Abstract

Background and Aim: All studies on mammals and rodents have revealed the presence of protamine 1 (P1) and protamine 2 (P2) in the sperm which is indicative of the expression of these two genes at different molecular levels. The aim of this study was to investigate the effect of protamine and its disorders on male fertility potential. Materials and Methods: Using keywords of sperm, protamine, male infertility, and chromatin we searched PubMed and Google Scholar databases between 1980 and 2020. Results: Sperm concentration, motility, and morphology in the patients with variable P1/P2 ratios were significantly reduced compared to those in the individuals with normal P1/P2 ratios which were directly associated with reduced fertility rate. The most common protamine abnormality in the infertile men was increased P1/P2 ratio which was frequently associated with a decreased level of P2 and increased level of P2 precursors. Increased levels of histone B2 (H2B) in sperm and lower levels of protamine have been reported. Any disturbances in the histone expression process cause inconvenient early chromatin condensation, transcription arrest, as well as spermatogenesis failures. Conclusion: The results of this study showed that the protamine transcripts ratio can be used as a marker for male fertility. Histones/protamines mRNAs ratios are important for sperm quality and therefore can be used as predictors for male infertility. Altered levels of protamines may result in an increased susceptibility to injury in the sperm DNA causing infertility or poor outcome in assisted reproduction. © 2018 the Author (s).