Maine Coon
Feline hypertrophic cardiomyopathy (HCM) is the most common heart disease in domestic cats; the disease process and genetics are believed to be similar to the disease in humans. In Maine Coon cats, HCM has been confirmed as an autosomal dominant inherited trait. Numerous cat breeds have HCM as a problem in the breed. The first genetic mutation (in cardiac myosin binding protein C) responsible for feline HCM was discovered in 2005 in Maine Coon cats. A test for this mutation (A31P) is available. About one-third of Maine Coon cats tested for the mutation are either heterozygous or homozygous for the mutation, although many of the cats that are heterozygous have no overt evidence of the disease on an echocardiogram (low penetrance). Some Maine Coon cats with clinical evidence of hypertrophic cardiomyopathy test negative for this mutation, strongly suggesting that another cause exists in the breed. The cardiac myosin binding protein C mutation identified in Maine Coon cats has not been found in any other breed of cat with HCM, but more recently another myosin binding protein C mutation has been identified in Ragdoll cats with HCM. As in humans, feline HCM is not present at birth but develops over time. It has been identified for the first time in cats as young as 6 months of age and at least as old as 7 years of age.