title: Gender and age effects on ventricular repolarization abnormality in Japanese general carriers of a G643S common single nucleotide polymorphism for the KCNQ1 gene.
abstract: 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.
authors.affiliation: Department of Cardiovascular Medicine, Shiga University of Medical Science, Otsu, Japan. ozawat@iris.eonet.ne.jp
authors.forename: Tomoya
authors.initials: T
authors.lastname: Ozawa
authors.forename: Makoto
authors.initials: M
authors.lastname: Ito
authors.forename: Shinji
authors.initials: S
authors.lastname: Tamaki
authors.forename: Takenori
authors.initials: T
authors.lastname: Yao
authors.forename: Takashi
authors.initials: T
authors.lastname: Ashihara
authors.forename: Yoshikuni
authors.initials: Y
authors.lastname: Kita
authors.forename: Tomonori
authors.initials: T
authors.lastname: Okamura
authors.forename: Hirotsugu
authors.initials: H
authors.lastname: Ueshima
authors.forename: Minoru
authors.initials: M
authors.lastname: Horie
mesh_terms: 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
chemical_list: D051657:KCNQ1 Potassium Channel; C496909:KCNQ1 protein, human