MyBP-C gene mutations were associated with a similar clinical phenotype to beta-myosin heavy chain mutations but had a more benign prognosis, with a 90% survival rate at 50 years (P=0.002).
Observational (n=68)
Does the MyBP-C gene mutation result in a different clinical phenotype or prognosis compared to beta-MHC gene mutations in patients with familial hypertrophic cardiomyopathy?
Mutations in the MyBP-C gene and beta-MHC gene in familial hypertrophic cardiomyopathy share similar phenotypic expressions but differ in long-term prognosis.
p-value: p=0.002
BACKGROUND: The gene involved in familial hypertrophic cardiomyopathy on chromosome 11 was recently identified as the cardiac myosin binding protein-C (MyBP-C) gene. The phenotype of two families associated with mutation in this gene is described here and compared to that of five families with mutations in the beta-myosin heavy chain gene. METHODS AND RESULTS: In adults (n = 33) bearing a splice acceptor site mutation in the MyBP-C gene, penetrance of familial hypertrophic cardiomyopathy was incomplete (69%) and ventricular hypertrophy mild. Among 37 clinical, electrocardiographic and echocardiographic parameters analysed, the only difference with the beta-MHC group (n = 35) was a shorter acceleration time of systolic flow in the pulmonary artery (P < 0.05). Sensitivity and specificity of diagnostic criteria were similar for the two genes. Cumulative survival rate for the splice acceptor site mutation (90% at 50 years old) was mid-way between that observed with a malignant (Arg403Leu: 42%) and a benign mutation (Arg403Trp: 100%) in the beta myosin heavy chain gene (P = 0.002). CONCLUSIONS: The detailed phenotype associated with a mutation in the MyBP-C gene was no different from that associated with mutations in the beta myosin heavy chain gene, except for prognosis which appeared more benign. These preliminary results suggest that there is no locus-specific genotype-phenotype correlation for the two genes analysed.
Philippe Charron (Thu,) conducted a observational in Familial hypertrophic cardiomyopathy (n=68). MyBP-C gene mutation vs. Beta-myosin heavy chain gene mutation was evaluated on Cumulative survival rate at 50 years old (p=0.002). MyBP-C gene mutations were associated with a similar clinical phenotype to beta-myosin heavy chain mutations but had a more benign prognosis, with a 90% survival rate at 50 years (P=0.002).