Polymorphism screening in the cardiac K+ channel gene KCNA5
Polymorphism screening in the cardiac K+ channel gene KCNA5
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DOI：
10.1016/j.clpt.2004.10.008
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发表时间：
2005-03-01
影响因子：
6.7
通讯作者：
Roden, DM
中科院分区：
文献类型：
--
作者：
Simard, C;Drolet, B;Roden, DM
背景。先前已在长 QT 综合征疾病基因中鉴定出调节正常心脏电生理特征的常见脱氧核糖核酸多态性。在这项研究中，我们在 3 个种族中筛选了编码心脏钾通道 KCNA5（基础 I-Kur）的额外基因，并评估了所识别变异的功能后果。 方法。通过单链构象多态性分析和直接测序筛选编码区，并通过膜片钳转染的中国仓鼠卵巢细胞研究非同义变异。结果。 KCNA5 中发现了 5 个同义多态性和 6 个非同义多态性。这些多态性均不存在于超过 7% 的筛选等位基因或所有 3 个种族群体中。非同义 KCNA5 变体的表达显示门控正常。然而，2 个变体（P532L 和 R578K，均位于 C 末端）对原型抑制剂奎尼丁的阻断具有抵抗力；阻断 I-Kur 50% 所需的浓度 (IC50) 为 8.4 mumol/L（野生型），而 R578K 为 54 mumol/L，P532L 为 133 mumol/L（与野生型相比，两者 P < .0001）。结论：KCNA5 在其编码区中显示出很小的变异性。 C 端 KCNA5 变体表现出接近正常的门控，但对药物阻断具有显着的抵抗力；因此，这些药物基因组学研究已经确定了该区域作为药物通道敏感性调节剂的迄今为止未被认识到的作用。对 I-Kur 阻滞剂的耐药性可能是由基因决定的。
Background. Common deoxyribonucleic acid polymorphisms that modulate normal cardiac electrophysiologic characteristics have previously been identified in long QT syndrome disease genes. In this study we screened an additional gene encoding the cardiac potassium channel KCNA5 (underlying I-Kur) in 3 ethnic groups and evaluated the functional consequences of the variants identified.Methods. The coding region was screened by single-stranded conformational polymorphism analysis and direct sequencing, and nonsynonymous variants were studied by patch-clamping transfected Chinese hamster ovary cells.Results. Five synonymous and 6 nonsynonymous polymorphisms were found in KCNA5. None of these polymorphisms was present in greater than 7% of alleles screened or in all 3 ethnic groups. Expression of the nonsynonymous KCNA5 variants revealed normal gating. However, 2 variants (P532L and R578K, both in the C-terminus) were resistant to block by the prototypical inhibitor quinidine; the concentration required to block I-Kur by 50% (IC50) was 8.4 mumol/L for wild type versus 54 mumol/L for R578K and 133 mumol/L for P532L (both P < .0001, versus wild type).Conclusion: KCNA5 displays little variability in its coding region. C-terminal KCNA5 variants displayed near-normal gating but striking resistance to drug block; thus these pharmacogenomic studies have identified a heretofore-unappreciated role of this region as a modulator of channel sensitivity to drugs. Resistance to I-Kur blockers may be genetically determined.