Alteration of ERβ gene Rsal polymorphism may contribute to reduced fertilization rate and embryonic developmental competence

This paper aims to determine the possible role of estrogen receptor-β （ERβ） gene Rsal polymorphism on sperm fertility and early embryonic development in humans. Three groups of Chinese men were recruited： in vitro fertilization （IVF） group, including 374 couples who underwent conventional IVF; intracytoplasmic sperm injection （ICSI） group, including 294 couples who underwent an ICSI procedure using ejaculated sperm; and azoospermic group, consisting of 197 couples who underwent ICSI using either testis or epididymis sperm. Rsal polymorphism in the ERβ gene was detected by polymerase chain reaction （PCR）-restriction fragment length polymorphism technique; fertilization and high-quality embryo rates were evaluated for each group. In each group, no significant differences were found in the overall rates of fertilization and high-quality embryos among GG, AG and AA genotypes. However, the proportion of cycles possessing a satisfactory high-quality embryo rate with the AA genotype was significantly lower than that in the wild-type GG genotype from each group. These results demonstrated that sperm possessing the ERβ RsalA genotype may have reduced fertilization ability and decreased early embryonic developmental potential, which could directly or indirectly contribute to the low fertilization rate and early embryonic developmental arrest in some cases.