Table 4. Reduced male fertility with an abnormal proportion of protamines.

Stage	Disease	Aetiology	Species	Reference
Spermatogenesis	Precocious chromatin condensation, transcription arrest, and spermatogenic failure	Deregulation of protamines	Mouse	Cho et al.[5]
	Sperm DNA fragmentation	Abnormally high or low P1/P2 ratios	Human	Simon et al.[98, 99, 100]
	Lowered sperm counts	Haploinsufficiency of protamines	Mouse	Castillo et al.[100]
	Male infertility	The depletion of P2 leads not only to impaired histone to protamine exchange and disturbed DNA-hypercondensation, but also to severe membrane defects resulting in immotility	Mouse	Schneider et al.[101]
	Asthenozoospermia	lower levels of P1 and P2 transcripts or P1/P2 ratio	Human	Kempisty et al.[99]
Embryogenesis	Lower pregnancy rates	Abnormal protamine replacement	Mouse	Cho et al.[5]
	Embryo lethality	Low P2 concentrations	Mouse	Cho et al.[5]