β1-Adrenergic receptor polymorphisms, QTc interval and occurrence of symptoms in type 1 of long QT syndrome

In this relatively small study, double homozygosity for Arg389 and Ser49 of the human β1-adrenergic receptor associated with the risk of symptoms in LQT1. The association between these β1-adrenergic receptor polymorphisms and the symptom history in LQT1 is not mediated via QT interval duration.