Hypertrophic cardiomyopathy (HCM) most commonly involves a mutation in the gene encoding which sarcomeric protein?

• A Dystrophin
• B Desmin
• C Lamin A/C (LMNA)
• D Beta-myosin heavy chain (MYH7) ✓

Explanation

HCM is predominantly an autosomal dominant disorder, and the most common mutations occur in MYH7 (encoding beta-myosin heavy chain) and MYBPC3 (myosin-binding protein C), together accounting for ~50-60% of HCM cases. These mutations cause hypercontractile sarcomeres, asymmetric septal hypertrophy, myocyte disarray, and fibrosis. Dystrophin mutations cause Duchenne/Becker muscular dystrophy-associated dilated cardiomyopathy. Desmin mutations cause desminopathies with conduction defects and dilated or restrictive cardiomyopathy. LMNA mutations cause dilated cardiomyopathy with prominent conduction disease.

Reference: Robbins & Cotran Pathologic Basis of Disease, 10th ed.

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