OBJECTIVE: To evaluate whether aberrant sperm P1/P2 ratios are predictive of abnormal fertilizing ability and are related to in vitro fertilization (IVF) outcome. DESIGN: Prospective case-control study. SETTING: University-based infertility and IVF clinic. PATIENT(S): Forty-three male infertility patients with an abnormally reduced P1/P2 ratio, 251 patients with a normal P1/P2 ratio, and 121 patients with an abnormally elevated P1/P2 ratio. INTERVENTION(S): Human IVF, the sperm penetration assay (SPA), and sperm protamine quantification via nuclear protein extraction, gel electrophoresis, and densitometry analysis. MAIN OUTCOME MEASURE(S): Sperm P1/P2 ratios; P1 and P2 quantities; SPA scores; and IVF-fertilization, embryo-quality, pregnancy, delivery, and spontaneous-abortion rates. RESULT(S): Standard IVF fertilization rates and SPA scores were significantly reduced in patients with abnormally low and high P1/P2 ratios. In vitro fertilization embryo quality was comparable between these groups, but pregnancy rates were significantly reduced in patients with abnormally reduced P1/P2 ratios. CONCLUSION(S): The P1/P2 ratio has a significant relationship to sperm fertilization ability. The relationship between protamines and fertilization ability is not understood but may be either a reflection of generalized abnormalities during spermiogenesis or an indication of protamine deficiency acting as a regulator or checkpoint of spermatogenesis.
OBJECTIVE: To evaluate whether aberrant sperm P1/P2 ratios are predictive of abnormal fertilizing ability and are related to in vitro fertilization (IVF) outcome. DESIGN: Prospective case-control study. SETTING: University-based infertility and IVF clinic. PATIENT(S): Forty-three male infertilitypatients with an abnormally reduced P1/P2 ratio, 251 patients with a normal P1/P2 ratio, and 121 patients with an abnormally elevated P1/P2 ratio. INTERVENTION(S): HumanIVF, the sperm penetration assay (SPA), and sperm protamine quantification via nuclear protein extraction, gel electrophoresis, and densitometry analysis. MAIN OUTCOME MEASURE(S): Sperm P1/P2 ratios; P1 and P2 quantities; SPA scores; and IVF-fertilization, embryo-quality, pregnancy, delivery, and spontaneous-abortion rates. RESULT(S): Standard IVF fertilization rates and SPA scores were significantly reduced in patients with abnormally low and high P1/P2 ratios. In vitro fertilization embryo quality was comparable between these groups, but pregnancy rates were significantly reduced in patients with abnormally reduced P1/P2 ratios. CONCLUSION(S): The P1/P2 ratio has a significant relationship to sperm fertilization ability. The relationship between protamines and fertilization ability is not understood but may be either a reflection of generalized abnormalities during spermiogenesis or an indication of protamine deficiency acting as a regulator or checkpoint of spermatogenesis.