Impact of gene polymorphisms of gonadotropins and their receptors on human reproductive success

Follicle-Stimulating Hormone Receptor and Estrogen Receptor Gene Polymorphisms in Women With Discordant Follicle-Stimulating Hormone and Anti-Mullerian Hormone Levels

Objective This study aimed to investigate follicle-stimulating hormone receptor (FSHR) polymorphisms (Thr307Ala and Asn680Ser), estrogen receptor 1 (ESR1) polymorphisms (PvuII and XbaI), and ESR2 polymorphisms (RsaI and AluI) in Turkish women with follicle-stimulating hormone (FSH) and anti-Mullerian hormone (AMH) discordance. Method Genotyping was performed in 60 patients aged 21-35 with FSH-AMH discordance and/or low ovarian reserve and 20 age-matched controls with normal FSH and AMH levels. The patients were investigated in four groups of 20 women according to their FSH and AMH levels. Groups 1, 2, 3, and 4 were as follows: normal FSH and low AMH levels, normal AMH and high FSH levels, high FSH and low AMH levels, and normal FSH and AMH levels. Genomic DNA was obtained from 3 cc peripheral blood, and polymorphisms were analyzed using TaqMan genotyping assays. Relations between groups of categorical variables were analyzed with a chi-square test. Differences between the groups were assessed using a student's t-test or Mann-Whitney U test. Results Women with discordant FSH and AMH levels (group 1 and group 2) were not statistically different from women with concordant FSH and AMH levels (group 3 and group 4) in terms of FSHR, ESR1, and ER2 single nucleotide polymorphisms (SNPs). Body mass index (BMI) was statistically significant between groups 1 and 2 as well as groups 2 and 3 (p = 0.004). Conclusions This study showed that FSHR, ESR1, and ESR2 SNPs have not had any effect on AMH-FSH discordance in reproductive age Turkish women.

APHRODITE criteria: addressing male patients with hypogonadism and/or infertility owing to altered idiopathic testicular function

RESEARCH QUESTION

Can a novel classification system of the infertile male - 'APHRODITE' (Addressing male Patients with Hypogonadism and/or infeRtility Owing to altereD, Idiopathic TEsticular function) - stratify different subgroups of male infertility to help scientists to design clinical trials on the hormonal treatment of male infertility, and clinicians to counsel and treat the endocrinological imbalances in men and, ultimately, increase the chances of natural and assisted conception?

DESIGN

A collaboration between andrologists, reproductive urologists and gynaecologists, with specialization in reproductive medicine and expertise in male infertility, led to the development of the APHRODITE criteria through an iterative consensus process based on clinical patient descriptions and the results of routine laboratory tests, including semen analysis and hormonal testing.

RESULTS

Five patient groups were delineated according to the APHRODITE criteria; (1) Hypogonadotrophic hypogonadism (acquired and congenital); (2) Idiopathic male infertility with lowered semen analysis parameters, normal serum FSH and normal serum total testosterone concentrations; (3) A hypogonadal state with lowered semen analysis parameters, normal FSH and reduced total testosterone concentrations; (4) Lowered semen analysis parameters, elevated FSH concentrations and reduced or normal total testosterone concentrations; and (5) Unexplained male infertility in the context of unexplained couple infertility.

CONCLUSION

The APHRODITE criteria offer a novel and standardized patient stratification system for male infertility independent of aetiology and/or altered spermatogenesis, facilitating communication among clinicians, researchers and patients to improve reproductive outcomes following hormonal therapy. APHRODITE is proposed as a basis for future trials of the hormonal treatment of male infertility.

Gonadotropins in the Management of Couple Infertility: Toward the Rational Use of an Empirical Therapy

Although epidemiology shows that both men and woman can experience infertility, the female partner usually experiences most of the diagnostic and therapeutic burden. Thus, management of couple infertility is a unique example of gender inequality. The use of exogenous gonadotropins in assisted reproductive technology (ART) to induce multifollicular growth is well consolidated in women, but the same is not done with the same level of confidence and purpose in infertile men. Indeed, the treatment of idiopathic male infertility is based on an empirical approach that involves administration of the follicle-stimulating hormone (FSH) in dosages within the replacement therapy range. This treatment has so far been attempted when the endogenous FSH serum levels are within the reference ranges. According to the most recent evidence, a "substitutive" FSH administration may not be effective enough, while a stimulatory approach could boost spermatogenesis over its basal levels without adverse extragonadal effects. This article aims to describe the rationale behind the empirical application of gonadotropins in couple infertility, highlighting the need for a change in the therapeutic approach, especially for the male partner.

Genetic Variants of Gonadotropins and Their Receptors Could Influence Controlled Ovarian Stimulation: IVF Data from a Prospective Multicenter Study

BACKGROUND

Specific polymorphisms might influence controlled ovarian stimulation in women undergoing assisted reproductive technologies (ARTs). Data regarding possible interactions of these polymorphisms are still scanty. The aim of this analysis was to evaluate the effect of polymorphisms of gonadotropins and their receptors in women undergoing ART.

METHODS

A total of 94 normogonadotropic patients from three public ART units were enrolled. Patients underwent a gonadotropin releasing hormone (GnRH) long down-regulation protocol with a starting dose of 150 IU of recombinant follicular stimulating hormone (FSH) daily. Eight polymorphisms were genotyped.

RESULTS

A total of 94 women (mean age 30.71 ± 2.61) were recruited. Fewer fertilized and mature oocytes were retrieved in homozygous carriers of luteinizing hormone/choriogonadotropin receptor (LHCGR) 291 (T/T) than in heterozygous C/T carriers (p = 0.035 and p = 0.05, respectively). In FSH receptor (FSHR) rs6165 and FSHR rs6166 carriers, the ratio between total gonadotropin consumption and number of oocytes retrieved differed significantly among three genotypes (p = 0.050), and the ratio was lower in homozygous A/A carriers than in homozygous G/G and heterozygous carriers. Women who co-expressed allele G in FSHR-29 rs1394205 and FSHR rs6166 and allele C LHCGR 291 rs12470652 are characterized by an increased ratio between total FSH dosage and number of oocytes collected after ovarian stimulation (risk ratio: 5.44, CI 95%: 3.18-7.71, p < 0.001).

CONCLUSIONS

Our study demonstrated that specific polymorphisms affect the response to ovarian stimulation. Despite this finding, more robust studies are required to establish the clinical utility of genotype analysis before ovarian stimulation.

Association Between Follicle-Stimulating Hormone Receptor (FSHR) rs6166 and Estrogen Receptor 1 (ESR1) rs2234693 Polymorphisms and Polycystic Ovary Syndrome Risk, Phenotype, and Reproductive Outcomes in an Infertile Portuguese Population

INTRODUCTION

Polycystic ovary syndrome (PCOS) is a common endocrine disorder often leading to anovulatory infertility. PCOS pathophysiology is still unclear and several potential genetic susceptibility factors have been proposed. The effect of polymorphisms in two genesrelated to follicular recruitment and development, the follicle-stimulating hormone receptor (FSHR) and the estrogen receptor 1 (ESR1), have been studied in different populations with contradictory results.

AIMS

To evaluate the influence of FSHR rs6166 (c.2039A>G) and of ESR1 rs2234693 (Pvull c.453-397 T > C) polymorphisms on PCOS risk, phenotype, and response to controlled ovarian stimulation (COS).

MATERIALS AND METHODS

Genotyping of the FSHR rs6166 and the ESR1 rs2234693 polymorphisms was performed in PCOS women and a control group undergoing in vitro fertilization (IVF). Demographic, clinical, and biochemical data, genotype frequency, and IVF outcomes were compared between groups.

RESULTS

We evaluated 88 PCOS women and 80 controls. There was no significant difference in the genotype distribution of FSHR rs6166 polymorphism between PCOS women and controls (AA 31.8%/AS 48.9%/SS 19.3% in PCOS women vs AA 37.5%/AS 40.0%/SS 22.5% in controls; p = 0.522). The same was true for the ESR1 rs2234693 (CC 24.1%/CT 46.0%/TT 29.9% in PCOS women vs CC 18.8%/CT 48.8%/TT 32.5% in controls; p = 0.697). In PCOS women, we found higher follicle-stimulating hormone (FSH) levels on the third day of the menstrual cycle associated with the SS variant of the FSHR polymorphism (9.2 vs 6.2 ± 1.6 and 5.6 ± 1.6 mUI/mL; p = 0.011). We did not find other associations between the baseline hormonal parameters, antral follicle count, and response measures to COS with FSHR or ESR1 genotypes. We found, however, a need for higher cumulative doses of FSH for COS in patients with the SS variant of the FSHR rs6166 polymorphism (1860.5 ± 627.8 IU for SSvs 1498.1 ± 359.3 for AA and 1425.4 ± 474.8 for SA; p = 0.046 and p = 0.046).

CONCLUSION

Our data suggest that in the population, FSHR rs6166and ESR1 rs2234693 polymorphisms do not influence the risk of developing PCOS nor do they influence the patient's phenotype and IVF success. However, the SS variant of the FSHR rs6166 polymorphism may be associated with FSH resistance requiring higher FSH doses for COS.

The Effect of the Allelics of Ser680Asn Polymorphisms of Follicle-Stimulating Hormone Receptor Gene in IVF/ICSI Cycles: a Systematic Review and Meta-analysis

A significant number of single-nucleotide polymorphisms (SNPs) of the follicle-stimulating hormone receptor (FSHr) can modify the response to exogenous FSH administration. A significant diversity in response to controlled ovarian stimulation (COS) in assisted reproductive technologies (ART) according to the type of allelic has been reported. We aimed to evaluate the relation between the Asn680Ser allelics and COS. A total of 4 electronic databases were searched for articles published up to August 2021. Prospective and retrospective comparative studies which reported outcomes after COS in patients who underwent genotyping for the detection of FSHr polymorphisms were considered eligible. A total of 11 studies including 4343 patients with Asn680Ser polymorphisms of the FSHr were included. Patients carrying the Asn/Asn allelic provide elevated E2 on the day of human chorionic gonadotropin (hCG) administration (1549 patients MD 262.39 pg/ml, p = 0.0007), but less transferrable embryos as compared with Ser/Ser genotype (283 patients MD - 0.11 embryos, p = 0.04). Ans/Ser versus Ser/Ser genotypes showed a higher E2 on the day of hCG administration (1799 patients, MD 207.86 pg/ml, p = 0.02). Pregnancy rates were similar in all combination of genotypes. There is currently no strong evidence suggesting that the examination of one gene in relation to genotypes can be effectively used as single tool to improve COS. However, polygenic analysis of different polymorphisms by analyzing the genetic profile of each individual could be useful. Further research is warranted to develop an algorithm that will enable simultaneous analysis of many genes, which combined with hormonal profile could promote treatment individualization.

Regulation of antral follicular growth by an interplay between gonadotropins and their receptors

Knowledge of the growth and maturation of human antral follicles is based mainly on concepts and deductions from clinical observations and animal models. To date, new experimental approaches and in vitro data contributed to a deep comprehension of gonadotropin receptors' functioning and may provide new insights into the mechanisms regulating still unclear physiological events. Among these, the production of androgen in the absence of proper LH levels, the programming of follicular atresia and dominance are some of the most intriguing. Starting from evolutionary issues at the basis of the gonadotropin receptor signal specificity, we draw a new hypothesis explaining the molecular mechanisms of the antral follicular growth, based on the modulation of endocrine signals by receptor-receptor interactions. The "heteromer hypothesis" explains how opposite death and life signals are delivered by gonadotropin receptors and other membrane partners, mediating steroidogenesis, apoptotic events, and the maturation of the dominant follicle.

Seasonal reproduction and gonadal function: A focus on humans starting from animal studies

Photoperiod impacts reproduction in many species of mammals. Mating occurs at specific seasons to achieve reproductive advantages, such as optimization of offspring survival. Light is the main regulator of these changes during the photoperiod. Seasonally breeding mammals detect and transduce light signals through extraocular photoreceptor, regulating downstream melatonin-dependent peripheral circadian events. In rodents, hormonal reduction and gonadal atrophy occur quickly, and consensually with short-day periods. It remains unclear whether photoperiod influences human reproduction. Seasonal fluctuations of sex hormones have been described in humans, although they seem to not imply adaptative seasonal pattern in human gonads. This review discusses current knowledge about seasonal changes in the gonadal function of vertebrates, including humans. The photoperiod-dependent regulation of hypothalamic-pituitary-gonadal axis, as well as morphological and functional changes of the gonads are evaluated herein. Endocrine and morphological variations of reproductive functions, in response to photoperiod, are of interest as they may reflect the nature of past population selection for adaptative mechanisms that occurred during evolution.

Recent advances in understanding gonadotropin signaling

Gonadotropins are glycoprotein sex hormones regulating development and reproduction and bind to specific G protein–coupled receptors expressed in the gonads. Their effects on multiple signaling cascades and intracellular events have recently been characterized using novel technological and scientific tools. The impact of allosteric modulators on gonadotropin signaling, the role of sugars linked to the hormone backbone, the detection of endosomal compartments supporting signaling modules, and the dissection of different effects mediated by these molecules are areas that have advanced significantly in the last decade. The classic view providing the exclusive activation of the cAMP/protein kinase A (PKA) and the steroidogenic pathway by these hormones has been expanded with the addition of novel signaling cascades as determined by high-resolution imaging techniques. These new findings provided new potential therapeutic applications. Despite these improvements, unanswered issues of gonadotropin physiology, such as the intrinsic pro-apoptotic potential to these hormones, the existence of receptors assembled as heteromers, and their expression in extragonadal tissues, remain to be studied. Elucidating these issues is a challenge for future research.

Morphological changes in mouse ovary due to hormonal hypersecretion and matrix metalloproteinase -2 activity

We analyzed whether aberrant gonadotropin secretion affects the morphological remodeling of murine ovarian tissues facilitated by activated matrix metalloproteinase (MMP) enzymes. Six mice were intraperitoneally injected with 5 IU of pregnant mare serum gonadotropin (PMSG) or human chorionic gonadotropin (HCG) every two days after estrus synchronization. Morphology and expression of various MMPs were assessed following the successful induction of hormonal secretion in these tissues. HCG treatment, but not PMSG treatment, resulted in the expanded production of granulose second follicular cells. In addition, the number of developing follicular cells in the HCG group increased compared with that in the PMSG group. Ovarian diameters were also very small in the PMSG group. Immunohistochemistry revealed decreased MMP-2 protein activity in the HCG group and increased MMP-2 activity in the PMSG group. Activity was particularly high in theca and granulose cells of the PMSG group, but only partial activity was observed in the theca cells of the HCG group. Vascular endothelial growth factor activity was increased in both the external and internal theca cell walls in the PMSG group while the HCG group showed high overall expression of this protein in the internal theca cells. These data indicate that follicular cell activity and remodeling of the ovaries differ based on the type of secretory hormone signals they receive. Inappropriate gonadotropin secretion may induce functional changes in the ovaries, and follicular remodeling may be facilitated by the activity of various MMPs.

Live birth achieved despite the absence of ejaculated spermatozoa and mature oocytes retrieved: a case report

The most common reason for in vitro fertilization (IVF) cycle cancelation is a lack of quality gametes available for intracytoplasmic sperm injection (ICSI). Here we present the successful fertility treatment of the couple affected by obstructive azoospermia combined with suboptimal response to controlled ovarian stimulation. Since the conventional approach appeared ineffective to overcome both partnersˈ specific problems, the targeted interventions, namely, (1) pharmacological enhancement of sperm motility and (2) polarized light microscopy (PLM)-guided optimization of ICSI time, were applied to rescue the cycle with only immature oocytes and immotile testicular sperm retrieved. The treatment with theophylline aided the selection of viable spermatozoa derived from cryopreserved testicular tissue. When the traditional stimulation protocol failed to produce mature eggs, non-invasive spindle imaging was employed to adjust the sperm injection time to the maturational stage of oocytes extruding a polar body in vitro. The fertilization of 12 late-maturing oocytes yielded 5 zygotes, which all developed into blastocysts. One embryo was transferred into the uterus on day 5 post-fertilization, and another 3 good quality blastocysts were vitrified for later use. The pregnancy resulted in a full-term delivery of a healthy child. This case demonstrates that the individualization beyond the standard IVF protocols should be considered to maximize the chance of poor-prognosis patients to achieve pregnancy with their own gametes.

Pharmacogenomic Biomarkers of Follicle-Stimulating Hormone Receptor Malfunction in Females with Impaired Ovarian Response-A Genetic Survey

Follicle-stimulating hormone receptor (FSHR) plays an essential role as one of the most important molecules in response to some of infertility related medications. Impaired ovarian reserve and poor response to such treatments are partially dependent on the FSHR molecule itself. However, the function and drug sensitivity for this receptor may change due to various allele and polymorphisms in the FSHR gene. Studies indicated some of the FSHR-mediated treatments utilized in clinical centers display different outcomes in specific populations, which may arise from FSHR altered genotypes in certain patients. To support the increased demands for reaching the personalized drug and hormone therapy in clinics, focusing on actionable variants through Pharmacogenomic analysis of this receptor may be necessary. The current study tries to display a perspective view on genetic assessments for Pharmacogenomic profiling of the FSHR gene via providing a systematic and critical overview on the genetics of FSHR and its diverse responses to ligands for infertility treatment in females with impaired ovarian responses and show the potential effects of the patient genetic make-up on related binding substances efficacy. All identified functional drug-related alleles were selected through a comprehensive literature search and analyzed. Advanced technologies for the genetic evaluation of them are also discussed properly.

FSH-R Human Early Male Genital Tract, Testicular Tumors and Sperm: Its Involvement in Testicular Disorders

The follicle-stimulating hormone receptor (FSH-R) expression was always considered human gonad-specific. The receptor has also been newly detected in extragonadal tissues. In this finding, we evaluated FSH-R expression in the human male early genital tract, in testicular tumors, and in sperm from healthy and varicocele patients. In sperm, we also studied the mechanism of FSH-R action. Immunohystochemistry and Western blot analysis showed FSH-R presence in the first pathways of the human genital tract, in embryonal carcinoma, and in sperm, but it was absent in seminoma and in lower varicocele. In sperm, FSH/FSH-R activity is mediated by G proteins activating the PKA pathway, as we observed by using the H89. It emerged that increasing FSH treatments induced motility, survival, capacitation, and acrosome reaction in both sperm samples. The different FSH-R expression in tumor testicular tissues may be discriminate by tumor histological type. In spermatozoa, FSH-R indicates a direct action of FSH in these cells, which could be beneficial during semen preparation for in vitro fertilization procedures. For instance, FSH positive effects could be relevant in idiopathic infertility and in the clinic surgery of varicocele. In conclusion, FSH-R expression may be considered a molecular marker of testicular disorders.

Research priorities in infertility and assisted reproductive technology treatments - a James Lind Alliance priority setting partnership with brazilian patients

OBJECTIVE

To identify the main research interests of Brazilian patients in the field of infertility and assisted reproductive technology (ART) treatments.

METHODS

This prospective multicenter cross-sectional study was carried out in Brazil. Patients attending five fertility centers from the Huntington Group between October and December 2018 were invited to join the study, which consisted of answering an anonymous survey online. Two hundred and twenty-seven patients signed the informed consent form and were emailed the survey link. The survey was designed based on the James Lind Alliance Priority Setting Partnership protocol. In the area of infertility, patients were probed on issues such as somatic and psychological effects of treatment, prevention, assisted reproductive technology (medications and procedures), success rates, risks, and emotional aspects.

RESULTS

The response rate (RR) was 47.58% (108 patients; 88 women - RR 51.46% and 20 men - RR 35.71%). Patient mean age was 36.5 years (SD 4.6). The top ten research priorities listed were 1) short- and long-term side effects of treatment; 2) how to cope with infertility; 3) risks associated with ART; 4) success rates in ART; 5) impact of diet on ART and fertility; 6) healthy habits; 7) alternative therapies; 8) impact of exercise on fertility and ART success; 9) oocyte quality and ovarian reserve; and 10) genetic or inherited causes of infertility.

CONCLUSION

To better cater to the needs of patients and develop patient-centered care in the field of infertility and ART treatment, clinicians, healthcare providers, and the scientific community must identify patient concerns and priorities and make efforts to address them.

Prospects for FSH Treatment of Male Infertility

CONTEXT

Despite the new opportunities provided by assisted reproductive technology (ART), male infertility treatment is far from being optimized. One possibility, based on pathophysiological evidence, is to stimulate spermatogenesis with gonadotropins.

EVIDENCE ACQUISITION

We conducted a comprehensive systematic PubMed literature review, up to January 2020, of studies evaluating the genetic basis of follicle-stimulating hormone (FSH) action, the role of FSH in spermatogenesis, and the effects of its administration in male infertility. Manuscripts evaluating the role of genetic polymorphisms and FSH administration in women undergoing ART were considered whenever relevant.

EVIDENCE SYNTHESIS

FSH treatment has been successfully used in hypogonadotropic hypogonadism, but with questionable results in idiopathic male infertility. A limitation of this approach is that treatment plans for male infertility have been borrowed from hypogonadism, without daring to overstimulate, as is done in women undergoing ART. FSH effectiveness depends not only on its serum levels, but also on individual genetic variants able to determine hormonal levels, activity, and receptor response. Single-nucleotide polymorphisms in the follicle-stimulating hormone subunit beta (FSHB) and follicle-stimulating hormone receptor (FSHR) genes have been described, with some of them affecting testicular volume and sperm output. The FSHR p.N680S and the FSHB -211G>T variants could be genetic markers to predict FSH response.

CONCLUSIONS

FSH may be helpful to increase sperm production in infertile men, even if the evidence to recommend the use of FSH in this setting is weak. Placebo-controlled clinical trials, considering the FSHB-FSHR haplotype, are needed to define the most effective dosage, the best treatment length, and the criteria to select candidate responder patients.

FSH for the Treatment of Male Infertility

Follicle-stimulating hormone (FSH) supports spermatogenesis acting via its receptor (FSHR), which activates trophic effects in gonadal Sertoli cells. These pathways are targeted by hormonal drugs used for clinical treatment of infertile men, mainly belonging to sub-groups defined as hypogonadotropic hypogonadism or idiopathic infertility. While, in the first case, fertility may be efficiently restored by specific treatments, such as pulsatile gonadotropin releasing hormone (GnRH) or choriogonadotropin (hCG) alone or in combination with FSH, less is known about the efficacy of FSH in supporting the treatment of male idiopathic infertility. This review focuses on the role of FSH in the clinical approach to male reproduction, addressing the state-of-the-art from the little data available and discussing the pharmacological evidence. New compounds, such as allosteric ligands, dually active, chimeric gonadotropins and immunoglobulins, may represent interesting avenues for future personalized, pharmacological approaches to male infertility.

Clinical relevance of genetic variants of gonadotrophins and their receptors in controlled ovarian stimulation: a systematic review and meta-analysis

BACKGROUND

Genotype has been implicated in the outcome of ovarian stimulation. The analysis of patient-specific genotypes might lead to an individualized pharmacogenomic approach to controlled ovarian stimulation (COS). However, the validity of such an approach remains to be established.

OBJECTIVE AND RATIONALE

To define the impact of specific genotype profiles of follicle-stimulating hormone, luteinizing hormone and their receptors (FSHR, LHR and LHCGR) on ovarian stimulation outcome. Specifically, our aim was to identify polymorphisms that could be useful in clinical practice, and those that need further clinical investigation.

SEARCH METHODS

A systematic review followed by a meta-analysis was performed according to the Cochrane Collaboration and Preferred Reporting Items for Systematic Reviews and Meta-analysis guidelines without time restriction. We searched the PubMed/MEDLINE, Cochrane Library, SCOPUS and EMBASE databases to identify all relevant studies published before January 2017. Only clinical trials published as full-text articles in peer-reviewed journals were included. The primary outcome was the number of oocytes retrieved.

OUTCOMES

Fifty-seven studies were assessed for eligibility, 33 of which were included in the qualitative and quantitative analyses. Data were independently extracted using quality indicators. COS outcomes related to seven polymorphisms (FSHR [rs6165], FSHR [rs6166], FSHR [rs1394205], LHB [rs1800447], LHB [rs1056917], LHCGR [rs2293275] and LHCGR [rs13405728]) were evaluated. More oocytes were retrieved from FSHR (rs6165) AA homozygotes (five studies, 677 patients, weighted mean difference [WMD]: 1.85, 95% CI: 0.85-2.85, P < 0.001; I2 = 0%) than from GG homozygotes and AG heterozygotes (four studies, 630 patients, WMD: 1.62, 95% CI: 0.28-2.95, P = 0.020; I2 = 56%). Moreover, stimulation duration was shorter in FSHR (rs6165) AA homozygotes than in AG carriers (three studies, 588 patients, WMD -0.48, 95% CI: -0.87 to -0.10, P = 0.010, I2 = 44%). A higher number of oocytes (21 studies, 2632 patients WMD: 0.84, 95% CI: 0.19 to 1.49, P = 0.01, I2 = 76%) and metaphase II oocytes (five studies, 608 patients, WMD: 1.03, 95% CI: 0.01-2.05, P = 0.050, I2 = 0%) was observed in AA than in GG homozygote carriers. FSH consumption was significantly lower in FSHR (rs1394205) GG homozygotes (three studies, 411 patients, WMD: -1294.61 IU, 95% CI: -593.08 to -1996.14 IU, P = 0.0003, I2 = 99%) and AG heterozygotes (three studies, 367 patients, WMD: -1014.36 IU, 95% CI: -364.11 to -1664.61 IU, P = 0.002, I2 = 99%) than in AA homozygotes.

WIDER IMPLICATIONS

These results support the clinical relevance of specific genotype profiles on reproductive outcome. Further studies are required to determine their application in a pharmacogenomic approach to ovarian stimulation.

Pharmacogenetics of FSH Action in the Female

The purpose of a pharmacogenomic approach is to tailor treatment on the basis of an individual human genotype. This strategy is becoming increasingly common in medicine, and important results have been obtained in oncologic and antimicrobial therapies. The rapid technological developments and availability of innovative methodologies have revealed the existence of numerous genotypes that can influence the action of medications and give rise to the idea that a true "individualized" approach could become in the future a reality in clinical practice. Moreover, compared to the past, genotype analyses are now more easily available at accessible cost. Concerning human reproduction, there is ample evidence that several variants of gonadotropins and their receptors influence female reproductive health and ovarian response to exogenous gonadotropins. In more detail, variants in genes of follicle-stimulating hormone β-chain (FSH-B) and its receptor (FSH-R) seem to be the most promising candidates for a pharmacogenomic approach to controlled ovarian stimulation in assisted reproductive technologies. In the present review, we summarize the evidence regarding FSH-B and FSH-R variants, with special reference to their impact on reproductive health and assisted reproductive technology treatments.

Molecular dynamics simulation of the follicle-stimulating hormone receptor. Understanding the conformational dynamics of receptor variants at positions N680 and D408 from in silico analysis

Follicle-stimulating hormone receptor (FSHR) is a G-protein coupled receptor (GPCR) and a prototype of the glycoprotein hormone receptors subfamily of GPCRs. Structural data of the FSHR ectodomain in complex with follicle-stimulating hormone suggests a "pull and lift" activation mechanism that triggers a conformational change on the seven α-helix transmembrane domain (TMD). To analyze the conformational changes of the FSHR TMD resulting from sequence variants associated with reproductive impairment in humans, we set up a computational approach combining helix modeling and molecular simulation methods to generate conformational ensembles of the receptor at room (300 K) and physiological (310 K) temperatures. We examined the receptor dynamics in an explicit membrane environment of polyunsaturated phospholipids and solvent water molecules. The analysis of the conformational dynamics of the functional (N680 and S680) and dysfunctional (mutations at D408) variants of the FSHR allowed us to validate the FSHR-TMD model. Functional variants display a concerted motion of flexible intracellular regions at TMD helices 5 and 6. Disruption of side chain interactions and conformational dynamics were detected upon mutation at D408 when replaced with alanine, arginine, or tyrosine. Dynamical network analysis confirmed that TMD helices 2 and 5 may share communication pathways in the functional FSHR variants, whereas no connectivity was detected in the dysfunctional mutants, indicating that the global dynamics of the FSHR was sensitive to mutations at amino acid residue 408, a key position apparently linked to misfolding and variable cell surface plasma membrane expression of FSHRs with distinct mutations at this position.

Frequency of the T307A, N680S, and -29G>A single-nucleotide polymorphisms in the follicle-stimulating hormone receptor in Mexican subjects of Hispanic ancestry

BACKGROUND

FSHR SNPs may influence the ovarian sensitivity to endogenous and exogenous FSH stimulation. Given the paucity of data on the FSHR c.919A > G, c.2039A > G and - 29G > A SNPs in Hispanic population, we here analyzed their frequency distribution in Mexican mestizo women.

METHODS

Samples from 224 Mexican mestizo women enrolled in an IVF program as well as a genotype database from 8182 Mexican mestizo subjects, were analyzed for FSHR SNPs at positions c.919, c.2039 and - 29G > A. Association between the genetic variants and reproductive outcomes was assessed.

RESULTS

The c.919 and c.2039 SNPs were in strong linkage disequilibrium and their corresponding genotype frequencies in the IVF group were: AA 46.8%, AG 44.2%, and GG 8.9%, and AA 41.9%, AG 48.2% and GG 9.8%, respectively. For the -29G > A SNP, genotype frequencies were 27% (GG), 50% (GA) and 23% (AA). In normal oocyte donors with the c.2039 GG genotype, the number of oocytes recovered after ovarian stimulation (COS) were significantly (p < 0.01) lower than in those bearing other genotypes in this or the -29G > A SNP. Analysis of the large scale database revealed that both allelic and genotype frequencies for the three SNPs were very similar to those detected in the IVF cohort (p ≥ 0.38) and that female carriers of the c.2039 G allele tended to present lower number of pregnancies than women bearing the AA genotype; this trend was stronger when women with more Native American ancestry was separately analyzed (OR = 2.0, C.I. 95% 1.03-3.90, p = 0.04). There were no differences or trends in the number of pregnancies among the different genotypes of the -29G > A SNP.

CONCLUSIONS

The frequency of the GG/GG combination genotype for the c.919 and c.2039 SNPs in Mexican hispanics is among the lowest reported. The GG genotype is associated with decreased number of oocytes recovered in response to COS as well as to lower pregnancy rates in Hispanic women from the general population. The absence of any effect of the -29AA genotype on the response to COS, indicates that there is no need to perform this particular genotype testing in Hispanic women with the purpose of providing an individually-tailored COS protocol.

Two Hormones for One Receptor: Evolution, Biochemistry, Actions, and Pathophysiology of LH and hCG

LH and chorionic gonadotropin (CG) are glycoproteins fundamental to sexual development and reproduction. Because they act on the same receptor (LHCGR), the general consensus has been that LH and human CG (hCG) are equivalent. However, separate evolution of LHβ and hCGβ subunits occurred in primates, resulting in two molecules sharing ~85% identity and regulating different physiological events. Pituitary, pulsatile LH production results in an ~90-minute half-life molecule targeting the gonads to regulate gametogenesis and androgen synthesis. Trophoblast hCG, the "pregnancy hormone," exists in several isoforms and glycosylation variants with long half-lives (hours) and angiogenic potential and acts on luteinized ovarian cells as progestational. The different molecular features of LH and hCG lead to hormone-specific LHCGR binding and intracellular signaling cascades. In ovarian cells, LH action is preferentially exerted through kinases, phosphorylated extracellular-regulated kinase 1/2 (pERK1/2) and phosphorylated AKT (also known as protein kinase B), resulting in irreplaceable proliferative/antiapoptotic signals and partial agonism on progesterone production in vitro. In contrast, hCG displays notable cAMP/protein kinase A (PKA)-mediated steroidogenic and proapoptotic potential, which is masked by estrogen action in vivo. In vitro data have been confirmed by a large data set from assisted reproduction, because the steroidogenic potential of hCG positively affects the number of retrieved oocytes, and LH affects the pregnancy rate (per oocyte number). Leydig cell in vitro exposure to hCG results in qualitatively similar cAMP/PKA and pERK1/2 activation compared with LH and testosterone. The supposed equivalence of LH and hCG has been disproved by such data, highlighting their sex-specific functions and thus deeming it an oversight caused by incomplete understanding of clinical data.

The gonadotropin system, lessons from animal models and clinical cases

This review article centers upon family of gonadotropin hormones which consists of two pituitary hormones - follicle-stimulating hormone (FSH) and luteinizing hormone (LH) as well as one non-pituitary hormone - human chorionic gonadotropin (hCG) secreted by placenta, and their receptors. Gonadotropins play an essential role in proper sexual development, puberty, gametogenesis, maintenance of pregnancy and male sexual differentiation during the fetal development. They belong to the family of glycoprotein hormones thus they constitute heterodimeric proteins built of common α subunit and hormone-specific β-subunit. Hitherto, several mutations in genes encoding both gonadotropins and their receptors have been identified in humans. Their occurrence resulted in a number of different phenotypes including delayed puberty, primary amenorrhea, hermaphroditism, infertility and hypogonadism. In order to understand the effects of mutations on the phenotype observed in affected patients, detailed molecular studies are required to map the relationship between the structure and function of gonadotropins and their receptors. Nonetheless, in vitro assays are often insufficient to understand physiology. Therefore, several animal models have been developed to unravel the physiological roles of gonadotropins and their receptors.

Pharmacogenetics of G-protein-coupled receptors variants: FSH receptor and infertility treatment

Infertility treatment may represent a paradigmatic example of precision medicine. Follicle-stimulating hormone (FSH) has been proposed as a valuable therapeutic option both in males and in females, even if a standardized approach is far to be established. To date, several genetic mutations as well as polymorphisms have been demonstrated to significantly affect the pathophysiology of FSH-FSH receptor (FSHR) interaction, although the underlying molecular mechanisms remain unclear. This review aims to highlight possible aspects of FSH therapy that could benefit from a pharmacogenetic approach, providing an up-to-date overview of the variability of the response to FSH treatment in both sexes. Specific sections are dedicated to the clinical use of FSH in infertility and how FSHR polymorphisms may affect the therapeutic endpoints.

Understanding Ovarian Hypo-Response to Exogenous Gonadotropin in Ovarian Stimulation and Its New Proposed Marker-The Follicle-To-Oocyte (FOI) Index

Hypo-responsiveness to controlled ovarian stimulation is an undervalued topic in reproductive medicine. This phenomenon manifests as a low follicles output rate (FORT) with a discrepancy between the relatively low number of pre-ovulatory follicles which develop following ovarian stimulation as compared to the number of antral follicles available at the start of stimulation. The pathophysiology mechanisms explaining the ovarian resistance to gonadotropin stimulation are not fully understood, but the fact that both hypo-responders and normal responders share similar phenotypic characteristics suggests a genotype-based mechanism. Indeed, existing evidence supports the association between specific gonadotropin and their receptor polymorphisms and ovarian hypo-response. Apart from genotypic trait, environmental contaminants and oxidative stress might also be involved in the hypo-response pathogenesis. The ratio between the number of oocytes collected at the ovum pick up and the number of antral follicles at the beginning of OS [Follicle to oocyte index (FOI)] is proposed as a novel parameter to assess the hypo-response. Compared with traditional ovarian reserve markers, FOI might reflect most optimally the dynamic nature of follicular growth in response to exogenous gonadotropin. In this review, we contextualize the role of FOI as a parameter to identify this condition, discuss the underlying mechanisms potentially implicated in the pathogenesis of hypo-response, and appraise possible the treatment strategies to overcome hyper-responsiveness to gonadotropin stimulation.

Human Chorionic Gonadotropin and Breast Cancer

Breast cancer is well known as a malignancy being strongly influenced by female steroids. Pregnancy is a protective factor against breast cancer. Human chorionic gonadotropin (HCG) is a candidate hormone which could mediate this antitumoral effect of pregnancy. For this review article, all original research articles on the role of HCG in breast cancer were considered, which are listed in PubMed database and were written in English. The role of HCG in breast cancer seems to be a paradox. Placental heterodimeric HCG acts as a protective agent by imprinting a permanent genomic signature of the mammary gland determining a refractory condition to malignant transformation which is characterized by cellular differentiation, apoptosis and growth inhibition. On the other hand, ectopic expression of β-HCG in various cancer entities is associated with poor prognosis due to its tumor-promoting function. Placental HCG and ectopically expressed β-HCG exert opposite effects on breast tumorigenesis. Therefore, mimicking pregnancy by treatment with HCG is suggested as a strategy for breast cancer prevention, whereas targeting β-HCG expressing tumor cells seems to be an option for breast cancer therapy.

Influence of gonadotropins on ovarian follicle growth and developmentin vivoandin vitro

Gonadotropins are the key regulators of ovarian follicles development. They are applied in therapeutic practice in assisted reproductive technology clinics. In the present review we discuss the basic gonadotropic hormones – recombinant human follicle-stimulating hormone, its derivatives, luteinizing hormone and gonadotropin serum of pregnant mares, their origin, and application in ovarian follicle systems inin vitroculture systems.

Genetics of gonadotropins and their receptors as markers of ovarian reserve and response in controlled ovarian stimulation

Several controlled ovarian stimulation (COS) protocols have been developed to increase the yield of mature oocytes retrieved in assisted reproductive techniques (ARTs). The ovarian reserve (OR) influences the COS response, and it represents the main parameter that helps clinicians in refining clinical treatments in the perspective of a "personalized" ART. This approach is even more needed in particular conditions such as poor OR or polycystic ovary syndrome. Follicle-stimulating hormone, luteinizing hormone, and human chorionic gonadotropin are currently used in COS at different combinations and with different efficacies, even if the best approach definition is controversial. Differences in individual-specific ovarian response to gonadotropin stimulation can be due to alterations of genes encoding for hormones or their receptors. In particular, FSHB c.-211G>T, FSHR p.Asn680Ser, and c.-29G>A SNP allelic combinations may be used as OR and COS response markers. The purpose of this review is to highlight the evidence-based relevance of mutations and polymorphisms in gonadotropins and their receptor genes as predictive markers of OR and COS response to achieve fine-tuned therapeutic regimens.