Epigenetic Clock and Relative Telomere Length Represent Largely Different Aspects of Aging in the Berlin Aging Study II (BASE-II).

DNA methylation age (DNAm age; "epigenetic clock") has recently been described as highly correlated with chronological age. Several studies suggest that DNAm age reflects, at least in part, biological age. Here, we adapted a recently published methylation-sensitive single nucleotide primer extension method for epigenetic age estimation and calculated the DNAm age based on only seven cytosine-phosphate-guanine sites in 1,895 DNA samples of the Berlin Aging Study II. In a second step, we explored the relationship between this new potential measure of biological age with an established marker of biological age, relative leukocyte telomere length (rLTL), in the same cohort. Our results showed a positive and significant correlation between DNAm age estimation and chronological age (N = 1,895, Rs2 = .47), which persisted after adjustment for covariates (sex, leukocyte distribution, alcohol and smoking). We found a significant but weak negative association between DNAm age acceleration and rLTL in linear regression analysis adjusted for age, sex, alcohol and smoking (β = -0.002, p = .007). Therefore, DNAm age appears to be a promising biomarker in the analysis of phenotypes of aging, which are not (only) related to pathways associated with mitotic age as measured by rLTL.