Characterization of a Chinese KCNQ1 mutation （R259H） that shortens repolarization and causes short QT syndrome 2  

作　　者：Zhi-Juan WU Yun HUANG Yi-Cheng FU Xiao-Jing ZHAO Chao ZHU Yu ZHANG Bin XU Qing-Lei ZHU Yang LI 

机构地区：[1]Department of Cardiology, Chinese PLA General Hospital, 28 Fuxing Road, Beijing, China [2]Department of Gerontology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China

出　　处：《Journal of Geriatric Cardiology》2015年第4期394-401,共8页老年心脏病学杂志（英文版）

基　　金：grants obtained from the National Natural Science Foundation of China （No.： 81170177, 81030002） and science and Technology De- partment of Gansu Province Project （145RJZ104）.

摘　　要：Objectives To evaluate the association between a KCNQ 1 mutation, R259H, and short QT syndrome （SQTS） and to explore the elec- trophysiological mechanisms underlying their association. Methods We performed genetic screening of SQTS genes in 25 probands and their family members （63 patients）. We used direct sequencing to screen the exons and intron-exon boundaries of candidate genes that en- code ion channels which contribute to the repolarization of the ventricular action potential, including KCNQI, KCNH2, KCNE1, KCNE2, KCNJ2, CACNAlc, CACNB2b and CACNA2D1. In one of the 25 SQTS probands screened, we discovered a KCNQ1 mutation, R259H. We cloned R259H and transiently expressed it in HEK-293 cells; then, currents were recorded using whole cell patch clamp techniques. Results R259H-KCNQ 1 showed significantly increased current density, which was approximately 3-fold larger than that of wild type （WT） after a depolarizing pulse at 1 s. The steady state voltage dependence of the activation and inactivation did not show significant differences between the WT and R259H mutation （P 〉 0.05）, whereas the time constant of deactivation was markedly prolonged in the mutant compared with the WT in terms of the test potentials, which indicated that the deactivation of R259H was markedly slower than that of the WT. These results suggested that the R259H mutation can effectively increase the slowly activated delayed rectifier potassium current （Irs） in phase 3 of the cardiac action potential, which may be an infrequent cause of QT interval shortening. Conclusions R259H is a gain-of-function muta- tion of the KCNQ1 channel that is responsible for SQTS2. This is the first time that the R259H mutation was detected in Chinese people.

关 键 词：Ion channel KCNQ1 gene MUTATION Short QT syndrome Slowly activated delayed rectifier potassium current 

分 类 号：Q463[生物学—生理学] S826.2[农业科学—畜牧学]