Substantial variation in qPCR measured mean blood telomere lengths in young men from eleven European countries

Objectives: Telomeres, repetitive DNA sequences found at the ends of chromosomes, shorten with age in proliferating human tissues and are implicated in senescence. Previous studies suggest that shorter telomeres impair immune and cardiovascular function and result in increased mortality. Although few, prior studies have documented ethnic/population differences in human telomere lengths. The nature and cause(s) of these population differences remain poorly understood. Methods: Here, we extend the work of Salpea et al. (2008) by reporting variation in mean blood telomere lengths (BTL) from 765 individuals from 14 study centers across 11 European countries. Subjects are male students (ages 18-28), half of whom had fathers with myocardial infarction before 55 and the remainder age-matched controls. Results: Controlling for age and case-control status, telomere lengths averaged 10.20 kilobases (interpolated from qPCR measures) across study centers and ranged from 5.10 kilobases in Naples, Italy to 18.64 kilobases in Ghent, Belgium-a greater than threefold difference across populations. These population level differences in BTLs were neither explained by national level measures of population genetic structure nor by national level ecological analysis of indices of infection/economic status. Conclusions: These findings suggest considerable population variation in BTL in Europe that is not obviously a result of broad measures of population structure or infection/economic exposure measured in early life or in adulthood. Studying telomere dynamics in a wider variety of populations, and with greater attention to lifecycle dynamics, will be important to help elucidate the causes and possible consequences of human population variation in telomere length.