Cardiomyopathies

A 38-year-old man from rural Maharashtra presents with progressive dyspnea on exertion for 6 months and orthopnea for 2 weeks. He denies chest pain, fever, or recent viral illness. Physical examination reveals elevated JVP, bilateral basal crackles, and a displaced apex beat. ECG shows sinus tachycardia and nonspecific ST-T wave changes. Echocardiography demonstrates globally dilated left ventricle (LVEF 28%), normal wall thickness, and no regional wall motion abnormality. Cardiac catheterization shows elevated filling pressures with normal coronary arteries. Blood cultures and serological tests for common infections are negative. What is the most likely diagnosis?

A 42-year-old woman from Delhi presents with progressive dyspnea, palpitations, and syncope on exertion for 8 months. She reports a family history of sudden cardiac death in her mother at age 45. On examination, she has a prominent systolic murmur at the left sternal border that increases with standing and Valsalva maneuver. Blood pressure is 128/82 mmHg. ECG shows marked left ventricular hypertrophy with deep Q waves in the lateral leads and T-wave inversions in V2–V4. Echocardiography reveals asymmetric septal hypertrophy (septum 22 mm, posterior wall 10 mm), systolic anterior motion of the mitral valve, and severe left ventricular outflow tract obstruction (gradient 85 mmHg). Coronary angiography is normal. What is the most likely diagnosis?

Which of the following genetic mutations is most commonly associated with hypertrophic cardiomyopathy (HCM)?