Novel Gain-of-Function Mutation in the Kv11.1 Channel Found in Patient with Brugada Syndrome and Mild QTc Shortening

Brugada syndrome (BrS) is an inherited disease characterized by right precordial ST-segment elevation on electrocardiograms (ECGs), and a high risk of life-threatening ventricular arrhyth-mia and sudden cardiac death. In BrS patients, except for SCN5A, mutations in other responsible genes are poorly elucidated. We identified a new missense mutation, c.1189C>T (p.R397C), in the KCNH2 gene in asymptomatic male proband with diagnosed BrS. We performed patch-clamp analysis on I(Kr) reconstituted with this KCNH2 mutation in Chinese hamster ovary cells and compared the phenotype with the wild type. We found that the R397C mutation increased the I(Kr) density. In silico modeling demonstrated that this missense mutation potentially leads to the shortening of action potential in the heart.