Rare genetic variants previously associated with congenital forms of long QT syndrome have little or no effect on the QT interval. - Ghouse J; Have CT; Weeke P; Bille Nielsen J; Ahlberg G; Balslev-Harder M; Appel EV; Skaaby T; Olesen SP; Grarup N; Linneberg A; Pedersen O; et al. (European heart journal, 2015)