Genetic Evaluation of Hypertrophic Cardiomyopathy

Abstract

Hypertrophic cardiomyopathy (HCM) is defined as left ventricular hypertrophy in the absence of abnormal loading conditions. In 50–60% of adolescents and adults with HCM, the disease is inherited as an autosomal dominant trait caused by mutations in cardiac sarcomere protein genes. The most cases are due to mutations in genes which determine the synthesis of myosin-binding protein C (MYBPC3) and beta-myosin heavy chain (MYH7). More rarely involved genes are those encoding myosin light chain 3 (MYL3), tropomyosin alpha-1 chain (TPM1), and cardiac troponins I and T (TNNI3, TNNT2). Mutations in genes encoding Z-disc or calcium-handling proteins account for less than 1% of cases. Multiple sarcomeric protein mutations are present in up to 5% of individuals. A further of 5% of patients have inherited metabolic or neuromuscular diseases, chromosome abnormalities, and genetic syndromes. HCM is characterized by a highly heterogeneous phenotype, highly variable intraand interfamily expressivity and incomplete penetrance, therefore by a genotype-phenotype plasticity.