SCN5A and long QT syndrome 3: Additionally, in long QT syndrome type 3 (LQT3; a disorder stemming from pathological gain of NaV1.5 function), the Poelzing group recently demonstrated that transient depletion of extracellular Na+ within perinexal nanodomains may mitigate risk of premature beats, and that perinexal widening may unmask the latent arrhythmia risk (Greer-Short et al., 2017).