ZCCHC13 and Azoospermia: We also observed that 5-Aza-2′-deoxycitidine (5-Aza)-induced demethylation epigenetically increased the expression of ZCCHC13. Taken together, these results for the first time reveal the patterns of methylation and transcription alterations in NOA and provide direct molecular evidence for etiologies of azoospermia.