It is unusual for hypertrophic cardiomyopathy to become manifest before the age of 14 years. The adult-onset disease is caused by mutations in any of a number of genes that encode sarcomere proteins. These include the genes for cardiac β-myosin heavy chain (MYH7), cardiac myosin-binding protein C (MYBPC3), cardiac troponin T (TNNT2), cardiac troponin 1 (TNNI3), essential myosin light chain (MYL3), regulatory myosin light chain (MYL2), α tropomyosin (TPM1), cardiac actin (ACTC) and titin (TTN). Gene mutations known …