TTN and familial dilated cardiomyopathy: Approximately 50% idiopathic DCM cases are assigned to genetic causes in familial or apparently sporadic cases,[2] and more than 50 genes are reported to cause DCM.[3] These genes encode components of the sarcomere, desmosome, cytoskeleton, nuclear lamina and mitochondria, and calcium-handling proteins.[3] Pathogenic variants in the TTN gene, which codes for TITIN located in the sarcomere, account for nearly 30% to 35% of familial DCM cases.