Chromosome tips might explain why mice carrying mutations for a heritable form of muscular dystrophy do not display the heart problems that eventually kill people with the disease.

Humans with Duchenne muscular dystrophy die young from cardiorespiratory failure, but mice with similar genetic mutations have normal lifespans and only mild symptoms. However, researchers led by Helen Blau at Stanford University in California, showed that mice with the mutation did display severe cardiac defects if, like humans, they also had shortened telomeres, the protective caps on the ends of chromosomes. Heart muscle in these mice showed signs of oxidative stress, a kind of chemical damage associated with shorter telomeres, and this damage could be ameliorated with antioxidants. Follow-up work on heart muscle tissue from four people who had Duchenne muscular dystrophy showed that all four had very short telomeres.

The results could be used to improve animal models for Duchenne muscular dystrophy and to develop ways to slow heart damage, the authors say.

Nature Cell Biol. http://dx.doi.org/10.1038/ncb2790 (2013)