Novel chymotrypsin C (CTRC) variants from real-world genetic testing of pediatric chronic pancreatitis cases.

BACKGROUND: Chymotrypsin C (CTRC) protects the pancreas against unwanted intrapancreatic trypsin activity through degradation of trypsinogen. Loss-of-function CTRC variants increase the risk for chronic pancreatitis (CP). The aim of the present study was to characterize novel CTRC variants found during genetic testing of CP cases at a pediatric pancreatitis center. METHODS: We used next-generation sequencing to screen patients. We analyzed the functional effects of CTRC variants in HEK 293T cells and using purified enzymes. RESULTS: In 5 separate cases, we detected 5 novel heterozygous CTRC variants: c.407C>T (p.Thr136Ile), c.550G>A (p.Ala184Thr), c.627Cdup (p.Ser210Leufs∗?, where the naming indicates a frame shift with no stop codon), c.628T>C (p.Ser210Pro), and c.779A>G (p.Asp260Gly). Functional studies revealed that with the exception of p.Ser210Leufs∗?, the CTRC variants were secreted normally from transfected cells. Enzyme activity of purified variants p.Thr136Ile, p.Ala184Thr, and p.Asp260Gly was similar to that of wild-type CTRC, whereas variant p.Ser210Pro was inactive. The frame-shift variant p.Ser210Leufs∗? was not secreted but accumulated intracellularly, and induced endoplasmic reticulum stress, as judged by elevated mRNA levels of HSPA5 and DDIT3, and increased mRNA splicing of XBP1. CONCLUSIONS: CTRC variants p.Ser210Pro and p.Ser210Leufs∗? abolish CTRC function and should be classified as pathogenic. Mechanistically, variant p.Ser210Pro directly affects the amino acid at the bottom of the substrate-binding pocket while the frame-shift variant promotes misfolding and thereby blocks enzyme secretion. Importantly, 3 of the 5 novel CTRC variants proved to be benign, indicating that functional analysis is indispensable for reliable determination of pathogenicity and the correct interpretation of genetic test results.

Risk of chronic pancreatitis in carriers of the c.180C>T (p.Gly60=) CTRC variant: case-control studies and meta-analysis.

Chymotrypsin C (CTRC) is a digestive serine protease produced by the pancreas that regulates intrapancreatic trypsin activity and provides a defensive mechanism against chronic pancreatitis (CP). CTRC exerts its protective effect by promoting degradation of trypsinogen, the precursor to trypsin. Loss-of-function missense and microdeletion variants of CTRC are found in around 4% of CP cases and increase disease risk by approximately 3-7-fold. In addition, a commonly occurring synonymous CTRC variant c.180C>T (p.Gly60=) was reported to increase CP risk in various cohorts but a global analysis of its impact has been lacking. Here, we analyzed the frequency and effect size of variant c.180C>T in Hungarian and pan-European cohorts, and performed meta-analysis of the new and published genetic association data. When allele frequency was considered, meta-analysis revealed an overall frequency of 14.2% in patients and 8.7% in controls (allelic odds ratio (OR) 2.18, 95% confidence interval (CI) 1.72-2.75). When genotypes were examined, c.180TT homozygosity was observed in 3.9% of CP patients and in 1.2% of controls, and c.180CT heterozygosity was present in 22.9% of CP patients and in 15.5% of controls. Relative to the c.180CC genotype, the genotypic OR values were 5.29 (95% CI 2.63-10.64), and 1.94 (95% CI 1.57-2.38), respectively, indicating stronger CP risk in homozygous carriers. Finally, we obtained preliminary evidence that the variant is associated with reduced CTRC mRNA levels in the pancreas. Taken together, the results indicate that CTRC variant c.180C>T is a clinically relevant risk factor, and should be considered when genetic etiology of CP is investigated.

Faster recovery and bowel movement after early oral feeding compared to late oral feeding after upper GI tumor resections: a meta-analysis.

Background: There were more than 1 million new cases of stomach cancer concerning oesophageal cancer, there were more than 600,000 new cases of oesophageal cancer in 2020. After a successful resection in these cases, the role of early oral feeding (EOF) was questionable, due to the possibility of fatal anastomosis leakage. It is still debated whether EOF is more advantageous compared to late oral feeding. Our study aimed to compare the effect of early postoperative oral feeding and late oral feeding after upper gastrointestinal resections due to malignancy. Methods: Two authors performed an extensive search and selection of articles independently to identify randomized control trials (RCT) of the question of interest. Statistical analyses were performed including mean difference, odds ratio with 95% confidence intervals, statistical heterogeneity, and statistical publication bias, to identify potential significant differences. The Risk of Bias and the quality of evidence were estimated. Results: We identified 6 relevant RCTs, which included 703 patients. The appearance of the first gas (MD = -1.16; p = 0.009), first defecation (MD = -0.91; p < 0.001), and the length of hospitalization (MD = -1.92; p = 0.008) favored the EOF group. Numerous binary outcomes were defined, but significant difference was not verified in the case of anastomosis insufficiency (p = 0.98), pneumonia (p = 0.88), wound infection (p = 0.48), bleeding (p = 0.52), rehospitalization (p = 0.23), rehospitalization to the intensive care unit (ICU) (p = 0.46), gastrointestinal paresis (p = 0.66), ascites (p = 0.45). Conclusion: Early postoperative oral feeding, compared to late oral feeding has no risk of several possible postoperative morbidities after upper GI surgeries, but has several advantageous effects on a patient's recovery. Systematic Review Registration: identifier, CRD 42022302594.

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.

Risk of chronic pancreatitis in carriers of loss-of-function CTRC variants: A meta-analysis.

The digestive protease chymotrypsin C (CTRC) protects the pancreas against pancreatitis by degrading potentially harmful trypsinogen. Loss-of-function genetic variants in CTRC increase risk for chronic pancreatitis (CP) with variable effect size, as judged by the reported odds ratio (OR) values. Here, we performed a meta-analysis of published studies on four variants that alter the CTRC amino-acid sequence, are clinically relatively common (global carrier frequency in CP >1%), reproducibly showed association with CP and their loss of function phenotype was verified experimentally. We found strong enrichment of CTRC variants p.A73T, p.V235I, p.K247_R254del, and p.R245W in CP cases versus controls, yielding OR values of 6.5 (95% confidence interval (CI) 2.4-17.8), 4.5 (CI 2.2-9.1), 5.4 (CI 2.6-11.0), and 2.6 (CI 1.6-4.2), respectively. Subgroup analysis demonstrated disease association of variants p.K247_R254del and p.R245W in alcoholic CP with similar effect sizes as seen in the overall CP group. Homozygosity or compound heterozygosity were rare and seemed to be associated with higher risk. We also identified a so far unreported linkage disequilibrium between variant p.K247_R254del and the common c.180C>T (p.G60 =) haplotype. Taken together, the results indicate that heterozygous loss-of-function CTRC variants increase the risk for CP approximately 3-7-fold. This meta-analysis confirms the clinical significance of CTRC variants and provides further justification for the genetic screening of CP patients.

Common calcium-sensing receptor (CASR) gene variants do not modify risk for chronic pancreatitis in a Hungarian cohort.

The calcium-sensing receptor (CASR) is expressed in the pancreas where it might regulate calcium concentrations in pancreatic secretions. Two independent studies reported conflicting results claiming that commonly occurring missense variants of the CASR gene are risk factors for chronic pancreatitis (CP). Here, we attempted to replicate the association between CASR variants and CP. We analyzed 337 patients and 840 controls from the Hungarian National Pancreas Registry either by direct sequencing of exon 7 and the flanking noncoding regions or by TaqMan SNP genotyping assays. We identified two common missense variants, c.2956G>T (p.A986S), and c.2968A>G (p.R990G), three low-frequency variants, c.3031C>G (p.Q1011E), c.2610G>A (p.E870=) and c.∗60T>A, and 8 rare variants including the novel variant c.1895G>A (p.G632D). When allelic or genotype distributions were considered, none of the CASR variants associated with CP. Subgroup analysis of nonalcoholic versus alcoholic patients revealed no disease association either. Our results demonstrate that common CASR variants do not modify the risk for CP and should not be considered as genetic risk factors in the clinical setting.