Genome-wide analysis shows no genomic predictors of ovarian response to stimulation by exogenous FSH for IVF

Identification of common genetic polymorphisms associated with down-regulated gonadotropin levels in an exome-wide association study

OBJECTIVE

To investigate whether common genetic polymorphisms are associated with gonadotropin levels after down-regulation with daily gonadotropin-releasing hormone agonist and whether the polymorphisms of candidate variants influence the ovarian response to exogenous gonadotropins.

DESIGN

Genetic association study.

SETTING

University-affiliated in vitro fertilization center.

PATIENTS

Subjects enrolled in an exploratory exome-wide association study (n = 862), a replication exome-wide association study (n = 86), and a classifier validation study (n = 148) were recruited from September 2016 to October 2018, September 2019 to September 2020, and January 2021 to December 2021, respectively. The included patients were aged ≤40 years and had a basal follicle-stimulating hormone (FSH) ≤12 IU/L.

INTERVENTIONS

All participants received a luteal phase down-regulation long protocol. Genome DNA was extracted from the peripheral blood leukocytes. For the exploratory and replication cohorts, exome sequencing was conducted on a HiSeq 2500 sequencing platform. The multiplex polymerase chain reaction amplification technique and next-generation sequencing also were performed in the exploratory and replication cohorts. For the samples of the validation cohort, Sanger sequencing was performed.

MAIN OUTCOME MEASURES

The primary endpoint was the gonadotropin levels after down-regulation, and the secondary endpoints were hormone levels and follicle diameters during stimulation, the total dose of FSH, duration of FSH stimulation, number of oocytes retrieved, and clinical pregnancy rate.

RESULTS

In the exploratory cohort, we identified that FSHB rs6169 (P=2.71 × 10-24) and its single-nucleotide polymorphisms in high linkage disequilibrium were associated with the down-regulated FSH level. The same locus was confirmed in the replication cohort. Women carrying the C allele of FSHB rs6169 exhibited higher average estradiol level during stimulation (P=6.82 × 10-5), shorter duration of stimulation, and less amount of exogenous FSH (Pduration=0.0002; Pdose=0.0024). In the independent validation set, adding rs6169 genotypes into the prediction model for FSH level after down-regulation enhanced the area under the curve from 0.560 to 0.712 in a logistic regression model, and increased prediction accuracy by 41.05% when a support vector machine classifier was applied.

CONCLUSION

The C allele of FSHB rs6169 is a susceptibility site for the relatively high level of FSH after down-regulation, which may be associated with increased ovarian FSH sensitivity.

Demographic and evolutionary trends in ovarian function and aging

BACKGROUND

The human female reproductive lifespan is regulated by the dynamics of ovarian function, which in turn is influenced by several factors: from the basic molecular biological mechanisms governing folliculogenesis, to environmental and lifestyle factors affecting the ovarian reserve between conception and menopause. From a broader point of view, global and regional demographic trends play an additional important role in shaping the female reproductive lifespan, and finally, influences on an evolutionary scale have led to the reproductive senescence that precedes somatic senescence in humans.

OBJECTIVE AND RATIONALE

The narrative review covers reproductive medicine, by integrating the molecular mechanisms of ovarian function and aging with short-term demographic and long-term evolutionary trends.

SEARCH METHODS

PubMed and Google Scholar searches were performed with relevant keywords (menopause, folliculogenesis, reproductive aging, reproductive lifespan and life history theory). The reviewed articles and their references were restricted to those written in English.

OUTCOMES

We discuss and summarize the rapidly accumulating information from large-scale population-based and single-reproductive-cell genomic studies, their constraints and advantages in the context of female reproductive aging as well as their possible evolutionary significance on the life history trajectory from foetal-stage folliculogenesis until cessation of ovarian function in menopause. The relevant environmental and lifestyle factors and demographic trends are also discussed in the framework of predominant evolutionary hypotheses explaining the origin and maintenance of menopause.

WIDER IMPLICATIONS

The high speed at which new data are generated has so far raised more questions than it has provided solid answers and has been paralleled by a lack of satisfactory interpretations of the findings in the context of human life history theory. Therefore, the recent flood of data could offer an unprecedented tool for future research to possibly confirm or rewrite human evolutionary reproductive history, at the same time providing novel grounds for patient counselling and family planning strategies.

Pharmacology of medications used for ovarian stimulation

Medications to stimulate the ovaries may be used to induce ovulation in patients with anovulatory infertility or to hyperstimulate the ovaries in a controlled fashion in ovulatory patients as part of assisted reproductive treatments (ART). The pharmacology of all current major medications used to stimulate ovarian function is reviewed in this article, including letrozole, clomiphene citrate, gonadotropins, and pulsatile gonadotropin releasing hormone (GnRH). Novel potential compounds and adjuvant treatment approaches are also discussed, such as kisspeptin agonists and androgens.

Pharmacogenetic algorithm for individualized controlled ovarian stimulation in assisted reproductive technology cycles

Controlled ovarian stimulation (COS) is crucial for optimizing in-vitro fertilization (IVF)/intracytoplasmic sperm injection (ICSI) success. Multiple factors influence the ovarian response to COS, making predictions about oocyte yields not so straightforward. As a result, the ovarian response may be poor or suboptimal, or even excessive, all of which have negative consequences for the affected patient. There is a group of patients that present with a suboptimal response to COS despite normal biomarkers of ovarian reserve, such as AFC and AMH. These patients have a lower number of retrieved oocytes than what was expected based on their ovarian reserve, thus showing the inadequacy of using only the traditional ovarian reserve biomarkers to predict the ovarian response. Suboptimal response to COS might be related to ovarian sensitivity to exogenous gonadotropins modulated by genetic factors. The understanding of the gene polymorphisms related to reproductive function can help to improve the clinical management of this patient population and to explain some of the individual patient variability in response to COS. The development of a pharmacogenetic approach concerning COS in the context of assisted reproduction seems attractive as it might help to understand the relationship between genetic variants and ovarian response to exogenous gonadotropins. The patient's genetic profile could be used to select the most appropriate gonadotropin type, predict the optimal dosage for each drug, develop a cost-effective treatment plan, maximize the success rates, and lastly, decrease the time-to-pregnancy.

Ovarian Physiology and GWAS: Biobanks, Biology, and Beyond

Ovarian function is central to female fertility, and several genome-wide association studies (GWAS) have been carried out to elucidate the genetic background of traits and disorders that reflect and affect ovarian physiology. While GWAS have been successful in reporting numerous genetic associations and highlighting involved pathways relevant to reproductive aging, for ovarian disorders, such as premature ovarian insufficiency and polycystic ovary syndrome, research has lagged behind due to insufficient study sample size. Novel approaches to study design and analysis methods that help to fit GWAS findings into biological context will improve our knowledge about genetics governing ovarian function in fertility and disease, and provide input for clinical tools and better patient management.

The Ser680Asn polymorphism in the follicle-stimulating hormone receptor gene is associated with the ovarian response in controlled ovarian hyperstimulation

OBJECTIVE

Polymorphisms in the follicle-stimulating hormone receptor (FSHR) gene are reported to be associated with the ovarian response in controlled ovarian hyperstimulation (COH), although there remains some discordance between studies. Here, using the largest patient sample to date, we evaluated the association of the p.Ser680Asn (S(680)N) polymorphism in the FSHR gene with the outcome of COH.

DESIGN

Cohort study.

SETTING

Medical academy and hospital.

PATIENTS

A total of 1250 infertile Chinese women undergoing IVF/ICIS-ET treatment were included.

MEASURES

The association between an FSHR polymorphism (S(680)N) and the ovarian response was analysed. Genotyping was performed by utilizing direct sequencing and the Sequenom MassARRAY iPLEX platform. Follicular fluid oestradiol (E₂) and follicle-stimulating hormone (FSH) concentrations were determined using electrochemiluminesence immunoassays. The ovarian response parameters were analysed based on the FSHR genotypes. The odds ratios (ORs) and 95% confidence intervals (95% CIs) were calculated for the risk genotypes and alleles.

RESULTS

There were linear correlations between the basal FSH level, exogenous gonadotropin consumption, and oocytes retrieved and the Ser680 alleles. Patients in the homozygous SS group demonstrated higher basal FSH levels, required more dosage of exogenous gonadotropin for ovarian stimulation, and had fewer numbers of oocytes retrieved compared with patients in the homozygous NN and heterozygous groups. Logistic regression analysis revealed that the OR of a poor ovarian response for the NS genotype was 1·79 (95% CI 1·28-2·61; P < 0·001), whereas that for the SS genotype was 2·25 (95% CI 1·40-3·58; P < 0·001) after adjusting for age, BMI and basal FSH level. The concentration of E2 in the follicular fluid was significantly higher in subjects with the NN genotype than the SS genotype (772 ± 545 ng/ml vs. 1299 ± 504 ng/ml).

CONCLUSIONS

Follicle-stimulating hormone receptor gene polymorphism at position 680 is associated with different ovarian responses to controlled ovarian hyperstimulation.

Pharmacogenetics of ovarian response

Effective controlled ovarian stimulation (COS) is crucial for IVF outcome. Ovarian response to follicle-stimulating hormone, however, varies widely among women undergoing ovarian stimulation. Advance identification of patients who will elicit a poor or high response to standard treatment would be of great clinical benefit for such patients. Application of pharmacogenetics to ovarian response may predict stimulation success but also help in the adjustment and design of doses prior to treatment. Different studies have examined the impact of variations in follicle-stimulating hormone receptor, biochemical pathways involved in estrogen production and action, folliculogenesis and other aspects. Recently, gene-association studies have tried to identify a number of genetic variations affecting interindividual variability in COS.

Evaluating influence of the genotypes in the follicle-stimulating hormone receptor (FSHR) Ser680Asn (rs6166) polymorphism on poor and hyper-responders to ovarian stimulation: a meta-analysis

Background/aims

Reported associations of controlled ovarian hyperstimulation response (COH) with genotypes of the Ser680Asn (N680S) polymorphism in the follicle stimulating hormone receptor (FSHR) gene have conflicting results.

Methods

PubMed and Embase databases were searched for studies that investigated the N680S polymorphism in the FSHR gene in COH. Parameters used to examine ovarian response were poor and hyper-responses to COH. Using the meta-analytic approach, we estimated ovarian response risk (odds ratio [OR] with 95% confidence intervals) according to genotype.

Results

Our findings showed that SS genotype carriers were most likely to be poor responders (OR 1.61, p = 0.08) compared to the NN and NS genotypes which showed no associations (OR 0.93-0.95, p = 0.75-0.78). Heterogeneity of these pooled ORs warranted examining its sources. We detected outlying studies in each of the three N680S genotypes. Omitting these outliers erased the heterogeneity of the recalculated pooled outcomes. It also materially altered the SS effects where carriers became slightly unlikely to be poor responders (OR 0.90, p = 0.52). The S allele carrier effect was modulated for poor responders (OR 1.24, p = 0.39) in the Non-Hispanic Caucasian (NHC) subgroup. The likelihood of the S allele carriers (OR 1.47, p = 0.02) and the unlikelihood of the N allele carriers (OR 0.64, p = 0.007) were significant in our hyper-response findings. Confined to NHC retained significance of the S allele effects (OR 1.57, p = 0.01) but not among the N allele carriers (OR 0.68, p = 0.18).

Conclusions

In summary, this is a meta-analytical confirmation of the FSHR SS genotype role in COH response. Hyper-responder analysis strengths lie on the non-heterogeneity and robustness of its results. Non-robustness and heterogeneity of the poor-responder results compose its limitations. Thus, poor response findings probably require caution as to the interpretation as a susceptibility marker for ovarian response.

Electronic supplementary material

The online version of this article (doi:10.1186/s13048-014-0122-2) contains supplementary material, which is available to authorized users.

A single nucleotide polymorphism of bone morphogenic protein-15 is not associated with ovarian reserve or response to ovarian stimulation

STUDY QUESTION

Is there any effect of the -9C>G variant in the bone morphogenic protein-15 (BMP15) gene on ovarian response and/or current markers of ovarian reserve in patients undergoing in vitro fertilization (IVF) treatment?

SUMMARY ANSWER

No significant associations of BMP15 genotypes with ovarian response (number of oocytes retrieved) and/or markers of ovarian reserve were detected in our cohort of women undergoing IVF treatment.

WHAT IS KNOWN ALREADY

There is evidence that genetic variation influences patients' response to ovarian stimulation therapy. BMP15 plays a role in the recruitment of primordial follicles. Therefore, variation in BMP15 could predict ovarian reserve and response to ovarian stimulation. Two previous studies have determined a significant correlation between the BMP15 -9C>G variant and over-response to ovarian stimulation. No studies to date have correlated this variant with ovarian reserve markers.

STUDY DESIGN, SIZE, DURATION

In this prospective observational study, we genotyped the BMP15 -9C>G single nucleotide polymorphism in 239 unrelated women undergoing their first cycle of controlled ovarian stimulation for IVF and ICSI (intra-cytoplasmic sperm injection) using gonadotrophins at a tertiary referral centre for reproductive medicine between March 2009 and August 2010.

PARTICIPANTS/MATERIALS, SETTINGS, METHODS

Baseline pelvic ultrasound and blood tests were taken on Days 2-3 of the cycle for assessment of baseline hormones and for DNA extraction. Genotypes were determined using TaqMan allelic discrimination assay. Regression analysis was performed to assess the effect of the BMP15 genotype on the ovarian reserve markers, serum anti-Müllerian hormone (s-AMH), follicle stimulating hormone (s-FSH) and antral follicle count (AFC), with adjustment for age and body mass index (BMI), and on the primary outcomes of response (number of oocytes retrieved and gonadotrophin dose) with adjustment for age, BMI and treatment received.

MAIN RESULTS AND THE ROLE OF CHANCE

There was no evidence of any statistically significant (P < 0.05) difference in basal s-FSH, s-AMH and AFC between individuals with different BMP15 genotypes. The number of oocytes retrieved and gonadotrophin dose used were also comparable between the individuals with different genotypes.

LIMITATIONS, REASONS FOR CAUTION

A larger sample size would be required in order to determine if the BMP15 genotype has a small effect on ovarian reserve or response.

WIDER IMPLICATIONS OF THE FINDINGS

When considering the development of integrative clinical algorithms for individual FSH doses, our analysis suggests that the genotyping of BMP15 -9C>G does not provide additional useful information as a predictor of ovarian reserve or response to ovarian stimulation.

STUDY FUNDING/COMPETING INTERESTS

The study was funded by the Manchester Biomedical Research Centre. The authors have no competing interests to declare.

Variant-beta luteinizing hormone is not associated with poor ovarian response to controlled ovarian hyperstimulation

BACKGROUND

The most common genetic variant of luteinizing hormone (LH), variant-betaLH, has a different bioactivity than the wildtype. Carrying the variant allele was associated with an increased consumption of exogenous gonadotropin to achieve optimal ovarian response for in vitro fertilization procedures (IVF). The aim of this study was to examine if variant-betaLH was also more common in patients with a poor ovarian response to exogenous gonadotropin which negatively influenced treatment outcome.

FINDINGS

36 patients with poor ovarian response to ovarian stimulation for IVF and 98 controls with a normal response were genotyped for variant-betaLH using DNA sequencing. The carrier frequency in the control group was 17%. No association was found between poor ovarian response and variant-betaLH.

CONCLUSIONS

Testing patients for variant-betaLH prior to IVF is unlikely to predict poor ovarian response.

Gene polymorphisms in female reproduction

This chapter presents an overview of the gene polymorphisms underlying the functions of ovarian receptors and their clinical implications in the female fecundity. A selection of genetic studies revealing significant associations between receptor polymorphisms, gene mutations, and some pathological conditions (i.e., female infertility, premature ovarian failure, polycystic ovary syndrome, endometriosis) are reviewed.

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

PURPOSE

To investigate two of the most studied estrogen receptor alpha polymorphisms (PvuII and XbaI) in combination, in order to evaluate their impact on an ART program outcome.

METHODS

203 normally ovulating women who underwent IVF or ICSI treatment were genotyped for PvuII and XbaI polymorphisms in ESR1 intron 1 using Real-Time PCR. The relationship between the presence of polymorphic alleles and the ovulation induction parameters and outcome was examined.

RESULTS

Women were grouped according to the number of polymorphic alleles they carried in two groups (0-2 versus 3-4 polymorphic alleles). The presence of 3 or more polymorphic alleles was associated with significantly lower E2 levels on the day of hCG administration and a significantly lower rate of good quality embryos.

CONCLUSION

There is an association between ESR1 polymorphisms and some ART parameters such as the level of E2 on the day of hCG administration and the quality of the embryos. These results underline the importance of ESR1 as a candidate gene for the prediction of ovarian response to IVF/ICSI protocols. Future research work concerning several more genes is necessary for a better evaluation of patients before entering an IVF/ICSI program.

Increased risk of ovarian hyperstimulation syndrome following controlled ovarian hyperstimulation in patients with vascular endothelial growth factor +405 cc genotype

Ovarian hyperstimulation syndrome (OHSS) is a serious complication following controlled ovarian hyperstimulation (COH) for in vitro fertilization. OHSS has a range of clinical features from mild abdominal distention to severe thromboembolic events. Several clinical manifestations of OHSS such as ascites and hemoconcentration can be attributed to increased vascular permeability. Vascular endothelial growth factor (VEGF) and its receptor VEGFR2 have been identified as an important signaling system in mediating this increase. There is considerable genetic variation in the VEGF/R2 signaling system. We present the first study to examine if single nucleotide polymorphisms (SNPs) in the genes encoding the VEGF/R2 signaling system are associated with OHSS following COH. Blood samples from 53 OHSS patients and 100 controls were analyzed for six SNPs of interest. Odds ratios (OR) and 95% confidence intervals (95% CI) were estimated by a multivariate logistic regression model. We found an association between the VEGF +405cc genotype and OHSS (OR 3.4, 95% CI 1.01-11.7). This finding requires confirmation from other patient populations.

A common Asn680Ser polymorphism in the follicle-stimulating hormone receptor gene is not associated with ovarian response to gonadotropin stimulation in patients undergoing in vitro fertilization

OBJECTIVE

To assess the role of the variant p.Asn680Ser in the follicle-stimulating hormone receptor (FSHR) gene in determining ovarian response in patients undergoing in vitro fertilization (IVF) treatment.

DESIGN

Prospective observational study.

SETTING

Tertiary referral center for reproductive medicine.

PATIENT(S)

Women (n = 421) undergoing their first cycle of controlled ovarian stimulation for IVF and 83 healthy, ethnically matched controls.

INTERVENTION(S)

Baseline pelvic ultrasound and blood tests taken on days 2 to 3 of the cycle for assessment of baseline hormones and for DNA extraction.

MAIN OUTCOME MEASURE(S)

Genotypes for FSHR p.Asn680Ser determined using TaqMan allelic discrimination assay, and ovarian response to gonadotropin treatment classified as normal, poor, or overresponse based on the number of oocytes retrieved.

RESULT(S)

The FSHR p.Asn680Ser genotype frequencies were similar in IVF patients and controls. The number of oocytes retrieved was comparable between patients with different FSHR receptor genotypes. The total amount of gonadotropin used was also similar in all the genotype groups. A logistic regression analysis showed nonstatistically significant twofold difference in the distribution of genotypes between the groups with poor and normal ovarian response.

CONCLUSION(S)

The variant FSHR p.Asn680Ser was not shown to be predictive of ovarian response, but clinically relevant differences cannot be ruled out.

A chromosome 19 locus positively influences the number of retrieved oocytes during stimulated cycles in Brazilian women

PURPOSE

To evaluate if several genetic loci that are associated with variation in normal menopause age and early menopause can account for a poor response to controlled ovarian stimulation.

METHODS

A total of 71 patients age ≤35 years old who were undergoing intracytoplasmic sperm injection were genotyped for four genetic variants that are associated with normal variation in menopausal age and early menopause. The patients were divided into two groups based upon treatment response: a poor responder group (PR group, n = 21) and a normal responder group (NR group, n = 50). The genetic variants rs244715, rs9379896, rs4806660 and rs16991615 were analyzed.

RESULTS

There was no significant difference in the incidence of the genetic variants between the NR and PR group. The risk allele for the chromosome 19 variant (rs4806660) demonstrated a protective effect for a poor ovarian response. The presence of a risk allele was associated with an increased response to COS, which resulted in an elevated number of follicles (Coef: 2.54, P = 0.041) and retrieved oocytes (Coef: 1.41, P = 0.041).

CONCLUSIONS

The genetic variants rs244715, rs9379896, rs4806660 and rs16991615 are not risk factors for poor ovarian response in Brazilian women. In contrast, rs4806660 is associated with higher number of follicles and retrieved oocytes. rs4806660 may be associated with an increased response to gonadotrophin stimulation in this population.