Gender and age effects on ventricular repolarization abnormality in Japanese general carriers of a G643S common single nucleotide polymorphism for the KCNQ1 gene.
BACKGROUND
The KCNQ1 single nucleotide polymorphism (SNP), G643S, is known to be associated with secondary long QT syndrome (LQTS) and to cause a mild reduction in KCNQ1 current. However, the precise incidence and its association with QT intervals remain unknown in the greater cohort of the population in Japan.


RESULTS
The genotype was screened at codon 643 of KCNQ1 in 992 residents of a farming community. Eighty-eight individuals (female/male =52/36, 8.9%) were found to have a heterozygous G643S SNP. Matching both gender and age, we randomly selected 243 control (G643G) cases and compared the electrocardiogram parameters in both groups; QT, QTf (QT corrected by Fridericia's formula) intervals, the peak and the end of the T wave (Tpe) interval, and the Tpe/QT ratio. The latter 2 reflect the transmural dispersion of ventricular repolarization (TDR). In G643S carriers, both Tpe and Tpe/QT were significantly longer than in non-carriers, without significant QT prolongation. Both genders showed a tendency for an increase in QTf with aging. In females, both Tpe and Tpe/QT showed a similar significant increase with age, which was not observed in males.


CONCLUSIONS
In elderly females, G643S might be an independent risk factor for secondary LQTS by causing a greater TDR.
Ozawa
Tomoya
T
Department of Cardiovascular Medicine, Shiga University of Medical Science, Otsu, Japan. ozawat@iris.eonet.ne.jp
Ito
Makoto
M
Tamaki
Shinji
S
Yao
Takenori
T
Ashihara
Takashi
T
Kita
Yoshikuni
Y
Okamura
Tomonori
T
Ueshima
Hirotsugu
H
Horie
Minoru
M
D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D019943:Amino Acid Substitution; D044466:Asian People; D015331:Cohort Studies; D005260:Female; D006801:Humans; D007564:Japan; D051657:KCNQ1 Potassium Channel / Q000235:genetics*; D008133:Long QT Syndrome / Q000235:genetics*; D008297:Male; D008875:Middle Aged; D020641:Polymorphism, Single Nucleotide; D012307:Risk Factors; D012737:Sex Factors
D051657:KCNQ1 Potassium Channel; C496909:KCNQ1 protein, human