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A common polymorphism in KCNH2 (HERG) hastens cardiac repolarization

Item Type:Article
Title:A common polymorphism in KCNH2 (HERG) hastens cardiac repolarization
Creators Name:Bezzina, C.R. and Verkerk, A.O. and Busjahn, A. and Jeron, A. and Erdmann, J. and Koopmann, T.T. and Bhuiyan, Z.A. and Wilders, R. and Mannens, M.M.A.M. and Tan, H.L. and Luft, F.C. and Schunkert, H. and Wilde, A.A.M.
Abstract:Objective: Genetic variants of cardiac ion channels may influence cardiac repolarization. Thereby such variants may modulate the penetrance of primary electrical disorders, contribute to differences in susceptibility to drug-induced QT-prolongation between individuals, or contribute to rhythm disturbances in the context of structural heart disease. Since the current encoded by KCNH2 (HERG; IKr) is a primary determinant of repolarization, we conducted association studies between the respective alleles of the common amino acid-changing polymorphism at codon 897 (2690A>C; K897T) within HERG and rate-corrected QT interval (QTc). Methods and Results: Association analysis in Caucasian subjects (n=1030) revealed a significant association of this polymorphism with QTc (P=0.0025) with CC homozygotes having a significantly shorter QTc (388.5±2.9 ms) compared to AA homozygotes (398.5±0.9) and heterozygotes (AC, 397.2±1.2). The latter two genotypes were associated with comparable mean QTc's, suggesting that the 2690C-allele is recessive. After stratification by sex, the polymorphism was more predictive of QTc in females (P=0.0021), a finding that was replicated in a second population sample (n=352) from the same ethnic background (P=0.044). To assess whether this polymorphism could represent a 'functional' polymorphism, we compared the biophysical properties of K897- and T897-HERG channels by whole-cell voltage clamp. Compared to the K897 channel, the T897 channel displayed a shift of -7 mV in voltage dependence of activation and increased rates of current activation and deactivation. Conclusion: As confirmed in modeling studies, these changes are expected to shorten action potential duration by an increase in IKr. This recapitulates the shorter QTc in females homozygous for the 2690C-allele.
Keywords:K-Channel, Ion Channels, ECG, Epidemiology, Arrhythmias
Source:Cardiovascular Research
Page Range:27-36
Date:1 July 2003
Official Publication:https://doi.org/10.1016/S0008-6363(03)00342-0
PubMed:View item in PubMed

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