In the absence of other factors it has been assumed that cardiac sudden death in young athletes has a genetic basis, but the identity of the genes involved was not known. In 22 April advanced online Nature Genetics, Amy Sehnert and colleagues from University of California at San Francisco (UCSF) have identified a single mutation in TNNT2 that may cause hypertrophic cardiomyopathy (Nat Genet 2002, DOI:10.1038/ng875).

Sehnert et al. investigated cardiac function in a mutant embryo of the zebra fish, a non-contractile heart phenotype dubbed 'silent heart' (sih). The mutant fish lives for roughly seven days post-fertilization by surviving on diffused oxygen rather than circulating blood. Immunochemistry in the sih mutants indicated that the contractile proteins troponin T (tnnt2) and cardiac troponins C and I (tnni3) are totally absent, and that there are significant reductions in α-tropomyosin (Tpma). Consequently, there are severe sarcomere defects in...