Any familial isolated dilated cardiomyopathy in which the cause of the disease is a mutation in the DES gene. The disease is dilated cardiomyopathy 1I (MONDO_0011482). Also known as: CMD1I, DES familial isolated dilated cardiomyopathy, cardiomyopathy, dilated, type 1I, dilated cardiomyopathy type 1I, familial isolated dilated cardiomyopathy caused by mutation in DES.