Structural effects of the slow/b-cardiac myosin heavy chain R453C mutation in cardiac and skeletal muscle

Objectives. Hypertrophic cardiomyopathy (HCM) represents an important cause of sudden cardiac death particularly in otherwise healthy young individuals. In some families, HCM is caused by distinct mutations of the cardiac beta myosin heavy chain gene (MYH7). Design. We have analyzed the expression of the malignant MYH7Arg453Cys mutation, in cardiac and skeletal muscle, and related it to morphological alterations. Results. Morphological investigation revealed hypertrophic cardiomyocytes but regularly arranged myofibrils. Skeletal muscle showed no sign of structural alterations. Conclusions. Our results indicate that cardiomyocyte hypertrophy is secondary, due to impaired function, and that the mutation causes no structural alteration in myofibrillar structure in cardiac or skeletal muscle.