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

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.

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.

Hypertrophic Pyloric Stenosis

Hypertrophic pyloric stenosis is a common condition seen in the first 1 to 3 months after birth. Patients typically present with nonbilious projectile emesis after feeds that may result in hypokalemic, hypochloremic metabolic alkalosis. Although inability to tolerate feeds is frequently seen with self-limited conditions such as reflux, a low threshold to obtain an ultrasonographic image is important to prevent a delay in diagnosis. Although operative intervention is the treatment, it is imperative that patients are hydrated and serum electrolyte concentrations normalized before the induction of anesthesia. Laparoscopic pyloromyotomy is safe and effective. Postoperative emesis is normal, and reassurance to parents is appropriate. There is no significant long-term physiologic impairment from pyloric stenosis after successful surgical intervention.

Hypertrophic Pyloric Stenosis: 10 Years' Experience with Standard Open and Laparoscopic Approach

PURPOSE

Hypertrophic pyloric stenosis (HPS) is the most common cause of gastric obstruction in newborns. Extra-mucosal pyloromyotomy can be performed through a small laparotomy or laparoscopy. The aim of this study was to compare the two surgical techniques. We also analyzed the incidence of HPS in infants in the last 10 years in relation to the demographic trend of our province.

METHODS

We analyzed all the cases of HPS treated at our Unit between January 2010 and December 2019. The data were obtained from operating systems. Data about the demographic trends, in particular, the number of births and the population residing in the province of Verona from 2010 to 2019, were also retrieved.

RESULTS

During the study period, 60 patients were treated for HPS and met the inclusion criteria. Of these, 56 males and 4 females with an average age of 38±14 days at surgery were included. No differences were found in terms of the duration of surgery, post-operative complications, duration of hospitalization, and weight at the time of surgery. The only statistically significant data was the chlorine level in cases with and without post-operative vomiting (97±3.5 vs. 102±3.3 mmol/L, p<0.05). There was a lower incidence of HPS from 2014 to 2019; however, there was no significant evidence regarding the correlation between this and the reduced birth rate recorded in the province of Verona during the same period.

CONCLUSION

Although laparoscopic pyloromyotomy is a highly complex procedure, it is a feasible alternative to the classic open technique.

Integrating genetics with newborn metabolomics in infantile hypertrophic pyloric stenosis

INTRODUCTION

Infantile hypertrophic pyloric stenosis (IHPS) is caused by hypertrophy of the pyloric sphincter muscle.

OBJECTIVES

Since previous reports have implicated lipid metabolism, we aimed to (1) investigate associations between IHPS and a wide array of lipid-related metabolites in newborns, and (2) address whether detected differences in metabolite levels were likely to be driven by genetic differences between IHPS cases and controls or by differences in early life feeding patterns.

METHODS

We used population-based random selection of IHPS cases and controls born in Denmark between 1997 and 2014. We randomly took dried blood spots of newborns from 267 pairs of IHPS cases and controls matched by sex and day of birth. We used a mixed-effects linear regression model to evaluate associations between 148 metabolites and IHPS in a matched case-control design.

RESULTS

The phosphatidylcholine PC(38:4) showed significantly lower levels in IHPS cases (P = 4.68 × 10^-8) as did six other correlated metabolites (four phosphatidylcholines, acylcarnitine AC(2:0), and histidine). Associations were driven by 98 case-control pairs born before 2009, when median age at sampling was 6 days. No association was seen in 169 pairs born in 2009 or later, when median age at sampling was 2 days. More IHPS cases than controls had a diagnosis for neonatal difficulty in feeding at breast (P = 6.15 × 10^-3). Genetic variants known to be associated with PC(38:4) levels did not associate with IHPS.

CONCLUSIONS

We detected lower levels of certain metabolites in IHPS, possibly reflecting different feeding patterns in the first days of life.

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.

Genome-wide association studies of structural birth defects: A review and commentary

BACKGROUND

While there is strong evidence that genetic risk factors play an important role in the etiologies of structural birth defects, compared to other diseases, there have been relatively few genome-wide association studies (GWAS) of these conditions. We reviewed the current landscape of GWAS conducted for birth defects, noting novel insights, and future directions.

METHODS

This article reviews the literature with regard to GWAS of structural birth defects. Key defects included in this review include oral clefts, congenital heart defects (CHDs), biliary atresia, pyloric stenosis, hypospadias, craniosynostosis, and clubfoot. Additionally, other issues related to GWAS are considered, including the assessment of polygenic risk scores and issues related to genetic ancestry, as well as utilizing genome-wide single nucleotide polymorphism array data to evaluate gene-environment interactions and Mendelian randomization.

RESULTS

For some birth defects, including oral clefts and CHDs, several novel susceptibility loci have been identified and replicated through GWAS, including 8q24 for oral clefts, DGKK for hypospadias, and 4p16 for CHDs. Relatively common birth defects for which there are currently no published GWAS include neural tube defects, anotia/microtia, anophthalmia/microphthalmia, gastroschisis, and omphalocele.

CONCLUSIONS

Overall, GWAS have been successful in identifying several novel susceptibility genes and genomic regions for structural birth defects. These findings have provided new insights into the etiologies of these phenotypes. However, GWAS have been underutilized for understanding the genetic etiologies of several birth defects.

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.

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.

Contemporary management of pyloric stenosis

Hypertrophic pyloric stenosis is a common surgical cause of vomiting in infants. Following appropriate fluid resuscitation, the mainstay of treatment is pyloromyotomy. This article reviews the aetiology and pathophysiology of hypertrophic pyloric stenosis, its clinical presentation, the role of imaging, the preoperative and postoperative management, current surgical approaches and non-surgical treatment options. Contemporary postoperative feeding regimens, outcomes and complications are also discussed.

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.

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.

Use of macrolides in mother and child and risk of infantile hypertrophic pyloric stenosis: nationwide cohort study

OBJECTIVE

To assess the association between use of macrolide antibiotics in mothers and infants from pregnancy onset until 120 days after birth and infantile hypertrophic pyloric stenosis (IHPS).

DESIGN

Nationwide register based cohort study.

SETTING

Denmark, 1996-2011.

PARTICIPANTS

999,378 liveborn singletons and linked individual level information on macrolide prescriptions (maternal use during pregnancy, n=30,091; maternal use after birth, n=21,557; use in infants, n=6591), surgery for IHPS, and potential confounders.

MAIN OUTCOME MEASURES

Surgery for IHPS by three categories of macrolide use: in mothers during pregnancy, in mothers after birth, and in infants after birth.

RESULTS

880 infants developed IHPS (0.9 cases per 1000 births). Compared with infants with no use of macrolides, the adjusted rate ratio for IHPS in infants with use of macrolides during days 0 to 13 after birth was 29.8 (95% confidence interval 16.4 to 54.1) and during days 14 to 120 was 3.24 (1.20 to 8.74); the corresponding absolute risk differences were 24.4 (95% confidence interval 13.0 to 44.1) and 0.65 (0.06 to 2.21) cases per 1000 infants exposed to macrolides, respectively. The rate ratio for maternal use of macrolides for days 0 to 13 after birth was 3.49 (1.92 to 6.34) and for days 14 to 120 was 0.70 (0.26 to 1.90); the corresponding absolute risk differences were 2.15 (0.82 to 4.64) and -0.11 (-0.26 to 0.31). The rate ratios for maternal use of macrolides during pregnancy were 1.02 (0.65 to 1.59) for weeks 0 to 27 and 1.77 (0.95 to 3.31) for weeks 28 to birth; the corresponding absolute risk differences were 0.01 (-0.31 to 0.50) and 0.67 (-0.06 to 2.02).

CONCLUSIONS

Treatment of young infants with macrolide antibiotics was strongly associated with IHPS and should therefore only be administered if potential treatment benefits outweigh the risk. Maternal use of macrolides during the first two weeks after birth was also associated with an increased risk of IHPS. A possible association was also found with use during late pregnancy.