Researchers at Umeå University in Sweden have shown that the shortening of telomeres in pace with increasing age, as demonstrated in population studies, does not apply at the individual level. The attrition rate seems to mainly depend on the original length of the telomeres, which indicates that some individuals can even have longer telomeres over time.
Chromosomes are a part of DNA and their end structures, telomeres, are important for the genetic stability of cells. Normal cells shorten for each cell division while cancerous cells typically have a stable telomere length. In cell culturing, it has been shown that the activity that contributes to telomere length is primarily active in short telomeres and thus acts as a protection mechanism. The data collected in this new study indicates that a similar mechanism applies to blood cells in the body. The findings also challenge the hypothesis that one could predict a person's life span by studying telomere length.
This study, published in the journal PLoS Genetics, was conducted by a research group led by Professor Göran Roos at the Department of Medical Biosciences, Pathology, and in collaboration with Professor Per Lenner at the Department of Radiation Sciences, Oncology, and Professor Rolf Adolfsson and Karl-Fredrik Norrback, MD, at the Department of Clinical Sciences, Psychiatry.
The study comprised of 959 individuals that donated blood samples on two separate occasions with 9 -11 year intervals. As expected the group found an age-related decline in the blood telomere length, with about one third of the individuals exhibiting a stable or increased telomere length over a decade. The individual telomere attrition rate was inversely correlated to the initial telomere length indicating that individuals with long telomeres at baseline. Corresponding findings were found when telomere length was studied in 13 multigenerational families, by means that families with members displaying longer telomeres at young age displayed the most pronounced shortening.
Abnormal telomere length in blood cells has been reported with cancer patients, but in this material - which includes 314 individuals diagnosed with malignant tumours after the second blood sample - there was no association between telomere length and later cancer diagnosis.
- Nordfjäll K, Svenson U, Norrback K-F, Adolfsson R, Lenner P, Roos G. The individual blood cell telomere attrition rate is telomere length dependent. PLoS Genetics, February 13, 2009 DOI: 10.1371/journal.pgen.1000375
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