Echocardiographic characterization of hypertrophic cardiomyopathy in Chinese patients with myosin-binding protein C3 mutations.

Hypertrophic cardiomyopathy (HCM) is a common autosomal dominant cardiac disease, affecting 1 in 500 people. Myosin-binding protein C3 (MyBPC3) gene mutations are the most common genetic cause of HCM. However, the prevalence of the MyBPC3 gene mutation in Chinese patients with HCM, and their echocardiographic characteristics, remain unknown. In the present study, 48 Chinese patients with HCM were sequenced to identify the MyBPC3 gene and were characterized by their clinical features using 2-dimensional echocardiography and real-time 3-dimensional echocardiography. Nine MyBPC3 mutations were identified in seven unrelated patients out of 48 cases, which accounts for a 15% prevalence of MyBPC3 mutations in Chinese patients with HCM. Family members of the seven patients were further tested and divided into the following two groups based on HCM phenotype and MyBPC3 mutations: Positive genotype with left ventricular (LV) hypertrophy (LVH) (G+/LVH+, n=18); and positive genotype without LVH (G+/LVH-, n=23). These groups were compared with matched normal control subjects (n=30). G+/LVH+ patients showed significantly lower septal and lateral Tissue Doppler imaging (TDI)-derived systolic, early and late diastolic mitral annular velocities compared with the controls. In addition, diastolic dyssynchrony index (DDI) was markedly higher in the G+/LVH+ subjects. However, only septal Ea was significantly lower in G+/LVH- subjects in comparison with controls, with no significant difference in lateral Sa, Ea and Aa, and DDI. In conclusion, the patients in the present study demonstrated a 15% prevalence of MyBPC3 gene mutations in the Chinese HCM population. MyBPC3 gene mutations may cause regional LV hypertrophic remodeling first and further proceed to global hypertrophic remodeling and myocardial diastolic dysfunction.