背景:心房颤动(AF)的家族性关联可能涉及与已知的心律失常机制相关的单基因变异;然而,全基因组关联研究经常揭示家族性和非家族性房颤的复杂遗传变异,使其难以与已知的致病机制联系起来。
方法:对4名患有房颤的兄弟姐妹的发现导致研究了一个家庭的47名成员。长期动态心电图监测(平均298小时)排除了沉默的AFWhole-exome测序,并根据当前的建议过滤并优先考虑索引病例共有的变体。使用膜片钳技术在表达人p.P1163H和/或天然Hcn4通道的中国仓鼠卵巢细胞中记录HCN4电流(IHCN4),并进行GATA5变体载体的拓扑相关结构域分析。
结果:临床研究又诊断出2例房颤。五个家族成员携带杂合p.P1163H,HCN4变体,14内含子20,61040536,G,GATA5罕见变体,和9携带两种变体(HCN4+GATA5)。6例AF病例中有5例(发病年龄在33-70岁之间)携带两种变体,其中一种仅携带GATA5变体。多变量分析显示,HCN4+GATA5变异的存在显著且独立地增加了房颤风险[OR=32.740(1.812-591.408)],而不是年龄。高血压或超重。功能测试显示杂合p.P1163H产生的IHcn4正常。拓扑关联域分析表明GATA5可以影响许多基因的表达,包括编码microRNA-1的那些。
结论:两种罕见基因变异的巧合与房颤独立相关,但是功能研究不允许假设所涉及的心律失常机制。
BACKGROUND: Familial association of atrial fibrillation (AF) can involve single gene variants related to known arrhythmogenic mechanisms; however, genome-wide association studies often disclose complex genetic variants in familial and nonfamilial AF, making it difficult to relate to known pathogenetic mechanisms.
METHODS: The finding of 4 siblings with AF led to studying 47 members of a family. Long-term Holter monitoring (average 298 hours) ruled out silent AF. Whole-exome sequencing was performed, and variants shared by the index cases were filtered and prioritised according to current recommendations.
HCN4 currents (IHCN4) were recorded in Chinese hamster ovary cells expressing human p.P1163H or native
HCN4 channels with the use of the patch-clamp technique, and topologically associating domain analyses of GATA5 variant were performed.
RESULTS: The clinical study diagnosed 2 more AF cases. Five family members carried the heterozygous p.P1163H
HCN4 variant, 14 carried the intronic 20,61040536,G,A GATA5 rare variant, and 9 carried both variants (
HCN4+GATA5). Five of the 6 AF cases (onset age ranging from 33 to 70 years) carried both variants and 1 carried the GATA5 variant alone. Multivariate analysis showed that the presence of
HCN4+GATA5 variants significantly increased AF risk (odds ratio 32.7, 95% confidence interval 1.8-591.4) independently from age, hypertension, and overweight. Functional testing showed that IHCN4 generated by heterozygous p.P1163H were normal. Topologically associating domain analysis suggested that GATA5 could affect the expression of many genes, including those encoding microRNA-1.
CONCLUSIONS: The coincidence of 2 rare gene variants was independently associated with AF, but functional studies do not allow the postulation of the arrhythmogenic mechanisms involved.