[Correlation between genotype and clinical phenotype in hypertrophic cardiomyopathy families with MYH7-R453C...

Objective: To analyze the relationship between genotype and clinical phenotype of the MYH7-R453C mutation in five Chinese hypertrophic cardiomyopathy (HCM) families. Methods: A retrospective cohort study was conducted on 527 unrelated HCM probands who were first diagnosed at the First Affiliated Hospital of Air Force Medical University (Xijing Hospital) from February 2014 to July 2018, and the high-throughput whole exome targeted sequencing of 96 genes related to hereditary cardiovascular disease was performed on the probands. The probands carrying the MYH7-R453C mutation were screened out, and their family members carrying the mutation were verified using Sanger sequencing. Healthy individuals without family history of genetic diseases from the same period and ethnicity were recruited as controls. Clinical data such as echocardiography, 12-lead electrocardiogram, and cardiac magnetic resonance imaging of the probands and their family members were collected, and the correlation between patient genotype and clinical phenotype was analyzed. Endpoint or key events were recorded through hospital re-examination or telephone follow-up. Results: The MYH7-R453C mutation was detected in 5 HCM probands, and clinical data and genetic results of 20 family members, including probands, were collected. Among them, 13 carried the MYH7-R453C mutation, of which 12 were diagnosed with HCM, and one child (F1Ⅲ₅) experienced early changes of HCM. The seven family members who did not carry the MYH7-R453C mutation had normal echocardiograms and 12-lead electrocardiograms. Among the 12 patients diagnosed with HCM, 2 experienced (F2Ⅱ₇, F5Ⅰ₂) sudden cardiac death, 2 experienced (F1Ⅲ₁, F3Ⅲ₃) events of sudden cardiac death survival, 2(F1Ⅱ₂, F3Ⅱ₁) died from heart failure during the follow-up period. Combined with the initial visit and follow-up, 4 families (F1, F2, F3, F5) had a family history of sudden death, among which 3 families probands or multiple family members experiencing sudden death before the age of 30 and adverse outcomes such as implantation of implantable cardioverter-defibrillators after sudden death survival. Conclusions: In the five families with HCM carrying MYH7-R453C mutations, genotype is highly correlated with clinical phenotype, and patients have a high risk of sudden death and poor prognosis. Early diagnosis of individuals carrying the MYH7-R453C gene mutation, both within the patient's family and in the patients themselves, is crucial for initiating early treatment, preventing sudden death, and assessing prognosis.