Not only do Obscn-ΔIg58/59 male atria mimic the morphological and electrophysiological consequences of this disease, but they also mirror the cellular and molecular hallmarks of ACM class 1, characterized by principal changes to the cardiomyocyte driven by genetic factors that culminate in lone AF in the absence of substantial fibrosis (1). Here, OBSCN is linked to atrial fibrillation.