Functional impact of hERG variants S1021Qfs*98 and A228V associated with idiopathic ventricular fibrillation

Result code in IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F00216224%3A14110%2F25%3A00142658" target="_blank" >RIV/00216224:14110/25:00142658 - isvavai.cz</a>

Result on the web

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DOI - Digital Object Identifier

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Result language

angličtina

Original language name

Functional impact of hERG variants S1021Qfs*98 and A228V associated with idiopathic ventricular fibrillation

Original language description

Introduction and purpose: Human-ether-a-go-go-related-gene (hERG) encodes Kv11.1 protein which serves as the pore-forming subunit of the rapid delayed rectifier potassium (IKr) channel. Variants in the hERG gene may be then associated with various pathologies including arrhythmias, most often long QT syndrome type 2. The purpose of our study is to investigate the effect of two hERG variants identified in a patient suffering from idiopathic ventricular fibrillation (iVF), namely S1021Qfs*98 and A228V, on the function of Kv11.1. Methods: Functional analysis was performed using whole cell patch clamp technique in the voltage clamp mode at 37 °C. Chinese hamster ovary (CHO) cells were transfected with the plasmid carrying hERG without any mutation (wild type, WT) or hERG with the studied variants S1021Qfs*98 and A228V; five populations of CHO cells were harvested – (1) WT, (2) S1021Qfs*98, (3) A228V, (4) co-expressed S1021Qfs*98 and A228V 1:1 to simulate the situation in the heterozygous carrier (S1021Qfs*98/A228V), and (5) non-transfected cells as a negative control. Data were not normally distributed, thus, the median values are listed and statistical significance of the differences was tested using non-parametric tests (Mann-Whitney test and Kruskal-Wallis test with the Dunn ́s post-test). Results: In comparison with WT, no significant differences were observed in A228V, but the current was significantly decreased in S1021Qfs*98 and S1021Qfs*98/A228V (e.g. at +30 mV: 362.7 pA in WT, n = 17; 322.3 pA in A228V, n = 10, P &gt; 0.05 vs. WT; 134.3 pA in S1021Qfs*98, n = 17, P &lt; 0.01 vs. WT; 157.8 pA in S1021Qfs*98/A228V, n = 14, P &lt; 0.01 vs. WT). In S1021Qfs*98, no significant differences were identified in the voltage dependence of activation and inactivation as well as in the time course of activation and deactivation. The time constant of inactivation τinact was significantly longer in the case of S1021Qfs*98 (e.g. at 30 mV: 3,7 ms in WT, n = 14, vs. 7,2 ms in S1021Qfs*98; P &lt; 0.01, n = 10). Conclusions: We conclude that the S1021Qfs*98 variant resulted in a significant decrease of the hERG current by about 70 %, showing a loss-of-function effect that proves its pathogenic potential. Since no underlying changes in the channel gating responsible for this dysfunction have been identified, the impact of the variant on the channel expression is currently being studied. According to preliminary data, the A228V variant has shown a benign phenotype. In contrast, the co-transfected S1021Qfs*98/A228V channels lead to a dysfunction similar to that in the S1021Qfs*98 variant alone which suggests a dominant negative character of the S1021Qfs*98 variant.

Czech name

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Czech description

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Type

O - Miscellaneous

CEP classification

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OECD FORD branch

30201 - Cardiac and Cardiovascular systems

Project

<a href="/en/project/NU22-02-00348" target="_blank" >NU22-02-00348: Functional assessment of genetic variants in clinically “true” cases of idiopathic ventricular fibrillation: in vitro and in silico modelling to reveal the arrhythmogenic mechanism</a><br>

Continuities

P - Projekt vyzkumu a vyvoje financovany z verejnych zdroju (s odkazem do CEP)<br>S - Specificky vyzkum na vysokych skolach

Publication year

2025

Confidentiality

S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů