Cardiomyopathy, Familial Hypertrophic, 21, is also known as cmh21. An important gene associated with Cardiomyopathy, Familial Hypertrophic, 21 is CMH21 (Cardiomyopathy, Familial Hypertrophic, 21). Affiliated tissues include heart, and related phenotypes are hypertrophic cardiomyopathy and atrial fibrillation