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 s...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.展开更多
Objective To compare the distribution ofKCNJll polymorphisms between elderly Chinese population with and without hypertension. Methods We examined the mutation of KCNJll gene by directly sequencing. Data for the prese...Objective To compare the distribution ofKCNJll polymorphisms between elderly Chinese population with and without hypertension. Methods We examined the mutation of KCNJll gene by directly sequencing. Data for the present study were obtained from 250 hypertensive subjects （60 to 83 years old） as well as 250 normotensive subjects （60 to 86 years old）. Results We found nine different mutations in KCNJ11, including six novel mutations （1131M, L1471, L147V, L147L, Q235H, G245C）. None of the novel mutations were found in the normotensive subjects, and all the residues were conserved in other species. These sequence variants in Chinese population indicate the diversity of the human library and the complexity of hypertension. Conclusions The consistent finding of our present study provided a basis for the development of new strategies to diagnosis and treat hypertension in the elderly.展开更多
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）.
文摘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.
基金Acknowledgements The authors declare no conflict of interest. This work was supported by the grant from the National Natural Science Foundation of China （81170249, 30700305 and 30400549）, the Key Project of National Natural Science Foundation of China （81030002）, the 10th Five-Year Plan for Scientific and Technological Progress of the military （01MA104）, Chinese Postdoctoral Science Foundation （20080431356）, and Beijing Nova Program （2008A064）.
文摘Objective To compare the distribution ofKCNJll polymorphisms between elderly Chinese population with and without hypertension. Methods We examined the mutation of KCNJll gene by directly sequencing. Data for the present study were obtained from 250 hypertensive subjects （60 to 83 years old） as well as 250 normotensive subjects （60 to 86 years old）. Results We found nine different mutations in KCNJ11, including six novel mutations （1131M, L1471, L147V, L147L, Q235H, G245C）. None of the novel mutations were found in the normotensive subjects, and all the residues were conserved in other species. These sequence variants in Chinese population indicate the diversity of the human library and the complexity of hypertension. Conclusions The consistent finding of our present study provided a basis for the development of new strategies to diagnosis and treat hypertension in the elderly.
