Feline hypertrophic cardiomyopathy (HCM) is the most common heart disease in cats; the disease process and genetics are believed to be similar to the disease in humans. In Maine Coon and American Shorthair cat breeds, HCM has been confirmed as an autosomal dominant inherited trait. The first genetic mutation (in cardiac myosin binding protein C) responsible for feline hypertrophic cardiomyopathy was discovered in 2005 in Maine Coon cats. A test for this mutation is available. About one third of Maine Coon cats tested for the mutation have been shown to be either heterozygous or homozygous for the mutation, although many of these cats have no clinical signs of the disease. Some Maine Coon cats with clinical evidence of hypertrophic cardiomyopathy test negative for this mutation, strongly su