Hypertrophic cardiomyopathy is an autosomal dominant hereditary disease characterised by left ventricular asymmetry hypertrophy. However, our knowledge of the genetic background in hypertrophic cardiomyopathy cases is limited. Here, we aimed to evaluate pathogenic gene mutations in a family with high-risk hypertrophic cardiomyopathy and analyse the genotype/phenotype relationships in this family.

The proband, her parents, and her niece underwent whole-exome sequencing, and the genotypes of family members were identified using Sanger sequencing. mRNA expression was detected using reverse transcription sequencing. Structural impairments were predicted by homologous modelling. A family survey was conducted for patients with positive results to obtain information on general clinical symptoms, electrocardiography, ambulatory electrocardiography, echocardiography, and 3.0T cardiac magnetic resonance findings. Regular follow-up was performed for up to 6 months.

Five family members, including the proband, carried a cleavage site mutation in the MYBPC3 gene (c.2737+1 (IVS26) G>T), causing exon 26 of the MYBPC3 gene transcript to be skipped and leading to truncation of cardiac myosin-binding protein C. Family survey showed that the earliest onset age was 13 years old, and three people had died suddenly at less than 40 years old. Three pathogenic gene carriers were diagnosed with hypertrophic cardiomyopathy, and all showed severe ventricular septal hypertrophy.

The c.2737+1 (IVS26) G>T mutation in the MYBPC3 gene led to exon 26 skipping, thereby affecting the structure and function of cardiac myosin-binding protein C and leading to severe ventricular hypertrophy and sudden death.