Whole genome DNA methylation analysis of sperm DNA from normozoospermic and oligoasthenoteratozoospermic men

Several studies have reported a higher incidence of imprinting defects in sperm of subfertile patients. Most of these studies investigated only a few genes (e.g. MEST and H19). For evaluating the methylation status of the entire sperm genome, we performed whole genome bisulfite sequencing (WGBS) on DNA isolated from swim-up purified sperm of 5 oligoasthenoteratozoospermic (OAT) patients with aberrant MEST and H19 methylation, 6 OAT patients with normal MEST and H19 methylation as well as 5 normozoospermic men. Based on the methylation levels of all imprinted genes and of more than 2,000 germ cell specific genes, the samples in the first patient group are considered to be contaminated by somatic DNA, while the other samples are free of somatic DNA. We did not detect recurrent DNA methylation differences between the two other groups (OAT patients and normozoospermic men).