Does the use of DNA markers improve the accurate diagnosis of long-QT syndrome compared to QTc interval measurement in affected families?
DNA markers provide a more accurate genetic diagnosis of long-QT syndrome than QTc interval measurement, identifying asymptomatic gene carriers.
In families affected by the long-QT syndrome, measurement of the QTc interval may not permit an accurate diagnosis. DNA markers make it possible to make a genetic diagnosis in some families, but not all gene carriers have symptoms.
Vincent et al. (1992) studied this question.