Linkage of monogenic infantile hypertrophic pyloric stenosis to chromosome 16p12-p13 and evidence for genetic heterogeneity

Hypertrophic Pyloric Stenosis in Dizygotic Twins: Case Report

Infantile hypertrophic pyloric stenosis (IHPS) is a disorder encountered in infancy that is caused by hypertrophy of the musculature of the pylorus of the stomach. It may present as partial or complete gastric outlet obstruction. Multiple previous literatures have discussed the incidences and variability in the presentation of IHPS. However, there are very few reports of IHPS occurring in dizygotic twins, especially dizygotic twins of different sexes. Here we present a very rare case of dizygotic twins (a male and a female) affected with IHPS. With this study, we aim to identify the factors that lead to variability in severity and onset of symptoms in dizygotic twins of the opposite sex. We also aim to pay special attention to the etiology and mechanism of development of IHPS in dizygotic twins of the opposite sex.

Protein-elongating mutations in MYH11 are implicated in a dominantly inherited smooth muscle dysmotility syndrome with severe esophageal, gastric, and intestinal disease

Gastrointestinal motility disorders include a spectrum of mild to severe clinical phenotypes that are caused by smooth muscle dysfunction. We investigated the genetic etiology of severe esophageal, gastric, and colonic dysmotility in two unrelated families with autosomal dominant disease presentation. Using exome sequencing, we identified a 2 base pair insertion at the end of the myosin heavy chain 11 (MYH11) gene in all affected members of Family 1 [NM_001040113:c.5819_5820insCA(p.Gln1941Asnfs*91)] and a 1 base pair deletion at the same genetic locus in Proband 2 [NM_001040113:c.5819del(p.Pro1940Hisfs*91)]. Both variants are predicted to result in a similarly elongated protein product. Heterozygous dominant negative MYH11 pathogenic variants have been associated with thoracic aortic aneurysm and dissection while biallelic null alleles have been associated with megacystis microcolon intestinal hypoperistalsis syndrome. This report highlights heterozygous protein-elongating MYH11 variants affecting the SM2 isoforms of MYH11 as a cause for severe gastrointestinal dysmotility, and we hypothesize that the mechanistic pathogenesis of this disease, dominant hypercontractile loss-of-function, is distinct from those implicated in other diseases involving MYH11 dysfunction.

A novel missense mutation in the transcription factor FOXF1 cosegregating with infantile hypertrophic pyloric stenosis in the extended pedigree linked to IHPS5 on chromosome 16q24

BACKGROUND

The aim was to identify susceptibility alleles for infantile hypertrophic pyloric stenosis (IHPS) in a pedigree previously linked to IHPS5 on chromosome 16q24.

METHODS

We screened the positional and functional candidate gene FOXF1 by Sanger sequencing in a single affected individual. All family members for whom DNA was available were genotyped to determine cosegregation status of the putative causal variant. Immunofluorescence studies were performed to compare the cellular localization of wildtype and mutant form of the protein. Transcriptional activity was compared using a luciferase assay.

RESULTS

A single novel substitution in FOXF1 (c.416G>A) predicted to result in a missense mutation (R139Q) was shown to cosegregate with disease trait. It was not seen in 560 control chromosomes nor has it been reported in ExAC or ESP. The R139Q substitution affects a conserved arginine residue within the DNA-binding domain of FOXF1. The transcriptional activity of the mutant FOXF1 protein is significantly reduced in comparison to wild-type.

CONCLUSION

These results provide strong evidence that the R139Q substitution in FOXF1 causes IHPS in this family and imply a novel pathological pathway for the condition. They further support a role for FOXF1 in the regulation of embryonic and neonatal development of the gastro-intestinal tract.

Association between NKX2-5 rs29784 and infantile hypertrophic pyloric stenosis in Chinese Han population

PURPOSE

The aim of this study was to evaluate the association of three single nucleotide polymorphisms (SNPs, rs11712066 and rs573872 near MBNL1, rs29784 near NKX2-5) with infantile hypertrophic pyloric stenosis (IHPS) in Chinese Han population.

METHODS

A total of 47 family trios consisting of infants with IHPS and their healthy biological parents were recruited for this study. Genotypes were determined using direct sequencing. Transmission disequilibrium test (TDT) was performed for family-based association analysis.

RESULTS

Genotypic distributions of three SNPs in both groups (patients and proband's parents) were in conformity with Hardy-Weinberg equilibrium (P > 0.05). There were significant preferential transmission of A allele of rs29784 from the parents to affected offspring (TDT: x(2) = 5.444, P = 0.0196). However, other two polymorphism loci (rs11712066 and rs573872) were not significant susceptibility loci for IHPS in Chinese Han population.

CONCLUSIONS

We found that there was a significant association between rs29784 and IHPS.

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.

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.

Genetic contribution to motility disorders of the upper gastrointestinal tract

Motility disorders of the upper gastrointestinal tract encompass a wide range of different diseases. Esophageal achalasia and functional dyspepsia are representative disorders of impaired motility of the esophagus and stomach, respectively. In spite of their variable prevalence, what both diseases have in common is poor knowledge of their etiology and pathophysiology. There is some evidence showing that there is a genetic predisposition towards these diseases, especially for achalasia. Many authors have investigated the possible genes involved, stressing the autoimmune or the neurological hypothesis, but there is very little data available. Similarly, studies supporting a post-infective etiology, based on an altered immune response in susceptible individuals, need to be validated. Further association studies can help to explain this complex picture and find new therapeutic targets. The aim of this review is to summarize current knowledge of genetics in motility disorders of the upper gastrointestinal tract, addressing how genetics contributes to the development of achalasia and functional dyspepsia respectively.

Infantile hypertrophic pyloric stenosis in twins

Infantile hypertrophic pyloric stenosis (IHPS) is a common surgical cause of vomiting, which requires surgery in infant. There is the complete or partial obstruction of pylorus due to hypertrophy of circular muscle of the pylorus leading gastric outlet obstruction. The occurrence of IHPS in dizygotic twins is rarer and the theory of genetic origin alone does not explain it. Recent literature points to the association of bottle feeding in singletons to be a major aetiological factor for this condition. Here, we present a rare case of dizygotic twins who were bottle-fed and were affected with IHPS. We review the literature and focus on the question of whether this condition in twins supports a genetic or environmental origin of IHPS.

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.

Genome-wide linkage analysis in families with infantile hypertrophic pyloric stenosis indicates novel susceptibility loci

Infantile hypertrophic pyloric stenosis (IHPS) is a common cause of upper gastrointestinal obstruction during infancy. A multifactorial background of the disease is well established. Multiple susceptibility loci including the neuronal nitric oxide synthase (NOS1) gene have previously been linked to IHPS, but contradictory results of linkage studies in different materials indicate genetic heterogeneity. To identify IHPS susceptibility loci, we conducted a genome-wide linkage analysis in 37 Swedish families. In regions where the Swedish material showed most evidence in favor of linkage, 31 additional British IHPS families were analyzed. Evidence in favor of significant linkage was observed in the Swedish material to two loci on chromosome 2q24 (non-parametric linkage (NPL) =3.77) and 7p21 (NPL=4.55). In addition, evidence of suggestive linkage was found to two loci on chromosome 6p21 (NPL=2.97) and 12q24 (NPL=2.63). Extending the material with British samples did not enhance the level of significance. Regions with linkage harbor interesting candidate genes, such as glucagon-like peptide-2 (GLP-2 encoded by the glucagon gene GCG), NOS1, motilin (MLN) and neuropeptide Y (NPY). The coding exons for GLP-2, and NPY were screened for mutations with negative results. In conclusion, we could confirm suggestive linkage to the region harboring the NOS1 gene and detected additional novel susceptibility loci for IHPS.

No association between the SNPs (rs56134796; rs3824934; rs41302375) in the TRPC6 gene promoter and infantile hypertrophic pyloric stenosis in Chinese people

PURPOSE

Our aim is to verify the association of three Single nucleotide polymorphisms (SNPs) (-218A/G, -254C/G, -361A/T) in the promoter of TRPC6 in 168 sporadic cases with infantile hypertrophic pyloric stenosis (IHPS) and 164 controls in Chinese people.

METHODS

All participants were genotyped using polymerase chain reaction and direct sequencing. And the χ(2) value was calculated. A value of P less than 0.05 was considered statistically significant. We also got the P value of Hardy-Weinberg equilibrium test, and the value of P greater than 0.05 was assumed to be at Hardy-Weinberg equilibrium in this population.

RESULTS

The results tell us that there are no significant differences in the allele and genotype frequencies of all these three SNPs between the case and the control groups (P > 0.05).

CONCLUSION

These three TRPC6 SNPs have no association with the IHPS in Chinese people. However, we cannot deny that TRPC6 would be a susceptible gene with IHPS in Chinese people. May be other SNPs in TRPC6 would have some association with the IHPS in Chinese people. But in this study our results may be due to the fact that these SNPs are not the functional SNPs for the development of IHPS in Chinese people.

Infantile hypertrophic pyloric stenosis: An association in twins?

BACKGROUND

The etiology of infantile hypertrophic pyloric stenosis (IHPS) remains a mystery. Some suspected risk factors include birth rank, maternal age, sex, family history and monozygosity in twins. Various theories attempt to explain the etiology of IHPS. Scientific research suggests that enteric neuronal damage and nitric oxide synthase dysfunction may be implicated, but the consensus is that environmental modification must exist to account for the variability in its occurrence.

METHOD

Four cases of concordant occurrences of IHPS in twins were examined to determine the history and outcome of IHPS development in twins. Three sets were dizygotic and one was monozygotic. Of the eight infants, three were female, including the one monozygotic pair. In all four cases, a time lag existed between the development of symptomatic onset of IHPS in twin A and twin B. In one set, sonographic confirmation, performed because of IHPS diagnosis in the twin sibling, occurred concurrently with onset of vomiting, leading to early surgery before fluid and electrolyte imbalances developed.

CONCLUSIONS

Despite the lack of agreement as to whether the cause of IHPS is genetic, environmental or both, the high concordance rate seen in twins is indisputable. Thus, the empirical evidence provides credence to consider examining the asymptomatic co-twin when one of the twins presents with IHPS.

Infantile hypertrophic pyloric stenosis: evaluation of three positional candidate genes, TRPC1, TRPC5 and TRPC6, by association analysis and re-sequencing

Infantile hypertrophic pyloric stenosis (IHPS) is the most common inherited form of gastrointestinal obstruction in infancy with a striking male preponderance. Infants present with vomiting due to gastric outlet obstruction caused by hypertrophy of the smooth muscle of the pylorus. Two loci specific to extended pedigrees displaying autosomal dominant inheritance have been identified. A genome scan identified loci on chromosomes 11q14-q22 and Xq23-q24 which are predicted to be responsible for a subset of smaller families with IHPS demonstrating non-Mendelian inheritance. The two linked chromosomal regions both harbour functional candidate genes which are members of the canonical transient receptor potential (TRPC) family of ion channels. Both TRPC5 (Xq23-q24) and TRPC6 (11q14-q22) have a potential role in smooth muscle control and hypertrophy. Here, we report suggestive evidence for a third locus on chromosome 3q12-q25 (Zmax = 2.7, p < 0.004), a region which harbours a third TRPC gene, TRPC1. Fine mapping of all three genes using a tagSNP approach and re-sequencing identified a SNP in the promoter region of TRPC6 and a missense variant in exon 4 of TRPC6 which may be putative causal variants.

Lack of association between nNOS -84G>A polymorphism and risk of infantile hypertrophic pyloric stenosis in a Chinese population

BACKGROUND

Infantile hypertrophic pyloric stenosis (IHPS) is one of the most common gastrointestinal obstructions in the infancy requiring surgery. Reduced expression of neuronal nitric oxide synthase (nNOS), which plays an important role in the regulation of the human pyloric muscle, is thought to underlie IHPS. The role of nNOS in IHPS has been supported by the genetic association of a functional regulatory nNOS polymorphism (-84G>A) with IHPS in whites. We reasoned that the corroboration of this association in a population of different ethnic origin would prompt follow-up studies and further investigation of the IHPS pathology at molecular level. Thus, we attempted to reproduce the original findings in a Chinese population of comparable size in what would be the first genetic study on IHPS conducted in Chinese.

METHODS

nNOS -84G>A genotypes were analyzed in 56 patients and 86 controls by polymerase chain reaction and DNA sequencing. Logistic regression was used to compute odds ratios.

RESULTS

Our study could not corroborate the association previously reported. Although the frequency of the IHPS-associated allele (-84A) in controls (0.205) was similar to that reported for white controls, there was a dramatic difference in -84A frequencies between white and Chinese patients (0.198). Similarly, there was no difference in the nNOS -84G>A genotype distribution between patients and controls, even when the GA and AA genotypes were combined to compare GG genotype (odds ratio, 1.01; 95% confidence interval, 0.47-2.19).

CONCLUSIONS

Failure to replicate the initial finding does not detract from its validity, because genetic effects may differ across populations. Differences across populations in linkage disequilibrium and/or allele frequencies may contribute to this lack of replication. The role nNOS in IHPS awaits further investigation.

New insights into the pathogenesis of infantile pyloric stenosis

Infantile hypertrophic pyloric stenosis (IHPS) is the most common surgical cause of vomiting in infants. Despite numerous hypotheses, the aetiopathogenesis of IHPS is not fully understood. Genetic, extrinsic and hormonal factors have been implicated in the pathogenesis of the disease. Furthermore, abnormalities of various components of the pyloric muscle such as smooth muscle cells, growth factors, extracellular matrix elements, nerve and ganglion cells, synapses, nerve supporting cells, neurotransmitters and interstitial cells of Cajal have been reported. Recently, genetic studies have identified susceptibility loci for IHPS and molecular studies have concluded that smooth muscle cells are not properly innervated in IHPS.

Linkage of monogenic infantile hypertrophic pyloric stenosis to chromosome 16q24

Infantile hypertrophic pyloric stenosis (IHPS) is the most common inherited form of gastrointestinal obstruction in infancy. The disease is considered a paradigm for the sex-modified model of multifactorial inheritance and affects males four times more frequently than females. However, extended pedigrees consistent with autosomal dominant inheritance have been documented. We have analysed data from an extended IHPS family including eight affected individuals (five males and three females) and mapped the disease locus to chromosome 16q24 (LOD score=3.7) through an SNP-based genome wide scan. Fourteen additional multiplex pedigrees did not show evidence of linkage to this region, indicating locus heterogeneity.

Genome-wide high-density SNP-based linkage analysis of infantile hypertrophic pyloric stenosis identifies loci on chromosomes 11q14-q22 and Xq23

Infantile hypertrophic pyloric stenosis (IHPS) has an incidence of 1-8 per 1000 live births and is inherited as a complex sex-modified multifactorial trait with a striking male preponderance. Syndromic and monogenic forms exist, and two loci have been identified. Infants present with vomiting due to gastric-outlet obstruction caused by hypertrophy of the smooth muscle of the pylorus. A genome-wide SNP-based high-density linkage scan was carried out on 81 IHPS pedigrees. Nonparametric and parametric linkage analysis identified loci on chromosomes 11q14-q22 (Z(max) = 3.9, p < 0.0001; HLOD(max) = 3.4, alpha = 0.34) and Xq23 (Z(max) = 4.3, p < 0.00001; HLOD(max) = 4.8, alpha = 0.56). The two linked chromosomal regions each harbor functional candidate genes that are members of the canonical transient receptor potential (TRPC) family of ion channels and have a potential role in smooth-muscle control and hypertrophy.

Absence of motilin gene mutations in infantile hypertrophic pyloric stenosis

BACKGROUND

Erythromycin treatment before 2 weeks of age has been shown to increase the risk of infantile hypertrophic pyloric stenosis (IHPS) up to 10 times. Erythromycin is a motilin agonist, a hormone that induces gastrointestinal contractions. The purpose of this study was to investigate if mutations in the motilin gene (MLN) cause IHPS or if the V15A polymorphism in MLN is associated with the disease.

METHODS

The MLN was screened for mutations, and the V15A polymorphism was determined in a total of 57 patients with IHPS using polymerase chain reaction and DNA sequencing. The polymorphism genotype and allele frequencies among the patients were compared with 184 controls.

RESULTS

We detected 3 different, not previously reported, MLN sequence variants in 4 patients. One of these variants results in an amino acid exchange in the motilin signal peptide (A25G). All 3 detected sequence variants were also found in controls or were not inherited with the disease. We found no significant association between the V15A polymorphism and the disease.

CONCLUSIONS

We have excluded the MLN coding region as a major cause of IHPS. Future studies will evaluate the importance of this metabolic pathway in the pathogenesis of IHPS.