A Novel SCN5A Mutation Found in a Familial Case of Long QT Syndrome Complicated by Severe Left Ventricular Dysfunction

A 16-year-old boy with long QT syndrome type 3 (LQT3) was admitted for decompensated heart failure resulting from dilated cardiomyopathy (DCM). His brother was also diagnosed with LQT3 and DCM. A comprehensive genetic analysis identified a novel SCN5A missense mutation—p.Q371E—in these 2 affected living family members. It might be important to suspect the coexistence of DCM and LQT3 (which is rare according to previous articles) in cases with this novel SCN5A missense mutation.