Laqqan M, et al. - Totalling 200 semen samples were obtained from men (50 proved fertile, 60 normospermia and 90 oligospermia) in order to assess whether there was a difference in the status of global DNA methylation among the study groups and to evaluate their influence on the protamine expression level and human semen parameters. Among the study groups, a notable variation was observed in the global sperm DNA methylation and the protamine 1 and protamine 2 expression level. In the oligospermia group vs the proved fertile group with fold change, down-regulation was noted in the protamine 1 and protamine 2 expression levels. Thus, this study suggested that the modification in global DNA methylation may affect the protamine expression level and could result in abnormalities in human semen parameters.