Rationale: Genome-wide association studies previously identified an association of rs9388451 at chromosome 6q22.3 (near HEY2) with Brugada syndrome. The causal gene and underlying mechanism remain unresolved.

Objective: We used an integrative approach entailing transcriptomic studies in human hearts and electrophysiological studies in Hey2^+/− (Hey2 heterozygous knockout) mice to dissect the underpinnings of the 6q22.31 association with Brugada syndrome.

Methods and Results: We queried expression quantitative trait locus data acquired in 190 human left ventricular samples from the genotype-tissue expression consortium for cis-expression quantitative trait locus effects of rs9388451, which revealed an association between Brugada syndrome risk allele dosage and HEY2 expression (β=+0.159; P=0.0036). In the same transcriptomic data, we conducted genome-wide coexpression analysis for HEY2, which uncovered KCNIP2, encoding the β-subunit of the channel underlying the transient outward current (I_to), as the transcript most robustly correlating with HEY2 expression (β=+1.47; P=2×10⁻³⁴). Transcript abundance of Hey2 and the I_to subunits Kcnip2 and Kcnd2, assessed by quantitative reverse transcription–polymerase chain reaction, was higher in subepicardium versus subendocardium in both left and right ventricles, with lower levels in Hey2^+/− mice compared with wild type. Surface ECG measurements showed less prominent J waves in Hey2^+/− mice compared with wild-type. In wild-type mice, patch-clamp electrophysiological studies on cardiomyocytes from right ventricle demonstrated a shorter action potential duration and a lower V_max in subepicardium compared with subendocardium cardiomyocytes, which was paralleled by a higher I_to and a lower sodium current (I_Na) density in subepicardium versus subendocardium. These transmural differences were diminished in Hey2^+/− mice because of changes in subepicardial cardiomyocytes.

Conclusions: This study uncovers a role of HEY2 in the normal transmural electrophysiological gradient in the ventricle and provides compelling evidence that genetic variation at 6q22.31 (rs9388451) is associated with Brugada syndrome through a HEY2-dependent alteration of ion channel expression across the cardiac ventricular wall.

基本原理：全基因组关联研究先前确定了6938号染色体上的rs9388451与Brugada综合征相关（在HEY2附近）。因果基因和潜在机制仍未解决。

目的：我们采用整合方法，在人类心脏中进行转录组学研究，并在Hey2 ^+/-（ Hey2杂合敲除）小鼠中进行电生理研究，以剖析6q22.31与Brugada综合征相关的基础。

方法和结果：我们查询了从基因型组织表达协会的190个人左心室样本中获得的表达定量性状基因座数据，以了解rs9388451的顺式表达定量性状基因座效应，这揭示了Brugada综合征风险等位基因剂量与HEY2表达之间存在关联（ β＝ + 0.159； P＝ 0.0036）。在相同的转录组数据中，我们对HEY2进行了全基因组范围的共表达分析，该发现未发现KCNIP2，其编码作为瞬时外向电流（ I_至）的通道的β-亚基，因为该转录本与HEY2的表达最密切相关（β= +1.47; P= 2×10 ^-34）。通过定量逆转录-聚合酶链反应评估，Hey2和I_到Kcnip2和Kcnd2亚基的转录丰度在左心室和右心室中在心外膜下层比在心内膜下层高，而在Hey2 ^+/-小鼠中与野生型相比较低。表面ECG测量显示，与野生型相比，Hey2 ^+/-小鼠的J波不那么突出。在野生型小鼠中，对右心室的心肌细胞进行膜片钳电生理研究表明，其动作电位持续时间较短，V _max较低在外膜与心内膜心肌细胞，将其通过一个更高并联相比我_到和下部钠电流（我_的Na）密度在外膜与心内膜下。由于心外膜下心肌细胞的变化，这些透壁差异在Hey2 ^+/-小鼠中减少了。

结论：这项研究揭示了HEY2在心室正常的透壁电生理梯度中的作用，并提供了令人信服的证据，表明6q22.31（rs9388451）的遗传变异是通过HEY2依赖的整个心脏离子通道表达的改变与Brugada综合征相关的心室壁。