In large deletions, that encompass also the Kallmann syndrome 1 gene (KAL1), occasionally infantile hypertrophic pyloric stenosis (IHPS) and congenital anomalies of the kidney and urinary tract (CAKUT) have been reported.

Patient presentation

We report on a male newborn with family history in maternal uncle of renal abnormalities and short stature still without ichthyosiform dermatosis. The baby presented CAKUT with kidney failure and progressive vomiting. Renal bicarbonate loss masked hypochloremic and hypokalemic metabolic alkalosis classically present in IHPS and delayed its diagnosis. Antropyloric ultrasound examination and cystourethrography were diagnostic. After Fredet-Ramstedt extramucosal pyloromyotomy feeding and growing was regular and he was discharged home. Comparative whole-genome hybridization detected a maternal inherited interstitial deletion of 1.56 Mb on Xp22.31(6,552,712_8,115,153) × 0 involving the STS gene, but not the KAL1 gene.

Conclusions

Aberrant cholesterol sulfate storage due to STS deletion as the underlying pathomechanism is not limited to oculocutaneous phenotypes but could also lead to co-occurrence of both IHPS and kidney abnormalities, as we report. Thus, although these two latter pathologies have a high incidence in the neonatal age, their simultaneous association in our patient is resembling not a chance but a real correlation expanding the clinical spectrum associated with Xp22.31 deletions.

A Case of UDP-Galactose 4'-Epimerase Deficiency Associated with Dyshematopoiesis and Atrioventricular Valve Malformations: An Exceptional Clinical Phenotype Explained by Altered N-Glycosylation with Relative Preservation of the Leloir Pathway

The generalized form of UDP-galactose-4'-epimerase (GALE) deficiency causes hypotonia, failure to thrive, cataracts, and liver failure. Individuals with non-generalized forms may remain asymptomatic with uncertain long-term outcomes. We report a 2-year-old child compound heterozygous for GALE p.R51W/p.G237D who never developed symptoms of classic galactosemia but has a history of congenital combined mitral and tricuspid valve malformation and pyloric stenosis, and presented with pancytopenia. Variant pathogenicity was supported by predictive computational tools and decreased GALE activity measured in erythrocytes. GALE function extends to the biosynthesis of glycans by epimerization of UDP-N-acetyl-galactosamine and -glucosamine. Interrogation of the Gene Ontology consortium database revealed several putative proteins involved in normal hematopoiesis and atrioventricular valve morphogenesis, requiring N-glycosylation for adequate functionality. We hypothesize that by limiting substrate supply due to GALE deficiency, alterations in N-linked protein glycosylation can explain the patient's phenotype.

Infantile hypertrophic pyloric stenosis in patients with esophageal atresia

BACKGROUND

Patients born with esophageal atresia (EA) have a higher incidence of infantile hypertrophic pyloric stenosis (IHPS), suggestive of a relationship. A shared etiology makes sense from a developmental perspective as both affected structures are foregut derived. A genetic component has been described for both conditions as single entities and EA and IHPS are variable components in several monogenetic syndromes. We hypothesized that defects disturbing foregut morphogenesis are responsible for this combination of malformations.

METHODS

We investigated the genetic variation of 15 patients with both EA and IHPS with unaffected parents using exome sequencing and SNP array-based genotyping, and compared the results to mouse transcriptome data of the developing foregut.

RESULTS

We did not identify putatively deleterious de novo mutations or recessive variants. However, we detected rare inherited variants in EA or IHPS disease genes or in genes important in foregut morphogenesis, expressed at the proper developmental time-points. Two pathways were significantly enriched (p < 1 × 10^-5 ): proliferation and differentiation of smooth muscle cells and self-renewal of satellite cells.

CONCLUSIONS

None of our findings could fully explain the combination of abnormalities on its own, which makes complex inheritance the most plausible genetic explanation, most likely in combination with mechanical and/or environmental factors. As we did not find one defining monogenetic cause for the EA/IHPS phenotype, the impact of the corrective surgery could should be further investigated.

Homozygous variants in MAPRE2 and CDON in individual with skin folds, growth delay, retinal coloboma, and pyloric stenosis

Cases with multiple molecular diagnoses are challenging to diagnose clinically, yet may be resolved by unbiased exome sequencing analysis. We report an infant with developmental delay, severe growth delay, dysmorphic features, and multiple congenital anomalies including retinal coloboma, congenital pyloric stenosis, and circumferential skin creases. Exome sequencing identified a homozygous missense variant in MAPRE2 and a homozygous stopgain (nonsense) variant in CDON. Variants in MAPRE2, encoding a regulator of microtubule dynamics, lead to congenital symmetric circumferential skin creases type 2, with associated dysmorphism, small growth parameters, and congenital cardiac and genital anomalies. Monoallelic variants in CDON, encoding a coreceptor for sonic hedgehog, have been associated with autosomal dominant pituitary stalk interruption syndrome and holoprosencephaly. Cdon-/- mice have multiple eye defects including coloboma, consistent with the observed human phenotype. Thus, the complex phenotypic presentation of the infant may potentially be attributed to a dual molecular diagnosis. Furthermore, we present CDON as a candidate gene for coloboma formation in addition to the known holoprosencephaly phenotype, and propose to expand the allelic spectrum of CDON to variants associated with autosomal recessive inheritance in addition to dominant inheritance.

Genome-wide meta-analysis identifies BARX1 and EML4-MTA3 as new loci associated with infantile hypertrophic pyloric stenosis

Infantile hypertrophic pyloric stenosis (IHPS) is a disorder of young infants with a population incidence of ∼2/1000 live births, caused by hypertrophy of the pyloric sphincter smooth muscle. Reported genetic loci associated with IHPS explain only a minor proportion of IHPS risk. To identify new risk loci, we carried out a genome-wide meta-analysis on 1395 surgery-confirmed cases and 4438 controls, with replication in a set of 2427 cases and 2524 controls. We identified and replicated six independent genomic loci associated with IHPS risk at genome wide significance (P < 5 × 10-8), including novel associations with two single nucleotide polymorphisms (SNPs). One of these SNPs, rs6736913 [odds ratio (OR) = 2.32; P = 3.0 × 10-15], is a low frequency missense variant in EML4 at 2p21. The second SNP, rs1933683 (OR = 1.34; P = 3.1 × 10-9) is 1 kb downstream of BARX1 at 9q22.32, an essential gene for stomach formation in embryogenesis. Using the genome-wide complex trait analysis method, we estimated the IHPS SNP heritability to be 30%, and using the linkage disequilibrium score regression method, we found support for a previously reported genetic correlation of IHPS with lipid metabolism. By combining the largest collection of IHPS cases to date (3822 cases), with results generalized across populations of different ancestry, we elucidate novel mechanistic avenues of IHPS disease architecture.

Co-occurrence of infantile hypertrophic pyloric stenosis and congenital heart defects: a nationwide cohort study

BACKGROUND

Recent studies suggest that infantile hypertrophic pyloric stenosis (IHPS) and congenital heart defects (CHDs) may share some genetic risk factors, but little is known about the co-occurrence of the two conditions in patients.

METHODS

Our study cohort included 2,212,756 persons born in Denmark 1977-2013. We identified patients with IHPS and CHD in the National Patient Register. Using log-linear Poisson regression, we estimated the (incidence) rate ratios (RRs) comparing the rate of IHPS among children with a CHD diagnosis (exposed) and the rate among those without such a diagnosis.

RESULTS

Twenty-seven thousand three hundred and fifty-seven children in the cohort were diagnosed with CHD out of whom 85 developed IHPS (RR = 2.62, 95% confidence interval (CI) 2.09-3.22]). The results were similar for those with and without other congenital malformations, for preterm and term deliveries, and for both sexes. There was, however, a significant effect of calendar period (P = .003). In the period 1977-1996, the RR of IHPS given a CHD diagnosis was 1.96 (95% CI 1.41-2.64); in the period 1997-2014, the RR was 3.75 (95% CI 2.74-4.99).

CONCLUSION

CHD was associated with an increased risk of IHPS. Further research is needed to delineate molecular-level mechanisms that may affect both conditions.

Congenital absence of lingual frenum in a non-syndromic patient: a case report

Background

The lingual frenum is a fold of mucous membrane connecting the ventral tongue to the floor of the mouth. In general, lingual frenum serves multiple roles; its main function is to support the tongue and aid in limiting its movement in different directions. Any anatomical or functional deficiency of lingual frenum may have an impact on tongue functions based on its severity. Historically, the absence of lingual frenum was linked to multiple genetic and developmental conditions such as infantile hypertrophic pyloric stenosis, non-syndromic ankyloglossia diseases, and Ehlers–Danlos syndromes and was never reported in otherwise healthy individuals.

Case presentation

We report the absence of lingual frenum in an otherwise healthy 21-year-old Middle Eastern woman diagnosed during a routine dental examination.

Conclusion

To the best of our knowledge, this is the first case to be reported in the literature with similar clinical presentation. Even without a significant impact on tongue movement or speech, it is important for health practitioners to be aware of such conditions and evaluation steps for diagnosis and management.

Malformations, choristomas, and hamartomas of the gastrointestinal tract and pancreas

Congenital and hamartomatous lesions of the gastrointestinal tract cause diagnostic challenges for surgical pathologists. Many of these are merely histologic curiosities, whereas others have substantial clinical implications because they herald cancer syndromes or associated anomalies. Although a comprehensive discussion of all developmental abnormalities that can occur in the gastrointestinal tract is beyond the scope of a single manuscript, some entities are more likely to be encountered by surgical pathologists, have important clinical consequences, or pose diagnostic difficulties. The purpose of this review is to discuss the more common malformations and choristomas, as well as hamartomatous lesions that may be clinically important due to their risk for cancer development, frequent associations with heritable cancer syndromes and other anomalies, or potential to simulate other entities.

ACTG2-Associated Visceral Myopathy With Chronic Intestinal Pseudoobstruction, Intestinal Malrotation, Hypertrophic Pyloric Stenosis, Choledochal Cyst, and a Novel Missense Mutation

Primary visceral myopathy caused by a pathogenic mutation in the gene encoding the enteric smooth muscle actin gamma 2 ( ACTG2) affects gastrointestinal and genitourinary tracts and often presents as chronic intestinal pseudoobstruction. We present a case of pediatric onset chronic intestinal pseudoobstruction associated with a novel missense ACTG2 mutation c.439G>T/p.G147C. In addition to the known disease manifestations of feeding intolerance and intestinal malrotation, our patient had a late-onset hypertrophic pyloric stenosis and a late-onset choledochal cyst, the former of which has not previously been described in patients with ACTG2-associated visceral myopathy.

Pyloric stenosis: an enigma more than a century after the first successful treatment

Despite hypertrophic pyloric stenosis (HPS) being one of the most frequently treated pediatric surgical conditions, its etiology remains incompletely understood. We review the diagnosis and treatment of this condition with an emphasis on the evolution of surgical techniques that led to laparoscopic pyloromyotomy, the most frequently performed technique for HPS today. In addition, we review key developments in the understanding of HPS etiology and treatment, including the postulated etiology of work-induced hypertrophy of the pylorus, its association with prokinetic macrolide antibiotics, and the emerging role of atropine sulfate as a medical treatment for HPS or a rescue treatment for incomplete myotomy.

Consideration of pyloric stenosis as a cause of feeding dysfunction in children with cyanotic heart disease

Feeding difficulty has been reported at a higher incidence in infants with cyanotic heart disease and single ventricle physiology necessitating specialized feeding strategies. However, structural causes of feed intolerance in this subset of patients should not be ignored. This case series highlights three recent cases of pyloric stenosis in infants with left-sided obstructive lesions at our institution. In all three cases, the initial presumed diagnosis was feeding intolerance related to heart disease, and there was significant clinical improvement following identification and correction of pyloric stenosis.

Application of color Doppler ultrasound combined with Doppler imaging artifacts in the diagnosis and estimate of congenital hypertrophic pyloric stenosis

Congenital Hypertrophic Pyloric Stenosis (CHPS) is a disease condition that is caused as a result of pylorus wall hypertrophy and hyperplasia. In this study, we used color Doppler flow imaging (CDFI) and Doppler artifacts technique to observe the blood flow of hypertrophic pylorus tissue and the dynamic imaging of liquid passing through the pyloric canal in CHPS infants. 65 cases of CHPS infants and 50 infants without CHPS served as control group. We found that there were statistically significant differences between the blood flow grade of muscular layer and mucosal layer between CHPS and control infants, but no significant differences were observed in the same group. Doppler artifacts technique demonstrated the whole process of contrast agent flow through pyloric canal was directly observed in 35 of 65 subjects, and the internal diameter of the pyloric canal was 1.93 ± 0.33mm.Conclusion that CDFI combined with color Doppler artifacts technique was proved to be effective to observe the distribution feature and blood flow grade in each layer of pyloric canal in CHPS patients. This method provides the evidence for judging the degree of pyloric stenosis clinically, and furnishes the basis of therapy along with its clinical significance and good application value.

Intestinal microbiota as a tetrahydrobiopterin exogenous source in hph-1 mice

Tetrahydrobiopterin (BH4) is a cofactor of a number of regulatory enzymes. Although there are no known BH4 exogenous sources, the tissue content of this biopterin increases with age in GTP cyclohydrolase 1-deficient hyperphenylalaninemia-1 (hph-1) mice. Since certain bacteria are known to generate BH4, we hypothesize that generation of this biopterin by the intestinal microbiota contributes to its tissue increase in hph-1 adult mice. The goal of this study was to comparatively evaluate hph-1 mice and wild-type C57Bl/6 controls for the presence of intestinal BH4-producing bacteria. Newborn and adult mice fecal material was screened for 6-pyruvoyltetrahydropterin synthase (PTPS-2) an enzyme only present in BH4-generating bacteria. Adult, but not newborn, wild-type control and hph-1 mouse fecal material contained PTPS-2 mRNA indicative of the presence of BH4-generating bacteria. Utilizing chemostat-cultured human fecal bacteria, we identified the PTPS-2-producing bacteria as belonging to the Actinobacteria phylum. We further confirmed that at least two PTPS-2-producing species, Aldercreutzia equolifaciens and Microbacterium schleiferi, generate BH4 and are present in hph-1 fecal material. In conclusion, intestinal Actinobacteria generate BH4. This finding has important translational significance, since manipulation of the intestinal flora in individuals with congenital biopterin deficiency may allow for an increase in total body BH4 content.

Convergence of inhibitory neural inputs regulate motor activity in the murine and monkey stomach

Inhibitory motor neurons regulate several gastric motility patterns including receptive relaxation, gastric peristaltic motor patterns, and pyloric sphincter opening. Nitric oxide (NO) and purines have been identified as likely candidates that mediate inhibitory neural responses. However, the contribution from each neurotransmitter has received little attention in the distal stomach. The aims of this study were to identify the roles played by NO and purines in inhibitory motor responses in the antrums of mice and monkeys. By using wild-type mice and mutants with genetically deleted neural nitric oxide synthase (Nos1^-/-) and P2Y1 receptors (P2ry1^-/-) we examined the roles of NO and purines in postjunctional inhibitory responses in the distal stomach and compared these responses to those in primate stomach. Activation of inhibitory motor nerves using electrical field stimulation (EFS) produced frequency-dependent inhibitory junction potentials (IJPs) that produced muscle relaxations in both species. Stimulation of inhibitory nerves during slow waves terminated pacemaker events and associated contractions. In Nos1^-/- mice IJPs and relaxations persisted whereas in P2ry1^-/- mice IJPs were absent but relaxations persisted. In the gastric antrum of the non-human primate model Macaca fascicularis, similar NO and purine neural components contributed to inhibition of gastric motor activity. These data support a role of convergent inhibitory neural responses in the regulation of gastric motor activity across diverse species.

Genetics of enteric neuropathies

Abnormal development or disturbed functioning of the enteric nervous system (ENS), the intrinsic innervation of the gastrointestinal tract, is associated with the development of neuropathic gastrointestinal motility disorders. Here, we review the underlying molecular basis of these disorders and hypothesize that many of them have a common defective biological mechanism. Genetic burden and environmental components affecting this common mechanism are ultimately responsible for disease severity and symptom heterogeneity. We believe that they act together as the fulcrum in a seesaw balanced with harmful and protective factors, and are responsible for a continuum of symptoms ranging from neuronal hyperplasia to absence of neurons.

Stomach development, stem cells and disease

The stomach, an organ derived from foregut endoderm, secretes acid and enzymes and plays a key role in digestion. During development, mesenchymal-epithelial interactions drive stomach specification, patterning, differentiation and growth through selected signaling pathways and transcription factors. After birth, the gastric epithelium is maintained by the activity of stem cells. Developmental signals are aberrantly activated and stem cell functions are disrupted in gastric cancer and other disorders. Therefore, a better understanding of stomach development and stem cells can inform approaches to treating these conditions. This Review highlights the molecular mechanisms of stomach development and discusses recent findings regarding stomach stem cells and organoid cultures, and their roles in investigating disease mechanisms.

Gastric and pyloric sphincter muscle function and the developmental-dependent regulation of gastric content emptying in the rat

Feeding intolerance is a common issue in the care of preterm neonates. The condition manifests as delayed emptying of gastric contents and represents a therapeutic challenge, since the factors accounting for its manifestations are unknown. The main goal of this study was to comparatively investigate the age-related function of rat gastric and pyloric smooth muscle and their putative regulators. We hypothesized that a reduced gastric muscle contraction potential early in life contributes to the delayed gastric emptying of the newborn. Newborn and adult rat gastric (fundus) and pyloric sphincter tissues were comparatively studied in vitro. Shortening of the tissue-specific dissociated smooth muscle cell was evaluated, and expression of the key regulatory proteins Rho-associated kinase 2 and myosin light chain kinase was determined. Gastric and pyloric smooth muscle cell shortening was significantly greater in the adult than the respective newborn counterpart. Expression of myosin light chain kinase and Rho-associated kinase 2 was developmentally regulated and increased with age. Pyloric sphincter muscle expresses a higher neuronal nitric oxide synthase and phosphorylated vasodilator-stimulated phosphoprotein content in newborn than adult tissue. Compared with later in life, the newborn rat gastropyloric muscle has a Ca(2+)-related reduced potential for contraction and the pyloric sphincter relaxation-dependent modulators are overexpressed. To the extent that these rodent data can be extrapolated to humans, the delayed gastric emptying in the newborn reflects reduced stomach muscle contraction potential, as opposed to increased pyloric sphincter tone.

Formula-feeding and hypertrophic pyloric stenosis: is there an association? A case-control study

BACKGROUND

The etiology of infantile hypertrophic pyloric stenosis (HPS) is not fully understood. The objective of this study was to determine whether formula-feeding is associated with increased incidence.

METHODS

This case-control study included HPS cases and controls admitted between 1992 and 2012. Demographic data including feeding method were collected from patient charts and analyzed.

RESULTS

We identified 882 HPS cases and 955 controls. The highest incidence of HPS presentation was in summer (P=0.0028). Infants with HPS were more likely to have been exclusively formula-fed, have a family history of HPS, and be male compared to infants in the control group (P<0.001); they were also more likely to live in rural areas, although not significantly so. After adjusting for family history, sex, place of residence, and season of presentation, exclusively formula-fed infants were 1.36 times more likely to develop HPS compared with exclusively breastfed infants (RR 1.36, 95% CI 1.18-1.57, P<0.005).

CONCLUSIONS

Formula-feeding is associated with significantly increased risk of HPS. Further investigation may help to determine the components of formula that simulate hypertrophy of the pylorus muscle, or the components of breast milk that are protective, as well as other influencing factors.

LEVEL OF EVIDENCE

3b.

White paper on guidelines concerning enteric nervous system stem cell therapy for enteric neuropathies

Over the last 20 years, there has been increasing focus on the development of novel stem cell based therapies for the treatment of disorders and diseases affecting the enteric nervous system (ENS) of the gastrointestinal tract (so-called enteric neuropathies). Here, the idea is that ENS progenitor/stem cells could be transplanted into the gut wall to replace the damaged or absent neurons and glia of the ENS. This White Paper sets out experts' views on the commonly used methods and approaches to identify, isolate, purify, expand and optimize ENS stem cells, transplant them into the bowel, and assess transplant success, including restoration of gut function. We also highlight obstacles that must be overcome in order to progress from successful preclinical studies in animal models to ENS stem cell therapies in the clinic.

Maternal factors in the origin of infantile hypertrophic pyloric stenosis: A population-based case-control study

In most patients affected by isolated infantile hypertrophic pyloric stenosis (IHPS) the etiology is largely unknown. Thus, the aim of this study was to estimate possible maternal risk factors in the origin of IHPS. The study samples included 241 cases with IHPS, 357 matched controls and 38,151 population controls without any defect in the population-based large dataset of the Hungarian Case-Control Surveillance of Congenital Abnormalities, 1980-1996. Exposures that had been medically recorded in prenatal maternity logbooks during the critical period of IHPS were evaluated separately. The findings of this case-control study suggested that--beyond the well-known robust male excess (85.5%)--maternal hyperthyroidism (OR with 95% CI: 4.17, 1.53-11.38) and oral nalidixic acid treatment (OR with 95% CI: 6.53, 3.03-14.06) associated with a higher risk for IHPS in their children. In conclusion, our findings suggest that cases with IHPS had mothers with a higher proportion of hyperthyroidism and nalidixic acid treatment during pregnancy.

Birth outcomes of male and female patients with infantile hypertrophic pyloric stenosis--a population-based case-control study

OBJECTIVE

Most of the patients are affected by isolated infantile hypertrophic pyloric stenosis (IHPS) beyond the polygenic predisposition, the other factors in the multifactorial etiology are largely unknown. The main characteristic of IHPS is the robust male predominance, thus the aim of this study was to analyze birth outcomes in males and females whether they are different or not.

METHODS

The study samples included 241 cases with IHPS, 357 matched, and 38,151 population controls without any defect in the population-based large dataset of the Hungarian Case-Control Surveillance of Congenital Abnormalities, 1980-1996.

RESULTS

The findings of this case-control study confirmed the well-known strong male excess (85.5%). The mean gestational age was somewhat longer and it is associated with a lower rate of preterm births. Mean birth weight did not show significant differences among the study groups, but the rate of low birthweight was higher in cases with IHPS. However, these differences were found only in males. Thus, intrauterine fetal growth restriction is characteristic only for male cases with IHPS.

CONCLUSIONS

Our study confirmed the well-known obvious male excess of cases with IHPS, but our findings suggest some differences in birth outcomes of male and female cases. Male cases with IHPS had intrauterine fetal growth restriction while females did not. These data may indicate some differences in the pathogenesis of IHPS in males and females.

Infantile hypertrophic pyloric stenosis (IHPS): a study of its pathophysiology utilizing the newborn hph-1 mouse model of the disease

Infantile hypertrophic pyloric stenosis (IHPS) is a common disease of unknown etiology. The tetrahydrobiopterin (BH4)-deficient hyperphenylalaninemia-1 (hph-1) newborn mouse has a similar phenotype to the human condition. For hph-1 and wild-type control animals, pyloric tissue agonist-induced contractile properties, reactive oxygen species (ROS) generation, cGMP, neuronal nitric oxide synthase (nNOS) content, and Rho-associated protein kinase 2 (ROCK-2) expression and activity were evaluated. Primary pyloric smooth muscle cells from wild-type newborn animals were utilized to evaluate the effect of BH4 deficiency. One-week-old hph-1 mice exhibited a fourfold increase (P < 0.01) in the pyloric sphincter muscle contraction magnitude but similar relaxation values when compared with wild-type animals. The pyloric tissue nNOS expression and cGMP content were decreased, whereas the rate of nNOS uncoupling increased (P < 0.01) in 1-wk-old hph-1 mice when compared with wild-type animals. These changes were associated with increased pyloric tissue ROS generation and elevated ROCK-2 expression/activity (P < 0.05). At 1-3 days of age and during adulthood, the gastric emptying rate of the hph-1 mice was not altered, and there were no genotype differences in pyloric tissue ROS generation, nNOS expression, or ROCK-2 activity. BH4 inhibition in pyloric smooth muscle cells resulted in increased ROS generation (P < 0.01) and ROCK-2 activity (P < 0.05). Oxidative stress upregulated ROCK-2 activity in pyloric tissue, but no changes were observed in newborn fundal tissue in vitro. We conclude that ROS-induced upregulation of ROCK-2 expression accounts for the increased pyloric sphincter tone and nNOS downregulation in the newborn hph-1 mice. The role of ROCK-2 activation in the pathogenesis of IHPS warrants further study.

Assessing neonates for neonatal abstinence: are you reliable?

Nationally, there has been a steady increase in the number of infants born with neonatal abstinence syndrome or drug withdrawal. Many of these infants remain in the hospital because their signs of withdrawal require pharmacologic management. The length of hospital stay can range from 1 week to several months depending on the severity of withdrawal. One way to decrease the length of stay and reduce the cost of care is to discharge the infant from the hospital sooner. To discharge infants sooner, their neonatal abstinence syndrome must be accurately assessed so that appropriate pharmacologic management can be administered. One way to increase the accuracy of assessing withdrawal signs is to implement an interobserver reliability protocol. This approach will allow healthcare professionals to gain consistency and accuracy in assessing infants for signs of withdrawal that may facilitate earlier discharge from the hospital.

Advances in infantile hypertrophic pyloric stenosis

Infantile hypertrophic pyloric stenosis (IHPS) is a common condition in infancy, characterized by an acquired narrowing of the pylorus, which requires surgery. These infants usually present with projectile, nonbilious vomiting, with a palpable 'olive' in the abdomen and sometimes a 'peristaltic wave' after being fed with formula or breast milk. Although IHPS is a common disorder, its etiology is largely unknown. Surgical intervention is the standard treatment, preoperative preparation, however is essential to optimal outcome. In this review, the latest advances in IHPS regarding epidemiology, etiology, diagnostics and treatment will be discussed.

Question of an infectious etiology or contribution to the pathogenesis of infantile hypertrophic pyloric stenosis

Infantile hypertrophic pyloric stenosis is a concerning cause of nonbilious vomiting in the neonatal population. Although a number of etiological theories exist, its exact cause remains nebulous. The question of an infectious etiology (or contribution) has been previously examined in case reports and case series, with recent support through suggestions of seasonality and familial aggregation with unclear inheritance patterns. The present review discusses the published literature regarding infectious etiologies of infantile hypertrophic pyloric stenosis. Furthermore, it attempts to demonstrate that newer research regarding an NOS1 genetic etiology does not exclude, but rather can be consistent with, an infectious etiology.

Neural stem cell therapies for enteric nervous system disorders

The enteric nervous system is vulnerable to a range of congenital and acquired disorders that disrupt the function of its neurons or lead to their loss. The resulting enteric neuropathies are some of the most challenging clinical conditions to manage. Neural stem cells offer the prospect of a cure given their potential ability to replenish missing or dysfunctional neurons. This article discusses diseases that might be targets for stem cell therapies and the barriers that could limit treatment application. We explore various sources of stem cells and the proof of concept for their use. The critical steps that remain to be addressed before these therapies can be used in patients are also discussed. Key milestones include the harvesting of neural stem cells from the human gut and the latest in vivo transplantation studies in animals. The tremendous progress in the field has brought experimental studies exploring the potential of stem cell therapies for the management of enteric neuropathies to the cusp of clinical application.

Hypertrophic pyloric stenosis in twins; genetic or environmental factors

The etiology of infantile hypertrophic pyloric stenosis (IHPS) remains obscure. Over 120 years after the condition has become a clinical entity the debate whether the cause of IHPS is genetic, environmental or both, has not yet reached a final conclusion. Herein, we present a pair of monozygotic male twins with IHPS together with a review of the literature. We aimed to support genetic pre-disposition in the epidemiology of IHPS, adding a twin data to the literature and to review the associated articles about the pathogenesis and inheritance patterns.

Proper development of the outer longitudinal smooth muscle of the mouse pylorus requires Nkx2-5 and Gata3

BACKGROUND & AIMS

Infantile hypertrophic pyloric stenosis is a common birth anomaly characterized by obstruction of the pyloric lumen. A genome-wide association study implicated NKX2-5, which encodes a transcription factor that is expressed in embryonic heart and pylorus, in the pathogenesis of infantile hypertrophic pyloric stenosis. However, the function of the NKX2-5 in pyloric smooth muscle development has not been examined directly. We investigated the pattern of Nkx2-5 during the course of murine pyloric sphincter development and examined coexpression of Nkx2-5 with Gata3 and Sox9-other transcription factors with pyloric-specific mesenchymal expression. We also assessed pyloric sphincter development in mice with disruption of Nkx2-5 or Gata3.

METHODS

We used immunofluorescence analysis to compare levels of NKX2-5, GATA3, and SOX9 in different regions of smooth muscle cells. Pyloric development was assessed in mice with conditional or germline deletion of Nkx2-5 or Gata3, respectively.

RESULTS

Gata3, Nkx2-5, and Sox9 are coexpressed in differentiating smooth muscle cells of a distinct fascicle of the pyloric outer longitudinal muscle. Expansion of this fascicle coincides with development of the pyloric sphincter. Disruption of Nkx2-5 or Gata3 causes severe hypoplasia of this fascicle and alters pyloric muscle shape. Although expression of Sox9 requires Nkx2-5 and Gata3, there is no apparent hierarchical relationship between Nkx2-5 and Gata3 during pyloric outer longitudinal muscle development.

CONCLUSIONS

Nkx2-5 and Gata3 are independently required for the development of a pyloric outer longitudinal muscle fascicle, which is required for pyloric sphincter morphogenesis in mice. These data indicate that regulatory changes that alter Nkx2-5 or Gata3 expression could contribute to pathogenesis of infantile hypertrophic pyloric stenosis.

Plasma lipids, genetic variants near APOA1, and the risk of infantile hypertrophic pyloric stenosis

IMPORTANCE

Infantile hypertrophic pyloric stenosis (IHPS) is a serious condition in which hypertrophy of the pyloric sphincter muscle layer leads to gastric outlet obstruction. Infantile hypertrophic pyloric stenosis shows strong familial aggregation and heritability, but knowledge about specific genetic risk variants is limited.

OBJECTIVES

To search the genome comprehensively for genetic associations with IHPS and validate findings in 3 independent sample sets.

DESIGN, SETTING, AND PARTICIPANTS

During stage 1, we used reference data from the 1000 Genomes Project for imputation into a genome-wide data set of 1001 Danish surgery-confirmed samples (cases diagnosed 1987-2008) and 2371 disease-free controls. In stage 2, the 5 most significantly associated loci were tested in independent case-control sample sets from Denmark (cases diagnosed 1983-2010), Sweden (cases diagnosed 1958-2011), and the United States (cases diagnosed 1998-2005), with a total of 1663 cases and 2315 controls.

MAIN OUTCOMES AND MEASURES

Association of genetic variation with the presence of infantile hypertrophic pyloric stenosis.

RESULTS

We found a new genome-wide significant locus for IHPS at chromosome 11q23.3. The single-nucleotide polymorphism (SNP) with the lowest P value at the locus, rs12721025 (odds ratio [OR], 1.59; 95% CI, 1.38-1.83; P = 1.9 × 10(-10)), is located 301 bases downstream of the apolipoprotein A-I (APOA1) gene and is correlated (r2 between 0.46 and 0.80) with SNPs previously found to be associated with levels of circulating cholesterol. For these SNPs, the cholesterol-lowering allele consistently was associated with increased risk of IHPS.

CONCLUSIONS AND RELEVANCE

This study identified a new genome-wide significant locus for IHPS. Characteristics of this locus suggest the possibility of an inverse relationship between levels of circulating cholesterol in neonates and IHPS risk, which warrants further investigation.

Tetrahydrobiopterin deficiency induces gastroparesis in newborn mice

Pyloric stenosis, the most common infant gastrointestinal disease, has no known etiology and clinically presents as abnormal gastric emptying with evidence of pyloric muscle hypertrophy. Whether abnormalities in gastric muscle contraction and/or relaxation have a role in this condition is poorly known, but gastroparesis is commonly observed in association with delayed gastric emptying in adults. Therefore, we evaluated the tetrahydrobiopterin (BH4)-deficient newborn mouse model of this disease (hph-1) and hypothesized that their gastric muscle properties are impaired, when compared with wild-type control animals. In vitro studies evaluating the age-dependent gastric fundus muscle contraction and relaxation potential were conducted. Compared with wild-type mice, the hph-1 stomach content/body weight ratio was significantly increased in newborn but not juvenile or adult animals, confirming abnormal gastric emptying. Gastric tissue neuronal nitric oxide synthase (nNOS) protein expression was upregulated in both newborn and adult hph-1 mice, but in the former there was evidence of enzyme uncoupling and higher tissue superoxide generation when compared with same age-matched animals. As opposed to the lack of strain differences in the U46619-induced force, the newborn hph-1 gastric muscle carbachol-induced contraction and nNOS-dependent relaxation were significantly reduced (P < 0.01). These group differences were not present in juvenile or adult mice. Preincubation with BH4 significantly enhanced the newborn hph-1, but not wild-type, gastric muscle contraction. In conclusion, changes compatible with gastroparesis are present in the newborn mouse model of pyloric stenosis. The role of BH4 deficiency and possibly associated gastroparesis in the pathogenesis of infantile pyloric stenosis warrants further investigation.

Development and developmental disorders of the enteric nervous system

The enteric nervous system (ENS) arises from neural crest-derived cells that migrate into and along the gut, leading to the formation of a complex network of neurons and glial cells that regulates motility, secretion and blood flow. This Review summarizes the progress made in the past 5 years in our understanding of ENS development, including the migratory pathways of neural crest-derived cells as they colonize the gut. The importance of interactions between neural crest-derived cells, between signalling pathways and between developmental processes (such as proliferation and migration) in ensuring the correct development of the ENS is also presented. The signalling pathways involved in ENS development that were determined using animal models are also described, as is the evidence for the involvement of the genes encoding these molecules in Hirschsprung disease-the best characterized paediatric enteric neuropathy. Finally, the aetiology and treatment of Hirschsprung disease in the clinic and the potential involvement of defects in ENS development in other paediatric motility disorders are outlined.