Investigation of Leukocyte Telomere Length (LTL) in a cohort of Iranian subjects

We investigated relative LTL in a cohort of 334 subjects (17-85 years, 69% women) from different ethnicities in Iran. The cohort included 127 unrelated nonsmoker healthy subjects (73% female, 78% Persian) that were clinically examined to have no sign of chronic infections, cancers, or cardiovascular diseases, and lived at least 10 years in their current city. We also studied 53 morbidly obese subjects, and 154 samples with unknown health condition from Genetics Research Center DNA bank. All samples quantified against a 5 point standard curve using a mixture of 5 genomic DNA with different chronological ages as reference DNA. Quantitation was done based on relative standard curve using standards to determine the relative quantity of telomere for each sample. The ratio of telomere to single copy gene was calculated and normalized by this ratio for K562 genomic DNA from the same plate.Primary analysis of 127 healthy subjects showed that telomere length decreased as age increased, women had longer telomeres than men (p-value = 0.033), and individuals from Persian ethnicity had longer telomeres than other ethnicities (p-value = 0.000). We classified all 334 samples into 5-year age groups, and found reverse correlation (r = - 0.886) between age and LTL that is fitted in a linear regression model (r2= 0.8100, p-value= 0.000012). This study confirms the association between age and LTL in Iranian individuals and the need of a population based database to use LTL as a biomarker for biological age and age-related diseases.