Mutations in genes such as the troponin T (TNNI2)14, troponin I (TNNI3)15, alpha-cardiac actin (ACTC)16 and beta-myosin heavy chain (MYH7)17 genes have been shown to be a major cause of familial RCM. This evidence concerns the gene ACTC1 and cardiomyopathy, familial restrictive, 1.