DMD and familial dilated cardiomyopathy: Mutations causing XL-DCM or mild BMD with DCM are generally classified into four regions throughout the DMD gene: (1) the region of the muscle promoter to exon 1; (2) the region from exon 2–8 coding the actin binding domain; (3) the region from exon 45–55 (considered the hot-spot for mutations in the DMD gene that encodes the rod domain); and (4) the remaining region [75].