Unusual Age-Dependent Behavior of Leukocytes Telomere Length in Friedreich's Ataxia

Friedreich ataxia (FRDA) is an autosomal recessive neurodegenerative disorder caused by an expanded GAA repeat in the first intron of the FXN gene.

The aim of this study was to analyze leukocyte telomeres length (LTL) in FRDA to verify the possible relationships between LTL and disease progression. We investigated LTL in a cohort of FRDA biallelic patients (n = 61), heterozygous (n = 29), and age-matched healthy subjects (n = 87).

LTL was measured by real-time polymerase chain reaction quantitative analysis (qPCR).

The results showed that before 35 years of age, leukocyte telomeres were longer in patients than in controls, whereas the reverse applies in patients above 36 years of age. Interestingly, LTL was greater than controls at any age in heterozygous subjects. This picture mirrors what has been previously observed in vitro in FRDA cultured fibroblasts, showing significantly longer telomeres at early passages because of activation of an alternative lengthening of telomeres (ALT)-like mechanism, but showing accelerated telomere shortening as population doubling increases. GAA1 repeat length is positively correlated with the LTL and negatively correlated with the age at blood sampling. The relationship of LTL with clinical parameters (cardiomyopathy, diabetes, dependence on a wheelchair) was also analyzed. Significantly shorter leukocyte telomeres were associated with the presence of cardiomyopathy, but not with diabetes and the dependence on a wheelchair.

Overall, the present study indicates that telomere length analysis in FRDA may be a relevant biomarker for following the stages of the disease. © 2024 The Author(s). Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.