Age-Adjusted Telomere Length Is Not Associated with Variation in Hematological Parameters in Ageing Women

Background. Telomeres play a crucial role in maintaining physical integrity of chromosomes. In the absence of telomerase, telomere length (TL) shortens with each cell division up to a critical threshold where cellular senescence occurs. TL is inversely correlated with age, is longer in women than in men, and demonstrates a strong heritability. Normal blood counts are maintained through out life by an extraordinary number of cell divisions rendering telomere maintenance primordial to prevent stem cell exhaustion. In fact, some cases of bone marrow failure syndromes, such as aplastic anemia and dyskeratosis congenital, have been linked to mutation in the telomerase gene; and stressed hematopoiesis, such at it occurs during the first year following allogeneic bone marrow transplantation induces TL shortening. We hypothesized that individuals with shorter TL may have lower blood counts and a decreased bone marrow reserve. The evaluation of TL as a potential biomarker of ageing hematopoiesis is important in the context of bone marrow transplantation performed with increasingly old donors.

Methods. We measured TL in 1583 women, predominantly aged over 60, all originating from 288 French-Canadian families using a real-time quantitative PCR method that measures the number of telomere repeats relatively to the copy number of a single copy number gene. Telomeres were adjusted for age. Pearson or Spearman correlations were used to determine association between age-adjusted TL (aTL) and hematological parameter according to, respectively, whether or not a normal distribution was observed for these data. A Bonferroni correction was further applied to set the statistical significance threshold.

Results. aTL varied significantly between individuals of the cohort, but no correlation was detected with hemoglobin levels (−0,001; p=0,978), mean corpuscular volume (−0,031; p=0,403); leucocytes (0,055; p=0,139); neutrophils (0,078; p=0,036), monocytes, (0,059; p=0,113), eosinophils (−0,032; p=0,394) and platelets (0,030; p=0,428) counts.

Conclusion. Based on our analysis, TL do not predict blood cells counts in ageing women and may not be a useful biomarker for donor selection. This could also suggest that there is a threshold beyond which TL has an effect on hematopoiesis and that point was not reached in our cohort.