While phenotypic heterogeneity and incomplete penetrance are common features of inherited cardiac diseases, it is unclear how divergent cardiac phenotypes emerge from the same mutation, and so exemplified by the structural and arrhythmogenic pathologies caused by the Ala119Thr mutation in ACTN2. The ACTN2 protein primarily functions to anchor and crosslink actin filaments in the cardiac Z-disc at the lateral boundaries of the sarcomere [15]. Here, ACTN2 is linked to heart disorder.