Reclassification of a likely pathogenic Dutch founder variant in KCNH2; implications of reduced penetrance

Background: Variants in KCNH2, encoding the human ether a-go-go (hERG) channel that is responsible for the rapid component of the cardiac delayed rectifier K+ current (IKr), are causal to long QT syndrome type 2 (LQTS2). We identified eight index patients with a new variant of unknown significance (VUS), KCNH2:c.2717C > T:p.(Ser906Leu). We aimed to elucidate the biophysiological effect of this variant, to enable reclassification and consequent clinical decision-making. Methods: A genotype–phenotype overview of the patients and relatives was created. The biophysiological effects were assesse... Mehr ...