Divergence of sperm and leukocyte age-dependent telomere dynamics: implications for male-driven evolution of telomere length in humans.
Level 4 - case-series / case-control
Cross-sectional observational study
PubMed 22782639 · doi:10.1093/molehr/gas028
What was done
Leukocyte telomere length (LTL) and sperm telomere length were measured concurrently in 135 men (mean age 34.4 years, range 18–68 years) to evaluate within-individual age-dependent telomere dynamics. Mathematical modeling based on published hematopoietic stem cell and male germ cell replication rates was applied to estimate base-pair changes per replication and evaluate the paternal age at conception (PAC) effect on offspring telomere length.
What was found
LTL decreased with age at an average rate of 19 bp/year (r = -0.3, P = 0.0004), whereas sperm telomere length increased with age by 57 bp/year (r = 0.32, P = 0.0002). Based on cell replication models, hematopoietic stem cells were estimated to lose 26 bp per replication while male germ cells gained 2.48 bp per replication. The observed sperm telomere elongation rate was consistent with predictions for paternal age effects observed in external datasets.
Why it matters
This study directly contrasts somatic and germline telomere dynamics within the same individuals across a wide age range, providing a biological mechanism for why older paternal age at conception is associated with longer telomeres in offspring.
Limits
The study is cross-sectional rather than longitudinal, inferring yearly rates from differences across individuals. The sample size is modest (n = 135), the participants' own offspring were not measured directly, and per-replication rate estimates depend on model assumptions from external literature.
Cited by
- supports Unlike other cell types, sperm telomeres lengthen as men age, and older fathers pass on longer telomeres to their offspring.