A 30-year-old athlete collapses during a football match and is successfully resuscitated from ventricular fibrillation. Echo shows asymmetric septal hypertrophy (IVS 20 mm), SAM of the mitral valve, and LVOTO gradient of 55 mmHg at rest. What is the most likely genetic defect?

• A Mutations in dystrophin gene (DMD)
• B Mutations in desmoplakin/plakophilin (ARVC)
• C Lamin A/C mutations
• D Mutations in sarcomere protein genes (most commonly beta-myosin heavy chain or myosin-binding protein C) ✓

Explanation

Hypertrophic cardiomyopathy (HCM) is caused by mutations in sarcomere protein genes in ~60% of familial cases. The most common are beta-myosin heavy chain (MYH7, ~30–35%) and myosin-binding protein C (MYBPC3, ~30–35%). HCM is the most common cause of sudden cardiac death in young athletes. SAM (systolic anterior motion) of the mitral valve causes LVOTO. ARVC (desmoplakin/plakophilin mutations) causes RV fatty infiltration and VT from the right ventricle. Lamin A/C mutations cause dilated cardiomyopathy with conduction disease.

Reference: Harrison's Principles of Internal Medicine, 21st ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.