Similar to the whole body Lmna-null mice, Lmnaflox/floxMyh6-Cre mice with Lmna deletion restricted to cardiomyocytes, develop severe cardiac dysfunction and conduction defects, ventricular arrhythmias, cardiac fibrosis, and apoptosis and die within 4 weeks of birth [22,23]. The gene discussed is LMNA; the disease is fibrosis.