TNNT2 and Schnyder corneal dystrophy: HCM is typically caused by mutations in genes encoding protein components of the cardiac sarcomere (http://genetics.med.harvard.edu/∼seidman/cg3/index.html), with the three most common causes being mutations in the genes encoding beta cardiac myosin heavy chain (MYH7), cardiac troponin T (TNNT2), and myosin binding protein C. Although the phenotypes resulting from these genetic defects vary greatly, mutations in TNNT2 in humans3,4 and in animal models5,6 have frequently resulted in an increased susceptibility to SCD, often in the presence of mild or absent cardiac hypertrophy.