LMNA and atrioventricular block: Hasselberg et al. found a prevalence of 6.2% for LMNA mutation in familial DCM, and young asymptomatic LMNA genotype-positive family members had high cardiac penetrance, 32% had atrioventricular block, 23% atrial fibrillation, and 39% non-sustained ventricular tachycardia (VT) (45).