Familial hypertrophic cardiomyopathy in Maine coon cats - An animal model of human disease

Background-A naturally occurring animal model of familial hypertrophic card iomyopathy (FHCM) is lacking, We identified a family of Maine coon cats wit h HCM and developed a colony to determine mode of inheritance, phenotypic e xpression, and natural history of the disease. Methods and results-a proband was identified, and related cats were bred to produce a colony. Affected and unaffected cats were bred to determine the mode of inheritance. Echocardiography was used to identify affected offspri ng and determine phenotypic expression, Echocardiograms were repeated seria lly to determine the natural history of the disease. Of 22 offspring from b reeding affected to unaffected cats, 12 (55%) were affected. When affected cats were bred to affected cats, 4 (45%) of the 9 were affected, 2 (22%) un affected, and 3 (33%) stillborn. Findings were consistent with an autosomal dominant mode of inheritance with 100% penetrance, with the stillborns rep resenting lethal homozygotes that died in utero. Affected cats usually did not have phenotypic evidence of HCM before 6 months of age, developed HCM d uring adolescence, and developed severe HCM during young adulthood, Papilla ry muscle hypertrophy that produced midcavitary obstruction and systolic an terior motion of the mitral valve was the most consistent manifestation of HCM. Cats died suddenly (n = 5) or of heart failure (n = 3). Histopathology of the myocardium revealed myocardial fiber disarray, intramural coronary arteriosclerosis, and interstitial fibrosis, Conclusions-HCM in this family of Maine coon cats closely resembles the hum an form of FHCM and should prove a valuable tool for studying the gross, ce llular, and molecular pathophysiology of the disease.