Whole genome methylation analysis of sperm and blood from young and old men.

Parental age has been steadily increasing in Western societies. While the effects of age on the reproductive function of women are well known, little is known about the reproductive aging of men. For identifying age-specific changes of the DNA methylation in the male germline, we performed whole genome bisulfite sequencing (WGBS) of pooled DNA prepared from sperm and blood DNA (n=6 each) from young (aged 18-24) and old healthy men (aged 61-71). By comparing the four methylomes, we identified more than 200 differentially methylated regions specific for sperm that gained or lost DNA methylation with age. Based on six such regions we derived a predictor for estimating the epigenetic age of sperm.