Whole genome DNA methylation analysis of human testicular germ cells

For identifying DNA methylation differences in testicular germ cells (TGCs) associated with impaired spermatogenesis, TGCs were isolated from four men with obstructive azoospermia who had normal spermatogenesis and served as controls (CTR) as well as four men with cryptozoospermia (CZ) and impaired spermatogenesis. The DNA was subjected to genome-wide bisulfite sequencing at ~14X coverage. Based on the analysis of H19, MEST, DDX4 and XIST, the samples were judged to be free of somatic DNA. While there was no global difference in DNA methylation between the two groups, we detected region-specific methylation differences, many of which are associated with genes involved in spermatogenesis.