lymphopenia, kyphosis and osteoporosis, mild glucose intolerance and other classic age-related phenotypes26. The severity of these degenerative phenotypes parallels the degree of telomere dysfunction in successive Terc−/− generations, as measured by the number of chromosomal fusions and anaphase bridges and, in a more recent study, the number of DNA damage foci at telomeres60,61. Moreover, the relevance of telomeres to the ageing process was reinforced by the strikingly muted ageing phenotypes of mice engineered with classic human degenerative-disease mutations (for example WRN and AT M), unless such mutant mice were rendered telomerase deficient and possessed short, limiting telomeres62,63.
