Association between FSHR and ESR1 gene variants and ovarian response to gonadotropin in Egyptian women undergoing ICSI treatment

Association of FSHR gene polymorphisms with poor ovarian response in patients undergoing IVF: A systematic review and meta-analysis

BACKGROUND

The results of studies on the association between polymorphisms in the FSHR gene and the risk of POR undergoing IVF have been inconsistent with each other, so we conducted a meta-analysis of all the available studies to explore the association between polymorphisms in the FSHR gene and the risk of POR.

METHODS

Literature that met the inclusion criteria was collected by searching six electronic databases and basic data from included studies were extracted. Odds ratios (ORs) and 95% confidence intervals (CIs) were calculated to assess the strength of association between follicle-stimulating hormone receptor (FSHR) gene polymorphism and poor ovarian response (POR) risk. Begg's and Egger's tests were used to determine whether there was publication bias, and sensitivity analysis and TSA analysis were used to verify the stability and reliability of the results.

RESULTS

We included 24 articles, 22 of which explored rs6166, including 2,206 cases and 3,897 controls. 6 articles explored rs6165, including 444 cases and 875 controls. Under additive, heterozygote, and dominant models, rs6166 was significantly associated with POR (S vs. N: OR = 1.29, 95 % CI = 1.05-1.59, P = 0.017; NS vs. NN: OR = 1.33, 95 % CI = 1.02-1.74, P = 0.038; NS + SS vs. NN: OR = 1.38, 95 % CI = 1.04-1.84, P = 0.025). In ethnicity-based subgroup analyses, the additive, homozygote, heterozygote, and dominant models increased Asian POR risk. Among the five genetic models, rs6165 was significantly associated with POR (T vs. C: OR = 1.64, 95 % CI = 1.25-2.16, P = 0.000; TT vs. CC: OR = 2.76, 95 % CI = 1.43-5.32, P = 0.003; CT vs. CC: OR = 1.58, 95 % CI = 1.19-2.10, P = 0.001; TT vs. CC + CT: OR = 2.32, 95 % CI = 1.67-3.23, P = 0.000; CT + TT vs. CC: OR = 1.80, 95 % CI = 1.22-2.65, P = 0.003). In ethnicity-based subgroup analyses, all five genetic models increased the risk of POR in Caucasians.

CONCLUSION

According to the current meta-analysis, the rs6166 S allele was significantly associated with an increased risk of POR, especially in Asian populations. The rs6165 T allele was significantly associated with an increased risk of POR, especially in Caucasian populations.

GDF9His209GlnfsTer6/S428T and GDF9Q321X/S428T bi-allelic variants caused female subfertility with defective follicle enlargement

BACKGROUND

Antral follicles consist of an oocyte cumulus complex surrounding by somatic cells, including mural granulosa cells as the inner layer and theca cells as the outsider layer. The communications between oocytes and granulosa cells have been extensively explored in in vitro studies, however, the role of oocyte-derived factor GDF9 on in vivo antral follicle development remains elusive due to lack of an appropriate animal model. Clinically, the phenotype of GDF9 variants needs to be determined.

METHODS

Whole-exome sequencing (WES) was performed on two unrelated infertile women characterized by an early rise of estradiol level and defect in follicle enlargement. Besides, WES data on 1,039 women undergoing ART treatment were collected. A Gdf9Q308X/S415T mouse model was generated based on the variant found in one of the patients.

RESULTS

Two probands with bi-allelic GDF9 variants (GDF9His209GlnfsTer6/S428T, GDF9Q321X/S428T) and eight GDF9S428T heterozygotes with normal ovarian response were identified. In vitro experiments confirmed that these variants caused reduction of GDF9 secretion, and/or alleviation in BMP15 binding. Gdf9Q308X/S415T mouse model was constructed, which recapitulated the phenotypes in probands with abnormal estrogen secretion and defected follicle enlargement. Further experiments in mouse model showed an earlier expression of STAR in small antral follicles and decreased proliferative capacity in large antral follicles. In addition, RNA sequencing of granulosa cells revealed the transcriptomic profiles related to defective follicle enlargement in the Gdf9Q308X/S415T group. One of the downregulated genes, P4HA2 (a collagen related gene), was found to be stimulated by GDF9 protein, which partly explained the phenotype of defective follicle enlargement.

CONCLUSIONS

GDF9 bi-allelic variants contributed to the defect in antral follicle development. Oocyte itself participated in the regulation of follicle development through GDF9 paracrine effect, highlighting the essential role of oocyte-derived factors on ovarian response.

The FSHR G-29A variant is not associated with the ovarian response to exogenous FSH stimulation

A common genetic variant in the follicle stimulating hormone receptor gene (FSHR) 5'-untranslated region has been previously reported to influence FSHR gene expression. However, studies on the ovarian response to exogenous gonadotropin stimulation are limited. The aim of this study was to evaluate the association of variants at positions -29 of the FSHR gene with the ovarian response to exogenous FSH stimulation in Chinese women. The genotypes of the FSHR gene were assayed using the Sequenom MassARRAY system. Total RNA and protein was extracted from granulosa cells, and FSHR expression at the mRNA and protein levels was assessed using quantitative PCR and western blotting. Our data revealed that there was no association between the FSHR genotype at the -29 position and the outcome of controlled ovarian stimulation. The expression of FSHR, at both the mRNA and protein levels, was similar amongst the different FSHR genotypes assessed, but was significantly reduced in the low responders. These results indicate that the variants caused by mutations at position -29 are not associated with ovarian response, and the low ovarian response to gonadotropin stimulation may be caused by decreased FSHR expression.

Effects of FSHR and FSHB Variants on Hormonal Profile and Reproductive Outcomes of Infertile Women With Endometriosis

BACKGROUND

Single nucleotide variants (SNVs) FSHB:c.-211G>T, FSHR:c.919G>A, and FSHR:c.2039G>A were reported to be associated with the variability in FSH and LH levels, and in vitro fertilization (IVF) outcomes. In this study, we aimed to evaluate the effects of FSHB:c.-211G>T, FSHR:c.919G>A, and FSHR:c.2039G>A variants, alone and combined, on the hormonal profile and reproduction outcomes of women with endometriosis.

METHODS

A cross-sectional study was performed comprising 213 infertile Brazilian women with endometriosis who underwent IVF treatment. Genotyping was performed using TaqMan real-time PCR. Variables were compared according to the genotypes of each variant and genetic models, and the combined effects of the SNVs were evaluated using the multifactorial dimensionality reduction method.

RESULTS

FSHB:c.-211G>T affected LH levels in women with overall endometriosis and minimal/mild disease. FSHR:c.919G>A affected FSH levels in women with overall endometriosis and the number of oocytes retrieved in those with moderate/severe endometriosis. Moreover, the FSHR:c.2039G>A affected FSH levels in women with overall endometriosis, LH levels and total amount of rFSH in those with minimal/mild disease, and number of follicles and number of oocytes retrieved in those with moderate/severe endometriosis. No effect on hormone profile or reproductive outcomes was observed when the genotypes were combined.

CONCLUSIONS

Variants of the FSHB and FSHR genes separately interfered with the hormonal profiles and IVF outcomes of women with endometriosis.