The CFTR gene variants in Japanese children with idiopathic pancreatitis

A comprehensive review of cystic fibrosis in Africa and Asia

Cystic fibrosis (CF) was earlier thought to be a disease prevalent in the West among Caucasians. However, quite a number of recent studies have uncovered CF cases outside of this region, and reported hundreds of unique and novel variant forms of CFTR. Here, we discuss the evidence of CF in parts of the world earlier considered to be rare; Africa, and Asia. This review also highlighted the CFTR mutation variations and new mutations discovered in these regions. This discovery implies that the CF data from these regions were earlier underestimated. The inadequate awareness of the disease in these regions might have contributed towards the poor diagnostic facilities, under-diagnosis or/and under-reporting, and the lack of CF associated health policies. Overall, these regions have a high rate of infant, childhood and early adulthood mortality due to CF. Therefore, there is a need for a thorough investigation of CF prevalence and to identify unique and novel variant mutations within these regions in order to formulate intervention plans, create awareness, develop mutation specific screening kits and therapies to keep CF mortality at bay.

The Coexistence of TRPV6 Variants With Other Pancreatitis-Associated Genes Affects Pediatric-Onset Pancreatitis

OBJECTIVES

Recently, a genetic risk for chronic pancreatitis (CP) was found to be conferred by pathogenic variants in the transient receptor potential cation channel, subfamily V, member 6 ( TRPV6 ). Interestingly, 20%-57% of patients with functionally defective TRPV6 variants have other susceptibility genes such as cationic trypsinogen, serine protease inhibitor Kazal type 1, chymotrypsin C, cystic fibrosis transmembrane conductance regulator, and carboxypeptidase A1. In this study, we focused on pediatric patients with acute recurrent pancreatitis or CP with at least 1 variant in these 5 genes and investigated the presence of coexisting TRPV6 mutations.

METHODS

Ninety Japanese pediatric patients (median age at first onset, 8.0 years) who had at least 1 variant of these 5 genes were enrolled in this study. DNA samples were extracted for analysis from peripheral blood leukocytes. Coding regions of TRPV6 were screened by Sanger sequencing.

RESULTS

Regardless of functional defects or non-defects in TRPV6 variants, 14 of the 90 patients (15.6%) were trans-heterozygous for TRPV6 variants [p.A18S (n = 3), p.C197R (n = 3), p.I223T (n = 3), p.D324N (n = 4), p.M418V (n = 3), p.V540F (n = 1), p.A606T (n = 1), and p.M721T (n = 3)] and the 5 susceptibility genes noted above. Of these variants, p.D324N, p.V540F, and p.A606T are associated with pancreatitis. Three patients had the ancestral haplotype [p.C197R + p.M418V + p.M721T].

CONCLUSIONS

Overall, 4 of 90 patients (4.4%) had the coexistence of clearly pathogenic TRPV6 variants with pancreatitis-associated variants. The cumulative accumulation of these genetic factors may contribute to the development of pancreatitis at a young age.

Bicarbonate defective CFTR variants increase risk for chronic pancreatitis: A meta-analysis

INTRODUCTION

Cystic fibrosis transmembrane conductance regulator (CFTR) plays a central role in pancreatic ductal fluid secretion by mediating Cl- and HCO3- ion transport across the apical membrane. Severe CFTR mutations that diminish chloride conductance cause cystic fibrosis (CF) if both alleles are affected, whereas heterozygous carrier status increases risk for chronic pancreatitis (CP). It has been proposed that a subset of CFTR variants characterized by a selective bicarbonate conductance defect (CFTRBD) may be associated with CP but not CF. However, a rigorous genetic analysis of the presumed association has been lacking.

AIMS

To investigate the role of heterozygous CFTRBD variants in CP by meta-analysis of published case-control studies.

MATERIALS AND METHODS

A systematic search was conducted in the MEDLINE, Embase, Scopus, and CENTRAL databases for published studies that reported the CFTRBD variants p.R74Q, p.R75Q, p.R117H, p.R170H, p.L967S, p.L997F, p.D1152H, p.S1235R, and p.D1270N in CP patients and controls.

RESULTS

Twenty-two studies were eligible for quantitative synthesis. Combined analysis of the 9 CFTRBD variants indicated enrichment in CP patients versus controls (OR = 2.31, 95% CI = 1.17-4.56). Individual analysis of CFTRBD variants revealed no association of p.R75Q with CP (OR = 1.12, 95% CI = 0.89-1.40), whereas variants p.R117H and p.L967S were significantly overrepresented in cases relative to controls (OR = 3.16, 95% CI = 1.94-5.14, and OR = 3.88, 95% CI = 1.32-11.47, respectively). The remaining 6 low-frequency variants gave inconclusive results when analyzed individually, however, their pooled analysis indicated association with CP (OR = 2.08, 95% CI = 1.38-3.13).

CONCLUSION

Heterozygous CFTRBD variants, with the exception of p.R75Q, increase CP risk about 2-4-fold.

Comparison of idiopathic recurrent acute pancreatitis [IRAP] and recurrent acute pancreatitis with genetic mutations

BACKGROUND

Idiopathic recurrent acute pancreatitis (IRAP) describes frequent episodes of pancreatitis without an etiology found using current testing. We compared the natural history of IRAP with recurrent acute pancreatitis with genetic mutations.

METHODS

Retrospective cohort of patients with recurrent acute pancreatitis (≥2 episodes) and negative conventional testing. All patients had ≥1 episode after cholecystectomy and completed genetic testing. Primary outcomes were chronic pancreatitis incidence, pancreatic cancer, and mortality. Secondary outcomes included opioid and ERCP utilization.

RESULTS

128 patients met criteria for presumed IRAP. 35 patients met criteria for true IRAP. 12 patients had recurrent acute pancreatitis with gene mutations. Chronic pancreatitis developed in 27 (77.1%) IRAP patients over a median of 6 years. Chronic pancreatitis incidence was similar in IRAP and CFTR mutation carriers; but developed later in SPINK1 carriers. No patients developed pancreatic cancer or died from pancreatic-related causes. Patients were frequently treated with oral opioids and ERCP, without significant differences within or between groups.

CONCLUSION

IRAP and pancreatitis in mutation carriers is associated with chronic pancreatitis. Important differences in natural history were observed, but no association was found with cancer or pancreas-related mortality. Efforts to understand the genetic contributions to IRAP, minimize opioids and unnecessary ERCPs are encouraged.

Genetics of agenesis/hypoplasia of the uterus and vagina: narrowing down the number of candidate genes for Mayer-Rokitansky-Küster-Hauser Syndrome

PURPOSE

Mayer-Rokitansky-Küster-Hauser (MRKH) syndrome consists of congenital absence of the uterus and vagina and is often associated with renal, skeletal, cardiac, and auditory defects. The genetic basis is largely unknown except for rare variants in several genes. Many candidate genes have been suggested by mouse models and human studies. The purpose of this study was to narrow down the number of candidate genes.

METHODS

Whole exome sequencing was performed on 111 unrelated individuals with MRKH; variant analysis focused on 72 genes suggested by mouse models, human studies of physiological candidates, or located near translocation breakpoints in t(3;16). Candidate variants (CV) predicted to be deleterious were confirmed by Sanger sequencing.

RESULTS

Sanger sequencing verified 54 heterozygous CV from genes identified through mouse (13 CV in 6 genes), human (22 CV in seven genes), and translocation breakpoint (19 CV in 11 genes) studies. Twelve patients had ≥ 2 CVs, including four patients with two variants in the same gene. One likely digenic combination of LAMC1 and MMP14 was identified.

CONCLUSION

We narrowed 72 candidate genes to 10 genes that appear more likely implicated. These candidate genes will require further investigation to elucidate their role in the development of MRKH.

Pulmonary Manifestations of Gastrointestinal, Pancreatic, and Liver Diseases in Children

Pulmonary manifestations of gastrointestinal (GI) diseases are often subtle, and underlying disease may precede overt symptoms. A high index of suspicion and a low threshold for consultation with a pediatric pulmonologist is warranted in common GI conditions. This article outlines the pulmonary manifestations of different GI, pancreatic, and liver diseases in children, including gastroesophageal reflux disease, inflammatory bowel disease, pancreatitis, alpha1-antitrypsin deficiency, nonalcoholic fatty liver disease, and complications of chronic liver disease (hepatopulmonary syndrome and portopulmonary hypertension).

Pancreatic complications in children with cystic fibrosis

PURPOSE OF REVIEW

The pancreas is highly affected in cystic fibrosis, with complications occurring early in childhood. This review highlights recent research in exocrine pancreatic function in the era of cystic fibrosis transmembrane conductance regulator (CFTR) modulator therapies and discusses how these are affecting pancreatitis and exocrine pancreatic insufficiency (EPI) in children. Additionally, new research into exocrine--endocrine interactions sheds light on how CFTR dysfunction in ductal cells may affect beta cells.

RECENT FINDINGS

Ivacaftor has disproved the hypothesis that EPI in children with cystic fibrosis is irreversible. Improvements in pancreatic function have increased pancreatitis episodes in some children and reduced them in others. Imaging advances are providing complementary methods for exocrine pancreatic function testing. New research into the interplay between the exocrine and endocrine components of the pancreas are elucidating the intertwined and complex relationship between the exocrine and endocrine pancreas.

SUMMARY

Pancreatic complications contribute to the morbidity and mortality of children with cystic fibrosis. Increasing use of highly effective CFTR modulators will not only abrogate these but will also advance our understanding of pancreatic pathophysiology in cystic fibrosis. New frontiers into pancreatic gene therapy and exocrine--endocrine research will help provide new therapeutic opportunities for pancreatitis, EPI, and diabetes in cystic fibrosis.