 Since HCM, as an example, is typically an autosomal dominant trait, each child of an HCM parent has a 50% chance of inheriting the mutation.In individuals without a family history, the most common cause of the disease is a "de novo" mutation of the gene that produces the β-myosin heavy chain.Sudden cardiac death can usually be attributed to cardiovascular disease or commotio cordis, but about 20% of cases show no obvious cause and remain undiagnosed after autopsy.