UC Davis

Shortening of telomere length is a marker of biological aging and a major contributing factor of cellular senescence. Reduced telomere length (TL) has been associated with several age-dependent neurological diseases, including fragile X-associated tremor/ataxia syndrome (FXTAS) and fragile X syndrome. As published studies on telomere repeat lengths in FXTAS were conducted with blood samples, we hypothesized whether this outcome would also be evident in primary fibroblasts from subjects carrying the FMR1 premutation. To test this hypothesis, we used genomic DNA isolated from primary dermal fibroblasts from noncarriers (N=2; male=1, female=1, ages=23, 30 years) and carriers of the premutation affected with FXTAS (N=66; males=40, females=26, age range=15-85 years) and carriers of the premutation not affected with FXTAS (N= 20; males=11, females=9, age range= 10-62 years) to examine the correlation between telomere length and subject’s age and whether the association between telomere shortening may differ among those with and without FXTAS diagnosis or stages of the disease. This was expected as the presence of FXTAS may represent further acceleration of the aging process. The experimental telomere repeat shortening was correlated neither with age nor disease diagnosis or stage. This can be explained by considering uncontrolled confounding factors of the experimental design utilized in this study. Among them, lack of technical replicates across batches, lack of sample randomization in each batch tested, relatively small subject size, limited age range of subjects, and the cross-sectional vs. longitudinal nature of the experimental design.