Departament de Ciències Mèdiques, Facultat de Medicina, Universitat de Girona, Girona, Spain; Cardiovascular Genetics Center, Institut d'Investigació Biomèdica de Girona Dr. Josep Trueta, Girona, Spain.
Cardiovascular Genetics Center, Institut d'Investigació Biomèdica de Girona Dr. Josep Trueta, Girona, Spain.
Heart Rhythm. 2024 Mar;21(3):331-339. doi: 10.1016/j.hrthm.2023.11.019. Epub 2023 Nov 24.
Brugada syndrome (BrS) is an inherited cardiac arrhythmogenic disease that predisposes patients to sudden cardiac death. It is associated with mutations in SCN5A, which encodes the cardiac sodium channel alpha subunit (Na1.5). BrS-related mutations have incomplete penetrance and variable expressivity within families.
The purpose of this study was to determine the role of patient-specific genetic background on the cellular and clinical phenotype among carriers of Na1.5_p.V1525M.
We studied sodium currents from patient-specific human-induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) and heterologously transfected human embryonic kidney (HEK) tsA201 cells using the whole-cell patch-clamp technique. We determined gene and protein expression by quantitative polymerase chain reaction, RNA sequencing, and western blot and performed a genetic panel for arrhythmogenic diseases.
Our results showed a large reduction in I density in hiPSC-CM derived from 2 V1525M single nucleotide variant (SNV) carriers compared with hiPSC-CM derived from a noncarrier, suggesting a dominant-negative effect of the Na1.5_p.V1525M channel. I was not affected in hiPSC-CMs derived from a V1525M SNV carrier who also carries the Na1.5_p.H558R polymorphism. Heterozygous expression of V1525M in HEK-293T cells produced a loss of I function, not observed when this variant was expressed together with H558R. In addition, the antiarrhythmic drug mexiletine rescued I function in hiPSC-CM. SCN5A expression was increased in the V1525M carrier who also expresses Na1.5_p.H558R.
Our results in patient-specific hiPSC-CM point to a dominant-negative effect of Na1.5_p.V1525M, which can be reverted by the presence of Na1.5_p.H558R. Overall, our data points to a role of patient-specific genetic background as a determinant for incomplete penetrance in BrS.
Brugada 综合征（BrS）是一种遗传性心律失常疾病，使患者易发生心源性猝死。它与编码心脏钠离子通道 α 亚基（Na1.5）的 SCN5A 基因突变有关。BrS 相关突变在家族内存在不完全外显率和可变表达性。
本研究旨在确定 Na1.5_p.V1525M 携带者的个体遗传背景对细胞和临床表型的作用。
我们使用全细胞膜片钳技术研究了来自患者特异性诱导多能干细胞衍生的心肌细胞（hiPSC-CMs）和异源转染的人胚肾（HEK）tsA201 细胞的钠离子电流。我们通过定量聚合酶链反应、RNA 测序和 Western blot 确定基因和蛋白表达，并进行心律失常疾病的遗传panel 检测。
我们的结果表明，与非携带者相比，来自 2 个 V1525M 单核苷酸变异（SNV）携带者的 hiPSC-CM 中 I 密度显著降低，提示 Na1.5_p.V1525M 通道具有显性负效应。在携带 Na1.5_p.H558R 多态性的 V1525M SNV 携带者的 hiPSC-CM 中，I 不受影响。V1525M 在 HEK-293T 细胞中的杂合表达导致 I 功能丧失，而当该变体与 H558R 一起表达时则不会观察到这种情况。此外，抗心律失常药物美西律可挽救 hiPSC-CM 中的 I 功能。在同时表达 Na1.5_p.H558R 的 V1525M 携带者中，SCN5A 表达增加。
我们在患者特异性 hiPSC-CM 中的结果表明，Na1.5_p.V1525M 具有显性负效应，而 Na1.5_p.H558R 的存在可使其逆转。总的来说，我们的数据表明个体遗传背景是 BrS 不完全外显率的决定因素。
