The Cardiovascular Center, Department of Cardiology, Interventional Medical Center, Guangdong Provincial Key Laboratory of Biomedical Imaging and Guangdong Provincial Engineering Research Center of Molecular Imaging, The Fifth Affiliated Hospital, Sun Yat-sen University, Zhuhai, China.
Guangdong Provincial People's Hospital, Guangdong Academy of Medical Sciences, Guangdong Cardiovascular Institute, Guangzhou, China.
Mol Genet Genomic Med. 2021 May;9(5):e1613. doi: 10.1002/mgg3.1613. Epub 2021 Mar 25.
We examined the genetic background of a Chinese Han family in which some members presented with complex arrhythmias including sick sinus syndrome, progressive conduction block, atrial fibrillation, atrial standstill and Brugada syndrome. The possible underlying mechanism associated with the genetic mutation was explored.
Targeted capture sequencing was conducted in the probands in the coding and splicing regions of genes implicated in inherited arrhythmias. Stable cell lines overexpressing wild type (WT) or mutant SCN5A were generated in HEK293T cells. Whole-cell recording was performed to evaluate the functional changes in sodium channels.
The rare heterozygous linkage mutations, SCN5A R965C and R1309H, were found in these patients with complex familial arrhythmias. Compared to WT, R965C or R1309H, the peak current of sodium channel was dramatically reduced in HEK293T cell with linkage R965C-R1309H mutation when testing potentials ranging from -45 to 15 mV. Notably, the maximum peak current of sodium channels with R1309H and linkage R965C-R1309H displayed significant decreases of 31.5% and 73.34%, respectively, compared to WT. Additionally, compared to R965C or R1309H alone, the linkage mutation R965C-R1309H demonstrated not only a more obvious depolarisation-shifted activation and hyperpolarisation-shifted inactivation, but also a more significant alteration in the time constant, V and the slope factor of activation and inactivation.
The linkage mutation SCN5A R965C-R1309H led to a more dramatically reduced current density, as well as more significant depolarisation-shifted activation and hyperpolarisation-shifted inactivation in sodium channels than R965C or R1309H alone, which potentially explain this complex familial arrhythmia syndrome.
我们研究了一个中国汉族家族的遗传背景，该家族的一些成员表现出复杂的心律失常，包括窦性心动过缓综合征、进行性传导阻滞、心房颤动、心房停搏和 Brugada 综合征。探讨了与遗传突变相关的潜在机制。
对先证者编码区和剪接区与遗传性心律失常相关的基因进行靶向捕获测序。在 HEK293T 细胞中生成野生型（WT）或突变 SCN5A 的稳定过表达细胞系。进行全细胞记录以评估钠通道功能变化。
在这些具有复杂家族性心律失常的患者中发现了罕见的杂合连锁突变 SCN5A R965C 和 R1309H。与 WT 相比，当测试电位范围从 -45 到 15 mV 时，具有连锁 R965C-R1309H 突变的 HEK293T 细胞中钠通道的峰值电流明显减少。值得注意的是，与 WT 相比，R1309H 和连锁 R965C-R1309H 的钠通道最大峰值电流分别显著降低了 31.5%和 73.34%。此外，与 R965C 或 R1309H 单独相比，连锁突变 R965C-R1309H 不仅表现出更明显的去极化移激活和超极化移失活，而且对激活和失活的时间常数、V 和斜率因子的改变也更为显著。
与 R965C 或 R1309H 单独相比，SCN5A R965C-R1309H 连锁突变导致钠通道的电流密度降低更为明显，以及去极化移激活和超极化移失活更为显著，这可能解释了这种复杂的家族性心律失常综合征。
