Background: The long QT syndrome is an inherited disorder with prolonged ventricular repolarization and a propensity to ventricular tachyarrhythmias and sudden arrhythmic death. Recent linkage studies have demonstrated three separate loci for this disorder on chromosomes 3, 7, and 11, and specific mutated genes for long QT syndrome have been identified on two of these chromosomes. We investigated ECG T-wave patterns (phenotypes) in members of families linked to three genetically distinct forms of the long QT syndrome. Methods and Results: Five quantitative ECG repolarization parameters, ie, four Bazett-corrected time intervals (QT(onset-c), QT(peak-c), QT(c) and T(duration-c), in milliseconds) and the absolute height of the T wave (T(amplitude), in millivolts), were measured in 153 members of six families with long QT syndrome linked to markers on chromosomes 3 (n=47), 7 (n=30), and 11 (n=76). Genotypic data were used to define each family member as being affected or unaffected with long aT syndrome. Affected members of all six families had longer QT intervals (QT(onset-c), QT(peak-c), or QT(c)) than unaffected family members (P5. A considerable variability exists in the quantitative repolarization parameters associated with each genotype, with overlap in the T-wave patterns among the three genotypes. Conclusions: Three separate genetic loci for the long QT syndrome including mutations in two cardiac ionic channel genes were associated with different phenotypic T-wave patterns on the ECG. This study provides insight into the influence of genetic factors on ECG manifestations of ventricular repolarization.
|Number of pages||6|
|Publication status||Published - Nov 15 1995|
ASJC Scopus subject areas
- Cardiology and Cardiovascular Medicine