Novel Variations in β-Myosin Heavy-Chain Gene (β-MYH7) and Its Association in South Indian Women with Cardiomyopathies

Background Mutations in β-MYH7 gene is a main genetic cause of cardiomyopathy and sudden cardiac arrest, yet the molecular mechanisms have not been fully understood. Objectives To identify variations in β-MYH7 gene and their possible mechanistic role in cardiomyopathies among Indian women. Methods We sequenced all exons and their flanking regions of the β-MYH7 gene in 188 Indian women consisting of 33 hypertrophic cardiomyopathy (HCM), 48 dilated cardiomyopathy (DCM), and 107 healthy controls. Results Our study showed 21 variations in β-MYH7 gene, including 7 novel mutations. In addition, we compared this dataset with our previously studied datasets of seven other sarcomere genes (ACTC, TNNT2, MYL2, MYBPC3, TPM1, TNNI3, and MYL3) and found no causative mutation, confirming the nonexistence of compound heterozygosity. Interestingly, we detected a Val431Met mutation exclusively in patients, and its pathogenicity has been predicted using the protein homology model. In native, Val431 is evolutionarily conserved across many species. In the homology model, mutant Met431 gets further buried in the hydrophobic core by creating an aberrant hydrophobic interaction with Leu352. As a result, it probably reduces the spatial distances between other hydrophobic interactions in the hydrophobic core that may produce steric hindrance and strain. It may lead to deviation in the structure (root means square deviation [RMSD] of ~3.9), and might possibly causing the cardiac remodeling and cardiomyopathy. Conclusion We identified a novel Val431Met mutation, exclusively in patients, and its homology model p.Met431 has profoundly increased the mechanistic understanding of disease specifically in personalized medicine, to block/inverse/diminish the disease phenotype.