10 Background Lamin A/C mutations are a well-established cause of dilated cardiomyopathy (DCM), although their 11 frequency has not been examined in a large cohort of patients. We sought to examine the frequency of mutations in LMNA, the 12 gene encoding lamin A/C, in patients with idiopathic (IDC) or familial dilated cardiomyopathy (FDC).