In addition, many studies have shown that in the sperms of patients with oligozoospermia, azoospermia and teratospermia, H19 [38], DAZL [39] and other genes had abnormal DNA methylation levels, and in abnormal sperms after density gradient centrifugation, the abnormal DNA methylation levels were more significant. The gene discussed is DAZL; the disease is Azoospermia.