PLN and Ventricular arrhythmia: Our findings demonstrated that mice carrying the R4344Q variant (Obscn-R4344Q) exhibited a “gain-of-function” phenotype wherein enhanced binding between mutant Ig58 and phospholamban (PLN) resulted in disinhibition of the sarco-endoplasmic reticulum Ca2+ ATPase (SERCA), increased Ca2+ cycling kinetics, and the development of ventricular arrhythmia through aging (6).