Oestrogen receptor gene polymorphisms and ovarian stimulation for in- vitro fertilization

Abstract

Experimental evidence has shown that mice lacking the oestrogen receptor (ESR) gene are infertile with cystic ovaries and follicular arrest. In humans, several polymorphisms and mutations in the ESR gene have been identified. In this study we have analysed a common PvuII and a rare BstUI polymorphism in the ESR gene. Analysis was carried out on DNA samples from women undergoing ovarian stimulation for in-vitro fertilization (IVF) and embryo transfer and controls having at least one pregnancy. Comparisons were done between the three PvuII genotypes, concerning the mean numbers of follicles and oocytes and the mean ratios of follicles to oocytes harvested in two consecutive cycles. Significantly lower ratios were identified in the group lacking the PvuII polymorphism, compared with the groups with heterozygous or homozygous PvuII polymorphisms (P > 0.05 and P > 0.01 respectively). The rare haplotype having both PvuII and BstUI restriction sites on one chromosome was present only in the IVF group. Pregnancies from IVF were significantly rarer in patients who were homozygous for the PvuII polymorphism (P > 0.05). Our results suggest that genetic variability in the ESR has a role in the quality of the ovarian follicles as judged by the ovarian response to stimulation and may also affect implantation.

Do estrogen receptor alpha polymorphisms have any impact on the outcome in an ART program?

“…Some studies report different incidence of the PvuII and XbaI polymorphisms between fertile women and infertile women undergoing IVF [3], while others report no differences between IVF patients and controls [11,30]. The frequencies of the polymorphisms in our sample are comparable with those previously observed in another IVF population [1], despite the different ethnic groups among the two studies.…”

“…The research teams of Georgiou [11] and Sundarrajan [30] were the first to investigate the possible impact of the genotype concerning PvuII polymorphism on ESR1 gene in women undergoing IVF. More recently, Altmäe et al evaluated the impacts of ESR1 PvuII, XbaI and (TA)n genotypes on the etiology of female infertility, as well as their contributions to the COS and pregnancy outcome of IVF in 159 infertile women undergoing IVF-ET [1] .…”

“…The T and C allele of the PvuII are referred as the p and P allele, while the A and G allele of the XbaI are commonly referred as the x and X allele, respectively [31]. PvuII was the first ER polymorphism that has been associated with decreased pregnancy rates after IVF [11,30]. XbaI has also been related with IVF parameters, while both PvuII and XbaI polymorphisms have been associated with the risk of infertility [3].…”

Evaluation of in vitro fertilization parameters and estrogen receptor alpha gene polymorphisms for women with unexplained infertility

“…ESR1 PvuII polymorphism in women was found to affect pregnancy rate following in vitro fertilization (IVF) [7,8], whereas in males ESR1 XbaI polymorphism was suggested to have an effect on azoospermia or idiopathic severe oligospermia [9].…”

“…PvuII polymorphism is reported to be associated with the susceptibility to endometriosis [11] and controlled ovarian hyperstimulation (COH)/pregnancy outcome of IVF [7,8].…”