Novel pathogenic variant of MYBPC3 responsible for hypertrophic cardiomyopathy.

Objectives This study aims to investigate the pathogenic gene variant in a family with hypertrophic cardiomyopathy by using whole-exome sequencing and to explore the relationship between the gene variant and clinical phenotype. Methods Peripheral blood was collected from a family with hypertrophic cardiomyopathy, and deoxyribonucleic acid was extracted. The possible pathogenic genes were detected by whole-exome sequencing, and the variant was verified by Sanger sequencing. Functional change in the variant was predicted by bioinformatics software. Clinical data of the family members are analysed simultaneously. Results The proband carries a novel heterozygous nonsense variant of MYBPC3:c.2731G > T (p.E911X). The analysis of amino acid conservation suggests that the variation is highly conserved. The three-dimensional protein structure shows that the variant in MYBPC3 results in the incompleteness of the fibronectintype-III2 (p872-967) domain and deletion of Ig-like C2-type 6 (p971-1065) and fibronectin type-III 3 and Ig-like C2-type 7 (p1181-1274) domains, in which p1253-1268 is predicted to have a transmembrane helix structure. Clinical data indicate that the phenotypes of variant carriers with hypertrophic cardiomyopathy are diverse, suggesting the functional damages to the protein of MYBPC3. Conclusion The phenotypes of variant carriers with hypertrophic cardiomyopathy caused by the novel variant in MYBPC3: c.2731G > T (p.E911X) exhibit variable severity and clinical manifestations. Whole-exome sequencing can be used to comprehensive screen hypertrophic cardiomyopathy genes and provide a strong basis for early screening and accurate diagnosis and treatment of hypertrophic cardiomyopathy in children.