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.

Unmasking Risky Habits: Identifying and Predicting Problem Gamblers Through Machine Learning Techniques.

The use of machine learning techniques to identify problem gamblers has been widely established. However, existing methods often rely on self-reported labeling, such as temporary self-exclusion or account closure. In this study, we propose a novel approach that combines two documented methods. First we create labels for problem gamblers in an unsupervised manner. Subsequently, we develop prediction models to identify these users in real-time. The methods presented in this study offer useful insights that can be leveraged to implement interventions aimed at guiding or discouraging players from engaging in disordered gambling behaviors. This has potential implications for promoting responsible gambling and fostering healthier player habits.

Novel p.G250A Mutation Associated with Chronic Pancreatitis Highlights Misfolding-Prone Region in Carboxypeptidase A1 (CPA1).

Inborn mutations in the digestive protease carboxypeptidase A1 (CPA1) gene may be associated with hereditary and idiopathic chronic pancreatitis (CP). Pathogenic mutations, such as p.N256K, cause intracellular retention and reduced secretion of CPA1, accompanied by endoplasmic reticulum (ER) stress, suggesting that mutation-induced misfolding underlies the phenotype. Here, we report the novel p.G250A CPA1 mutation found in a young patient with CP. Functional properties of the p.G250A mutation were identical to those of the p.N256K mutation, confirming its pathogenic nature. We noted that both mutations are in a catalytically important loop of CPA1 that is stabilized by the Cys248-Cys271 disulfide bond. Mutation of either or both Cys residues to Ala resulted in misfolding, as judged by the loss of CPA1 secretion and intracellular retention. We re-analyzed seven previously reported CPA1 mutations that affect this loop and found that all exhibited reduced secretion and caused ER stress of varying degrees. The magnitude of ER stress was proportional to the secretion defect. Replacing the naturally occurring mutations with Ala (e.g., p.V251A for p.V251M) restored secretion, with the notable exception of p.N256A. We conclude that the disulfide-stabilized loop of CPA1 is prone to mutation-induced misfolding, in most cases due to the disruptive nature of the newly introduced side chain. We propose that disease-causing CPA1 mutations exhibit abolished or markedly reduced secretion with pronounced ER stress, whereas CPA1 mutations with milder misfolding phenotypes may be associated with lower disease risk or may not be pathogenic at all.

Static and dynamic shear viscosity of a single-layer complex plasma.

The static and dynamic (complex) shear viscosity of a single-layer dusty plasma is measured by applying, respectively, a stationary and a periodically modulated shear stress, induced by the light pressure of manipulating laser beams. Under static conditions we observe a decrease of the viscosity with increasing shear rate, the so-called shear-thinning behavior. Under oscillating shear both the magnitude and the ratio of the dissipative and elastic contributions to the complex viscosity show strong frequency dependence, as the system changes from viscous to elastic in nature with increasing excitation frequency. Accompanying molecular dynamics simulations explain and support the experimental observations.