Abstract: Objective To study the disease-causing gene mutations in Chinese hypertrophic cardiomyopathy (HCM) and to reveal the relationship between the genotype and the phenotype. Methods One hundred unrelated patients with HCM and 120 controls were chosen for the study. The full encoding exons and flanking sequences of the cardiac myosin binding protein C gene (MYBPC3) were amplified with PCR and the products were sequenced. The relation between genotype and phenotype was analyzed. Results Mutation G4295A was identified in exon 6 of MYBPC3 gene in two families, which resulted in the glutamic acid (E) converted to lysine (K). Echocardiography showed no obstruction of left ventricular outflow tract in the two HCM probands. This mutation (E258K) resulted in mild HCM phenotypes and showed low penetrance. The 120 controls were normal in the genetic test. Conclusions The G4295A mutation of MYBPC3 gene is the causal mutation of familial HCM with mild phenotype.

Key words: Myosin binding protein C, Hypertrophic cardiomyopathy, Mutation