Dramatically different phenotypic expressions of hypertrophic cardiomyopathy in male cousins undergoing cardiac transplantation with identical disease-causing gene mutation.

Described herein are certain findings in 2 male cousins who underwent cardiac transplantation for severe heart failure (HF), one of the diastolic type (ejection fraction ≈65%), and one of the systolic type (ejection fraction ≈20%), both the consequence of hypertrophic cardiomyopathy (HC), and each had identical disease-causing gene mutations. The implanted heart in one had normal-sized ventricular cavities and no grossly visible ventricular wall lesions (except in one papillary muscle) and the other patient had severely dilated ventricular cavities and multiple extensive ventricular wall scars. The heart mass and the age of onset of symptoms was similar in each patient. A number of other family members had evidence of HC.