Absence of mutations in the coding regions of follicle-stimulating hormone receptor gene in Singapore Chinese women with premature ovarian failure and polycystic ovary syndrome

Genetic Variants of Steroidogenesis and Gonadotropin Pathways and Polycystic Ovary Syndrome Susceptibility: A Systematic Review and Meta-analysis

Genetic variants are predisposing factors to polycystic ovary syndrome (PCOS), a multifactorial condition that often gets triggered due to various environmental factors. The study investigates the association of the variants of genes that are involved in the steroidogenesis pathway or gonadotropin pathway with the risk of PCOS. Appropriate keywords for predetermined genes were used to search in PubMed, Google Scholar, Science Direct, and Central Cochrane Library up to January 11, 2023. PROSPERO (CRD42022275425). Inclusion criteria: (a) case-control study; (b) genotype or allelic data. Exclusion criteria were: (a) duplicate studies; (b) clinical trials, systematic reviews, meta-analysis or conference abstract, case reports; (c) other than the English language; (d) having insufficient data; e) genetic variants for which meta-analysis has been reported recently and does not have a scope of the update. Various genetic models were applied as per data availability. Overall 12 variants of 7 genes were selected for the analysis. Relevant data were extracted from 47 studies which include 10,584 PCOS subjects and 16,150 healthy controls. Meta-analysis indicates a significant association between TOX3 rs4784165 [ORs = 1.08, 95% CI (1.00-1.16)], HMGA2 rs2272046 [ORs = 2.73, 95% CI (1.97-3.78)], YAP1 rs1894116 [OR = 1.22, 95% CI (1.13-1.33)] and increased risk of PCOS. Whereas FSHR rs2268361 [ORs = 0.84, 95% CI (0.78-0.89)] is associated with decreased PCOS risk. When sensitivity analysis was carried out, the association became significant for CYP19 rs700519 and FSHR rs6165 under an additive model. In addition, C9Orf3 rs3802457 became significantly associated with decreased PCOS risk with the removal of one study. Insignificant association was observed for CYP19A (rs2470152), FSHR (rs2349415, rs6166), C9Orf3 (rs4385527), GnRH1 (rs6185) and risk of PCOS. Our findings suggest association of CYP19A (rs700519), TOX3 (rs4784165), HMGA2 (rs2272046), FSHR (rs6165, rs2268361), C9orf3 (rs3802457), and YAP1 (rs1894116) with risk for PCOS.

Polymorphisms in FSHR modulating susceptibility to polycystic ovary syndrome: an updated meta-analysis

BACKGROUND

Two polymorphisms, rs6165 and rs6166 located in the intracellular domain of FSHR has been reported to affect folliculogenesis, steroidogenesis and oocyte maturation. Several studies have highlighted the role of FSHR polymorphisms in PCOS but the findings are conflicting. A meta-analysis was carried out to decipher the emerging perspectives.

METHODOLOGY

A comprehensive literature search was made using PubMed, PCOSkb, and Google Scholar. New Ottawa Scale has been utilized to evaluate the quality of each article. To evaluate the strength of association under different genetic models of rs6165 and rs6166 polymorphisms, odds ratio with a 95% confidence interval (CI) was calculated.

RESULTS

A total of 20 articles were selected for the present study. In pooled analysis and after the stratification by ethnicity, polymorphism rs6165 remains unrelated to the onset of PCOS. Besides, rs6166 exhibits significant protection in the Indian population under recessive, additive, and allele models (OR = 0.7, CI: 0.54-0.9, p = 0.006, OR = 0.65, CI: 0.48-0.89, p = 0.006, OR = 0.82, CI: 0.7-0.95, p = 0.01, respectively) and low to moderate risk in the Caucasian population under allele model (OR = 1.17, CI: 1.04-1.32, p = 0.01).

CONCLUSION

This meta-analysis suggests that GG genotype of rs6166 provides protection against PCOS, in a population-specific manner.

Analyzing the Impact of FSHR Variants on Polycystic Ovary Syndrome-a Case-Control Study in Punjab

Polycystic ovary syndrome (PCOS) is an endocrine-metabolic syndrome that involves hyperandrogenism, menstrual irregularities, and/or small cysts in one or both ovaries which might lead to infertility in women. The genetics of PCOS is heterogenous with the involvement of several genes reported in the hypothalamic-pituitary-gonadal axis. Follicular growth and steroidogenesis regulation are both critically dependent on follicle-stimulating hormone (FSH). The variants of FSHR cause abnormal folliculogenesis, steroidogenesis, and oocyte maturation at various stages of growth and may render women more susceptible to PCOS development. The present case-control study evaluated the association of FSHR rs6165 and rs6166 variants with PCOS. A total of 743 females were recruited. PCR-RFLP method was used for the genotypic analysis of FSHR polymorphisms. Obesity was examined according to the categorization of body mass index (BMI) and waist-hip ratio (WHR). Biochemical analysis, including a lipid profile, LH, FSH, and testosterone levels, was done in both PCOS women and controls. BMI and WHR revealed a statistically significant difference between PCOS cases and controls. Overall, levels of HDL were significantly lower, whereas cholesterol, triglycerides, LDL, and VLDL levels were higher in PCOS women (p < 0.05). The genotypic and allelic frequencies of rs6165 and rs6166 did not demonstrate significant differences when PCOS women were compared with the control group. However, clinical features of PCOS including gonadotropic hormone (FSH), hyperandrogenism, and dyslipidemia were significantly correlated with variants of FSHR. The present study concludes that rs6165 and rs6166 were significantly related to clinical features of PCOS, regardless of providing direct disease risk.

Replication study and meta-analysis of selected genetic variants and polycystic ovary syndrome susceptibility in Asian population

PURPOSE

Polycystic ovary syndrome (PCOS) is a highly complex disorder influenced by genetic and environmental factors. Previous association studies have identified multiple PCOS-susceptible loci, but there is no consistent conclusion, which calls for further investigations.

METHODS

In the present case-control study, FSHR gene variants (rs2268361, rs6165, and rs6166), LHCGR gene variant (rs13405728), THADA gene variant (rs13429458), DENND1A gene variants (rs10818854 and rs2479106), and INSR gene variants (rs2059807 and rs1799817) were genotyped with Sanger sequencing in a total of 400 PCOS women and 480 healthy women.

RESULTS

After Bonferroni correction, our results showed that rs13405728, rs13429458, rs2479106, rs10818854, and rs2059807 were significantly associated with PCOS risk in Chinese women. To improve the statistical strength, a further meta-analysis in Asian population was conducted. Although rs6166 and rs1799817 were not associated with PCOS risk in the present study, they were identified to be strongly associated with PCOS risk in the pooled Koreans and Chinese respectively. No significant association with PCOS risk was consistently found for rs2268361 or rs6165. Moreover, the pooled results further confirmed the significant association with PCOS risk for rs13405728, rs13429458, rs2479106, rs10818854, and rs2059807.

CONCLUSIONS

Collectively, the rs6166, rs13405728, rs13429458, rs2479106, rs10818854, rs2059807, and rs1799817 may indeed be the genetic risk factors for PCOS in Asian population, which requires further investigation using larger independent sets of samples in different ethnic populations.

Variants Ala307Ala and Ser680Ser of 307 and 680 FSHr polymorphisms negatively influence on assisted reproductive techniques outcome and determine high probability of non-pregnancy in Caucasian patients

PURPOSE

To determine the influence of different genotypes of Ala307Thr and Asn680Ser FSHr polymorphisms on controlled ovarian stimulation (COS) outcome and pregnancy.

METHODS

This study collected blood and physiological and clinical parameters of 517 Caucasian patients (Statistical power ≥ 80%) that underwent COS treatment. Genotypes of Ala307Thr and Asn680Ser polymorphisms were determined using PCR amplification followed by Bsu36I and BsrI digestion, respectively.

RESULTS

Ala307Ala and Ser680Ser genotypes associated to worse parameters of COS outcome (preovulatory follicles P = 0.05, in both), justifying their lower pregnancy rate than Non-Ala307Ala, P = 0.01 and Non-Ser680Ser, P = 0.004, respectively or together, (P = 0.003). Within the Non-Ala307Ala group, Thr307Thr genotype showed higher number of fertilized oocytes (P = 0.04) and embryos (P = 0.01) than Non-Thr307Thr, but no influence on pregnancy rate. Ala307Ala and Ser680Ser patients doubled probability of non-pregnancy than Non-Ala307Ala (odds ratio = 2.0) and Non-Ser680Ser (odds ratio = 2.11), respectively. Ala307Ala and Ser680Ser genotypes tend to appear together (P < 0.0001), which increases the probability of non-pregnancy.

CONCLUSIONS

Ala307Ala and Ser680Ser genotypes of 307 and 680 FSHr polymorphisms associate to worse COS outcome than its respective Non-Ala307Ala and Non-Ser680Ser. Within the Non-Ala307Ala genotypes, Thr307Thr, although shows higher Fertilized Oocytes and Embryos, do not influence on pregnancy rate. Ala307Ala and Ser680Ser genotypes double the probability of Non-Pregnancy than their respective Non-Ala307Ala and Non-Ser680Ser genotypes. Furthermore, the strong tendency of these genotypes to appear together worsens the probability of pregnancy in these patients.

Phenotype and genotype of polycystic ovary syndrome in Asia: Ethnic differences

Polycystic ovary syndrome (PCOS) is a common endocrine disorder in reproductive-aged women, and ethnic diversity has been reported in its manifestation. This review addressed phenotype and genetic studies in Asian women with PCOS. Generally, East Asians are less hirsute, and the hirsutism score cutoff is lower than the Caucasian counterpart. It is not clear whether there are any significant differences in the prevalence or severity of irregular menstruation (IM) or characteristics of polycystic ovary (PCO) across ethnicities. Interestingly, the IM/PCO subgroup is a relatively common phenotype in East Asian patients but not in Caucasian patients. The prevalence of insulin resistance in PCOS patients varies depending on the index used and the cutoff, but women with PCOS showed a higher degree of insulin resistance than those of controls across ethnicities. Lower body mass index (BMI) and lower prevalence of metabolic syndrome were reported in East Asian patients, but despite lower BMI, a comparative study reported that Asian women with PCOS were more likely to have diabetes compared with Caucasian patients, suggesting they also have metabolic complications. Unlike East Asian patients, South Asian patients showed an increased degree of hirsutism, early onset of symptoms, and severe insulin resistance and metabolic risks compared with Caucasians. Genetic components play important roles in the pathogenesis of PCOS, and genome-wide association studies of PCOS suggest that similar genetic risk factors exist between Asian and Caucasian patients. Continuous comparative studies are needed to standardize the diagnosis and management of PCOS across different ethnicities.

The Genetics of Non-Syndromic Primary Ovarian Insufficiency: A Systematic Review

Several causes for primary ovarian insufficiency (POI) have been described, including iatrogenic and environmental factor, viral infections, chronic disease as well as genetic alterations. The aim of this review was to collect all the ge- netic mutations associated with non-syndromic POI. All studies, including gene screening, genome-wide study and as- sessing genetic mutations associated with POI, were included and analyzed in this systematic review. Syndromic POI and chromosomal abnormalities were not evaluated. Single gene perturbations, including genes on the X chromosome (such as BMP15, PGRMC1 and FMR1) and genes on autosomal chromosomes (such as GDF9, FIGLA, NOBOX, ESR1, FSHR and NANOS3) have a positive correlation with non-syndromic POI. Future strategies include linkage analysis of families with multiple affected members, array comparative genomic hybridization (CGH) for analysis of copy number variations, next generation sequencing technology and genome-wide data analysis. This review showed variability of the genetic factors associated with POI. These findings may help future genetic screening studies on large cohort of women.

Follicle Stimulating Hormone Receptor (FSHR) Polymorphisms and Polycystic Ovary Syndrome (PCOS)

Polycystic ovary syndrome (PCOS) is the commonest endocrine abnormality in women of reproductive age typically presenting with chronic oligo- or anovulation, clinical, or biochemical hyperandrogenism and polycystic ovarian morphology (PCOM). Restoring mono-ovulation is the ultimate goal of ovulation induction and most women do respond to ovulation inducing agents causing their Follicle-stimulating hormone (FSH) levels to rise. Familial clustering and the results from twin studies strongly support an underlying genetic basis for PCOS. Recent Genome wide association studies (GWAS) have identified several genetic variants being genome wide significantly associated with PCOS. Amongst those are variants in or near the Luteinizing hormone (LH) and FSH receptor genes as well as a variant in the FSH-β gene. The aim of this review is to summarize the available evidence as to whether single nucleotide polymorphisms are able to modify the PCOS phenotype or whether they constitute a risk factor for the syndrome. Data on the role of FSHR polymorphisms in PCOS are conflicting. It seems that in large Chinese studies FSHR polymorphisms are not associated with either PCOS risk or with PCOS treatment outcome. However, in large scale studies in Caucasians these polymorphisms seem to influence the risk of having PCOS. Moreover, these studies also showed that some polymorphisms might affect some clinical features of PCOS as well as treatment outcome. Although most research has focussed on the role of FSHR polymorphisms there seems to be also some evidence showing that single nucleotide polymorphisms (SNPs) in the LHCG-Receptor as well as those in FSH-β gene might also alter the phenotype of PCOS. In conclusion most studies confirm that FSHR polymorphisms do alter the phenotype of PCOS in that they either alter the response to exogenous FSH or hat they increase the risk of having PCOS.

Identification of selected genetic polymorphisms in polycystic ovary syndrome in Sri Lankan women using low cost genotyping techniques

Background

Polycystic ovary syndrome (PCOS), the commonest endocrine disorder affecting young women, appears to be a multigenic trait with contributing genes being unclear. Hence, analysis of polymorphisms in multiple candidate genes is required. Currently available genotyping methods are expensive, time-consuming with limited analytical sensitivity.

Aim

(i) Develop and validate high resolution melting (HRM) assay and allele-specific real-time quantitative PCR (AS-qPCR) for genotyping selected SNPs associated with PCOS.

(ii) Identify selected SNPs and their association with a Sri Lankan cohort of well-characterized PCOS.

Methods

DNA was extracted from women with well-characterized PCOS from adolescence (n = 55) and ethnically matched controls (n = 110). FTO (Fat mass and obesity associated gene; rs9939609), FSHB (Follicle stimulating hormone beta subunit; rs6169), FSHR (Follicle stimulating hormone receptor; rs6165/rs6166), and INSR (Insulin receptor; rs1799817) genes were genotyped using HRM assay. GnRH1 (Gonadotropin releasing hormone; rs6185), LHB (Luteinizing hormone beta subunit; rs1800447/rs34349826) and LHCGR (Luteinizing hormone/choriogonadotropin receptor; rs2293275) genes were genotyped using AS-qPCR method. Genotyping results were validated using Sanger sequencing.

Results

A significant association was observed within FTO gene polymorphism (rs9939609) and PCOS. Genotype frequency of FTO gene (rs9939609)—cases versus controls were TT-36.4% vs.65.4% (p<0.05), AT-23.6% vs.20.9%, AA-40% vs.13.6% (p<0.05). Genotype frequencies of the SNPs GnRH1 (rs6185), FSHB (rs6169), FSHR (rs6165 & rs6166), LHB (rs1800447 & rs34349826), LHCGR (rs2293275) and INSR (rs1799817) were not significantly different between cases and controls (p>0.05). Only the mutant alleles were observed for LHB rs1800447 and rs34349826 SNPs in both groups. The HRM and AS-qPCR assay results had 100% concordance with sequencing results.

Conclusions

FTO gene rs9939609 polymorphism is significantly more prevalent among Sri Lankan PCOS subjects while the other selected SNPs of HPG axis genes and INSR gene showed no association. HRM and AS-qPCR assays provide a reliable, fast and user-friendly genotyping method facilitating wider implication in clinical practice.

The impact of FSH receptor polymorphism on time-to-pregnancy: a cross-sectional single-centre study

Background

Single nucleotide polymorphism of the follicle-stimulating hormone (FSH) receptor (FSHR) is an important marker of ovarian function. However, its role in female fecundity remains debatable. The aim of the study to assess the relationship of FSHR polymorphism of Serine/Serine, Asparagine/Asparagine and Asparagine/Serine variants directly against the time-to-pregnancy (TTP) in women.

Methods

Data were collected from 291 consecutive selected post-partum Caucasians using this criterion: ethnicity, age between 21 and 34-year-old new mothers and, 0–3 days after delivery of newborns in the Klaipeda University Hospital, Lithuania. Questionnaires on factors associated with conception were given to patients, and blood samples were collected for genomic DNA extractions as well as for analysis of follicle-stimulating hormone receptor gene polymorphism. Odds ratios (OR) and 95% confidence intervals (CI) for time-to-pregnancy were estimated by multivariate logistic regression. Women with unplanned pregnancies and those who received assisted reproductive technologies were not included in the study.

Results

After adjustment for other possible factors, increased risk for time-to-pregnancy of 12 or more months was associated with: Serine/Serine polymorphism variant (OR = 1.38, 95% CI 1.56–2.71, p = 0.007), age of 30 or more years (OR = 1.95, 95% CI 1.25–2.71, p = 0.015), gynaecological diseases in the past (OR = 2.21, 95% CI 1.12–5.74, p = 0.027), prior contraception use (OR = 1.87, 95% CI 1.14–3.64, p = 0.016), and fertility problems in the past (OR = 1.57, 95% CI 1.16–4.76, p = 0.019).

Conclusion

The results suggest a possible relationship of FSH receptor gene Serine/Serine variant for the lower possibility of conception during the first 12 months of planned conception.

"Evaluation of four genes associated with primary ovarian insufficiency in a cohort of Mexican women"

PURPOSE

Primary ovarian insufficiency (POI) is a clinical condition observed in women younger than 40 years of age, characterized by amenorrhea, hypoestrogenism, high levels of follicle-stimulating hormone (FSH), and infertility. Mutations in some master regulators of the development, maturation, and maintenance of ovarian follicles such as BMP15, FSHR, FOXL2, and GDF9 have been suggested as etiological factors in the development of POI. The aim of this study, the first in the Mexican population, is to evaluate the presence of mutations or polymorphisms in these four candidate genes.

METHODS

In a sample of 20 Mexican patients with idiopathic POI, we looked for and analyzed genetic variants in BMP15, FSHR, FOXL2, and GDF9 genes.

RESULTS

We observed two polymorphisms: a coding change, c.919G>A (p.Ala307Thr), in the FSHR gene and a synonymous variant, c.447C>T (p.Thr149Thr), in the GDF9 gene. These two variants have been reported previously as polymorphisms (rs6165 and rs254286, respectively). We observed no significant difference associated with POI in the patients when compared with a healthy control group (p > 0.05). Also, no exonic variants were found for the genes BMP15 and FOXL2 in the individuals tested.

CONCLUSIONS

The lack of association of the evaluated genes in this sample of Mexican women is consistent with the complex genetic etiology of POI that is observed across cohorts studied thus far.

The Impact of Genetic Variation and Gene Expression Level of The Follicle-Stimulating Hormone Receptor on Ovarian Reserve

OBJECTIVES

Ovarian reserve is defined as the capacity of the ovary to provide fertile oocytes. Diminished ovarian reserve (DOR) is a disorder in which ovaries are prone to go through early menopause. Where this loss of function occurs before the age of 40, it results in the premature ovarian failure (POF) disease. Throughout folliculogenesis, the follicle-stimulating hormone receptor (FSHR) starts a signaling cascade in the granulosa cells where its inactivation leads to the arrest of follicle maturation and therefore adversely affects ovarian reserve. The aim of this study was to investigate the association of genetic variation (polymorphisms and inactivating mutations) of FSHR with POF and DOR.

MATERIALS AND METHODS

This case-control study comprised 84 POF, 52 DOR and 80 fertile Iranian women. To determine the presence of the 566C>T mutation and the -29G>A polymorphism in FSHR, PCR-RFLP method was used. SSCP-sequencing was used to identify any allelic variants in exon 10. The expression of human FSHR at the transcript level was also compared between DOR and fertile controls by real time-polymerase chain reaction (PCR).

RESULTS

The 566C>T polymorphism was normal in all the cases. All genotypes of -29G>A and 919G>A (exon 10) polymorphisms were observed. Statistically significant differences were seen in the genotypic distribution of both polymorphisms when comparing the control group with the DOR patient group. A decrease was observed in FSHR expression of DOR patients compared with the control group but was not significant.

CONCLUSIONS

We conclude that the -29G>A and 919G>A polymorphisms in FSHR may be associated with DOR. Although these polymorphisms had significant differences at the genic level, no significant variation was found at the transcript level.

FSH receptor gene p. Thr307Ala and p. Asn680Ser polymorphisms are associated with the risk of polycystic ovary syndrome

PURPOSE

The purpose of this study was to investigate whether the follicle-stimulating hormone receptor (FSHR) gene p. Thr307Ala (c.919A>G, rs6165) and p. Asn680Ser (c.2039A>G, rs6166) polymorphisms are associated with susceptibility to polycystic ovary syndrome (PCOS).

METHODS

Genotyping was performed in 377 women with PCOS and 388 age-matched controls. Difference in the genotype distribution was assessed using a Fisher's exact or chi-square test, and continuous variables were compared using a Student's t test. To evaluate the association between the presence of PCOS status and SNP, logistic regression analyses were performed.

RESULTS

Linkage disequilibrium between the two polymorphisms was approximately complete (r ² = 99%). The genotype distributions of the PCOS group significantly differed from those of the control group (Thr/Thr, Thr/Ala, and Ala/Ala frequencies were 38.5, 46.7, and 14.9% for the PCOS group and 46.6, 45.4, and 8.0% for the controls, respectively, P = .005; Asn/Asn, Asn/Ser, and Ser/Ser frequencies were 39.5, 47.2, and 13.3% for the PCOS group and 46.4, 45.4, and 8.2% for the controls, respectively, P = .035). Using the wild-type genotypes as the references, the odds ratios that a woman has PCOS were 2.23 (95% confidence intervals 1.38-3.68) for the Ala/Ala genotype, 1.87 (95% confidence intervals 1.14-3.06) for the Ser/Ser genotype, and 1.96 (95% confidence intervals 1.19-3.24) for the homozygous variant combination (Ser/Ser-Ala/Ala). However, there were no significant differences in serum hormonal, ovarian, and metabolic markers according to each genotype.

CONCLUSIONS

Findings of this study suggest a significant association between FSHR gene p. Thr307Ala or p. Asn680Ser coding sequence change and PCOS. The variant homozygote genotype results in a higher risk of PCOS.

Genetics of primary ovarian insufficiency: new developments and opportunities

BACKGROUND

Primary ovarian insufficiency (POI) is characterized by marked heterogeneity, but with a significant genetic contribution. Identifying exact causative genes has been challenging, with many discoveries not replicated. It is timely to take stock of the field, outlining the progress made, framing the controversies and anticipating future directions in elucidating the genetics of POI.

METHODS

A search for original articles published up to May 2015 was performed using PubMed and Google Scholar, identifying studies on the genetic etiology of POI. Studies were included if chromosomal analysis, candidate gene screening and a genome-wide study were conducted. Articles identified were restricted to English language full-text papers.

RESULTS

Chromosomal abnormalities have long been recognized as a frequent cause of POI, with a currently estimated prevalence of 10-13%. Using the traditional karyotype methodology, monosomy X, mosaicism, X chromosome deletions and rearrangements, X-autosome translocations, and isochromosomes have been detected. Based on candidate gene studies, single gene perturbations unequivocally having a deleterious effect in at least one population include Bone morphogenetic protein 15 (BMP15), Progesterone receptor membrane component 1 (PGRMC1), and Fragile X mental retardation 1 (FMR1) premutation on the X chromosome; Growth differentiation factor 9 (GDF9), Folliculogenesis specific bHLH transcription factor (FIGLA), Newborn ovary homeobox gene (NOBOX), Nuclear receptor subfamily 5, group A, member 1 (NR5A1) and Nanos homolog 3 (NANOS3) seem likely as well, but mostly being found in no more than 1-2% of a single population studied. Whole genome approaches have utilized genome-wide association studies (GWAS) to reveal loci not predicted on the basis of a candidate gene, but it remains difficult to locate causative genes and susceptible loci were not always replicated. Cytogenomic methods (array CGH) have identified other regions of interest but studies have not shown consistent results, the resolution of arrays has varied and replication is uncommon. Whole-exome sequencing in non-syndromic POI kindreds has only recently begun, revealing mutations in the Stromal antigen 3 (STAG3), Synaptonemal complex central element 1 (SYCE1), minichromosome maintenance complex component 8 and 9 (MCM8, MCM9) and ATP-dependent DNA helicase homolog (HFM1) genes. Given the slow progress in candidate-gene analysis and relatively small sample sizes available for GWAS, family-based whole exome and whole genome sequencing appear to be the most promising approaches for detecting potential genes responsible for POI.

CONCLUSION

Taken together, the cytogenetic, cytogenomic (array CGH) and exome sequencing approaches have revealed a genetic causation in ∼20-25% of POI cases. Uncovering the remainder of the causative genes will be facilitated not only by whole genome approaches involving larger cohorts in multiple populations but also incorporating environmental exposures and exploring signaling pathways in intragenic and intergenic regions that point to perturbations in regulatory genes and networks.

Family-based analysis of eight susceptibility loci in polycystic ovary syndrome

Polycystic ovary syndrome (PCOS) is a complex endocrine disorder that is proposed to have a genetic basis. A recent genome-wide association study (GWAS) identified eight new risk loci that are independently associated with PCOS. To further validate the findings, a total of 321 case-parent trios (963 participants) who had a proband affected with PCOS were recruited for the family-based study. The transmission disequilibrium test (TDT) was used to analyze associations between PCOS and ten single nucleotide polymorphisms (SNPs) mapped to eight new susceptibility loci. Significant differences in transmission were observed for the SNPs rs2349415 (located in the FSHR gene, P = 0.0001) and rs3802457 (located in the C9orf3 gene, P = 0.0001), even after correction for multiple testing bias. The present data provides further evidence for an association between two susceptibility loci, 2p16.3 and 9q22.32, and PCOS. Follow-up functional studies on the FSHR and C9orf3 genes are required to understand their roles in PCOS development.

Association between two polymorphisms of follicle stimulating hormone receptor gene and susceptibility to polycystic ovary syndrome: a meta-analysis

OBJECTIVE

To investigate the association between two polymorphisms of follicle stimulating hormone receptor (FSHR) gene and polycystic ovary syndrome (PCOS) susceptibility.

METHODS

Case-control studies on relationship of Thr307Ala and Asn680Ser polymorphisms in FSHR gene and PCOS susceptibility were searched from PubMed, ISI web of knowledge, EBSCO, and China National Knowledge Infrastructure (CNKI) databases up to March 21, 2013. The pooled odds ratio (OR) and 95% confidence interval (CI) were calculated using fixed- or random-effect model based on heterogeneity test in 5 genotype models analyses.

RESULTS

A total of 11 studies were included in the Meta-analysis. The random-effect analysis showed Asn680Ser was significantly associated with the reduced susceptibility to PCOS with dominant model (Asn/Asn+Asn/Ser vs. Ser/Ser, OR=0.83, 95% CI: 0.69-1.00), recessive model (Asn/Asn vs. Asn/Ser+ Ser/Ser, OR=0.84, 95% CI: 0.72-0.98), homozygote comparison (Asn/Asn vs. Ser/Ser, OR=0.79, 95% CI: 0.63-0.98), and the allele contrast (Asn vs. Ser, OR=0.87, 95% CI: 0.79-0.97) respectively(P=0.02, I(2)=56.0%), being protective factors for PCOS. However, no significant associations were found between Thr307Ala and PCOS.

CONCLUSION

There might be a significant association between Asn680Ser polymorphism and PCOS.

Are FSHR polymorphisms risk factors to premature ovarian insufficiency?

Premature ovarian insufficiency (POI) is an ovarian dysfunction characterized by increased FSH levels and amenorrhea before 40 years old. In recent years, the search for genetic causes of POI intensified and studies have been published relating the presence of mutations and polymorphisms in genes associated with development, recruitment and oocyte atresia. The aim of this study was to evaluate the presence of FSHR polymorphisms in our population and contribute with the elucidation of POI etiology. To achieve it, we have studied 100 patients with POI (G1), 60 patients with border line levels of FSH (G2) and 123 controls with regular menopause onset. Cytogenetic analysis of patients' samples and genotyping of Asn680Ser and Ala307Thr polymorphisms were performed in cases and controls. Cytogenetic analysis showed that 92% of G1 patients had normal karyotype, 4% presented polymorphic variants, 3% presented mosaic karyotype involving X chromosome. In G2, 91.6% had normal karyotype results, 3.2% displayed polymorphic variants, and 3.3% presented a mosaic karyotype involving X chromosome. Statistical comparison showed that the polymorphic allele of Ala307Thr polymorphism is more frequent in patients than in controls (G1: p < 0.001 and G2: p = 0.0259). This association has not been previously reported. We concluded that Ala307Thr polymorphism in FSHR can be potentially associated to POI development and can be considered as a screening marker in patients with ovarian failure signals.

New insights into the genetic basis of infertility

Infertility is a disease of the reproductive system characterized by inability to achieve pregnancy after 12 or more months of regular unprotected sexual intercourse. A variety of factors, including ovulation defects, spermatogenic failure, parental age, obesity, and infections have been linked with infertility, in addition to specific karyotypes and genotypes. The study of genes associated with infertility in rodent models has expanded the field of translational genetics in identifying the underlying cause of human infertility problems. Many intriguing aspects of the molecular basis of infertility in humans remain poorly understood; however, application of genetic knowledge in this field looks promising. The growing literature on the genetics of human infertility disorders deserves attention and a critical concise summary is required. This paper provides information obtained from a systematic analysis of the literature related to current research into the genetics of infertility affecting both sexes.

Follicle-stimulating hormone receptor gene polymorphism in chronic anovulatory women, with or without polycystic ovary syndrome: a cross-sectional study

BACKGROUND

Polymorphisms at codons 307 and 680 are the most commonly encountered allelic variants of the follicle-stimulating hormone receptor (FSHR) gene. Studies in Caucasians suggest that certain FSHR variants are more common in women with polycystic ovary syndrome (PCOS) than normal women. The objective of this study was to determine the distribution of FSHR gene polymorphisms at codons 307 and 680 in Thai women with chronic anovulation, without (121 women) and with PCOS (133 women), using 132 known fertile women as controls.

METHODS

DNA samples from peripheral blood lymphocytes were extracted and analyzed by polymerase chain reaction-restriction fragment length polymorphism.

RESULTS

The prevalence of Threonine307Threonine (TT), Threonine307Alanine (TA), and Alanine307Alanine (AA) genotypes at codon 307 was 53.0% (95% CI = 44.2-61.7%), 42.4% (95% CI = 34-51.3%), and 4.5% (95% CI = 1.9-10.1%) in controls; 52.6% (95% CI = 43.8-61.3%), 39.8% (95% CI = 31.6-48.7%), and 7.5% (95% CI = 3.9-13.7%) in PCOS women; and 50.4% (95% CI = 42.8-61.2%), 45.4% (95% CI = 34.9-53.1%), and 4.5% (95% CI = 1.5-9.6%) in anovulatory women without PCOS, respectively. The prevalence of Asparagine680Asparagine (NN), Asparagine680Serine (NS), and Serine680Serine (SS) genotypes at codon 680 was 54.5% (95% CI = 45.7-63.2%), 40.9% (95% CI = 32.5-49.8%), and 4.5% (95% CI = 1.9-10.1%) in controls; 51.9% (95% CI = 43.1-60.6%), 44.4% (95% CI = 35.8-53.2%), and 3.8% (95% CI = 1.4-9.0%) in PCOS women; and 47.9% (95% CI = 40.4-58.8%), 47.1% (95% CI = 36.5-54.7%), and 5.0% (95% CI = 2-10.9%) in anovulatory women without PCOS, respectively. The prevalence of FSHR gene polymorphisms at both codons were not statistically different among the three groups.

CONCLUSIONS

In Thai women, there was no association between the FSHR gene polymorphism at codons 307 and 680 and chronic anovulation.

Two follicle-stimulating hormone receptor polymorphisms and polycystic ovary syndrome risk: a meta-analysis

The aim of this study was to explore the association between follicle stimulating hormone receptor (FSHR) Thr307Ala and Asn680Ser polymorphisms and susceptibility to polycystic ovary syndrome (PCOS). A comprehensive literature search for relevant studies was conducted on Google Scholar, PubMed, the Chinese National Knowledge Infrastructure (CNKI) and the Chinese Biomedical Literature Database (CBM). This meta-analysis was performed using the STATA 11.0 software and the pooled odds ratio (OR) with 95% confidence interval (CI) was calculated. Ten case-control studies were included in this meta-analysis. However, meta-analysis results showed no association between both FSHR Thr307Ala polymorphism and Asn680Ser polymorphism and susceptibility to PCOS. Stratified analysis of ethnicities also showed no association. In conclusion, the present study suggested that the FSHR polymorphisms were not associated with an increased risk of PCOS and larger-scale studies of populations are needed to explore the roles played by FSHR polymorphisms during the pathogenesis of PCOS.

Genetic association studies in female reproduction: from candidate-gene approaches to genome-wide mapping

Many genetic association studies have been performed to investigate disorders of female reproduction, such as polycystic ovary syndrome, premature ovarian failure and endometriosis. These disorders typically manifest heterogeneously, and their pathogeneses are influenced by polygenic and environmental factors. Researchers evaluating these genetic associations have chosen candidate genes related to hormone action, steroid biosynthesis, inflammatory cytokines and autoimmune factors. Several of these genes have yielded statistically significant associations with female reproductive disorders; however, few associations have been robust and reproducible. Whole-genome association studies generate more reliable and unbiased results and represent a breakthrough in genetic studies of female reproduction. Nevertheless, to date only a very small fraction of the overall heritability has been identified and so further studies are needed.

Polymorphisms in gonadotropin and gonadotropin receptor genes as markers of ovarian reserve and response in in vitro fertilization

Since gonadotropins are the fundamental hormones that control ovarian activity, genetic polymorphisms may alter gonadal responsiveness to glycoproteins; hence they are important regulators of hormone activity at the target level. The establishment of the pool of primordial follicles takes place during fetal life and is mainly under genetic control. Consequently, single nucleotide polymorphisms (SNPs) in gonadotropins and their receptors do not seem to be associated with any significant modification in the endowment of nongrowing follicles in the ovary. Indeed, the age at menopause, a biological characteristic strongly related to ovarian reserve, as well as markers of functional ovarian reserve such as anti-Müllerian hormone and antral follicle count, are not different in women with different genetic variants. Conversely, some polymorphisms in FSH receptor (FSHR) seem to be associated with modifications in ovarian activity. In particular, studies suggest that the Ser680 genotype for FSHR is a factor of relative resistance to FSH stimulation resulting in slightly higher FSH serum levels, thus leading to a prolonged duration of the menstrual cycle. Moreover, some FSHR gene polymorphisms show a positive association with ovarian response to exogenous gonadotropin administration, hence exhibiting some potential for a pharmacogenetic estimation of the FSH dosage in controlled ovarian stimulation. The study of SNPs of the FSHR gene is an interesting field of research that could provide us with new information about the way each woman responds to exogenous gonadotropin administration during ovulation induction.

FSH receptor gene variants are rarely associated with premature ovarian failure

FSH receptor (FSHR) gene variants have been associated with premature ovarian failure (POF). Genomic DNA from New Zealand women with POF (n=80) and control women (n=80) was screened for variants in FSHR exons 7 and 10. FSHR exon 7 variants, including the c.566C>T Finnish founder mutation (p.Ala189Val), were not detected. Previously reported FSHR exon 10 polymorphisms were identified in both groups with similar allelic distributions. A novel heterozygous FSHR exon 10 variant c.1411A>T, p.Ile471Phe was observed in one woman with a family history of POF, but not her affected siblings. It is concluded that variants in exons 7 and 10 of FSHR are not frequently associated with the development of POF in the New Zealand population.

Effects of polymorphisms in gonadotropin and gonadotropin receptor genes on reproductive function

Gonadotropins, the action of which is mediated at the level of their gonadal receptors, play a key role in sexual development, reproductive functions and in metabolism. The involvement of the gonadotropins and their receptor genotypes on reproductive function are widely studied. A large number of gonadotropins and their receptors gene polymorphisms are known, but the only one considerable as a clear, absolute genetic marker of reproductive features or disfunctions is the FSHR Asn680Ser polymorphism, since it modulates ovarian response to FSH. The aim of these studies would to be the prediction of the genetic causes of sex-related diseases to enable a customized clinical setting based on individual response of patients undergoing gonadotropin stimulation. In this review we discuss the latest information about the effects of polymorphisms of the gonadotropins and their receptor genes on reproductive functions of both male and female, and discuss their patho-physiological implications.

Mutational analysis of human bone morphogenetic protein 15 in Chinese women with polycystic ovary syndrome

Polycystic ovary syndrome (PCOS) is one of the common defects that cause ovary dysfunction and link to the aberrant process of folliculogenesis. Bone morphogenetic protein 15 (BMP15) is expressed in human oocytes and functions importantly to regulate early follicle growth and fertility. Previous studies have discovered several mutations in the screening of BMP15 in premature ovarian failure but none in PCOS. In this current study, we focused on the mutational analysis of the coding region of BMP15 among 216 Chinese PCOS patients. Five novel missense mutations in BMP15 were discovered, namely, c.34C>G, c.109G>C, c.169C>G, c.288G>C, and c.598C>T. These results are the first to indicate that BMP15 gene mutations may be potentially associated with PCOS patients.

Genome-wide association study identifies susceptibility loci for polycystic ovary syndrome on chromosome 2p16.3, 2p21 and 9q33.3

Polycystic ovary syndrome (PCOS) is a common metabolic disorder in women. To identify causative genes, we conducted a genome-wide association study (GWAS) of PCOS in Han Chinese. The discovery set included 744 PCOS cases and 895 controls; subsequent replications involved two independent cohorts (2,840 PCOS cases and 5,012 controls from northern Han Chinese; 498 cases and 780 controls from southern and central Han Chinese). We identified strong evidence of associations between PCOS and three loci: 2p16.3 (rs13405728; combined P-value by meta-analysis P(meta) = 7.55 × 10⁻²¹, odds ratio (OR) 0.71); 2p21 (rs13429458, P(meta) = 1.73 × 10⁻²³, OR 0.67); and 9q33.3 (rs2479106, P(meta) = 8.12 × 10⁻¹⁹, OR 1.34). These findings provide new insight into the pathogenesis of PCOS. Follow-up studies of the candidate genes in these regions are recommended.

Identification of novel missense mutations of GDF9 in Chinese women with polycystic ovary syndrome

The gene for growth differentiation factor 9 (GDF9) is expressed in human oocytes and has an important function in regulating early follicle growth and fertility. Polycystic ovary syndrome (PCOS) is one of the common defects that causes ovary dysfunction and is linked to aberrant processes in folliculogenesis. Previous studies have discovered several mutations in the screening of GDF9 in premature ovarian failure but none in PCOS. This current study focused on the mutational analysis of the coding region of GDF9 among 216 Chinese PCOS patients. Of the 10 different variants found in this study, five novel missense mutations in GDF9 were discovered namely c.15C>G, c.118T>G, c.133A>G, c.1025A>T and c.1275C>A. The above-mentioned mutations indicate GDF9 may be potentially associated with PCOS patients. As far as is known, this study is the first to provide evidence for such an association.

Follicle stimulating hormone receptor gene variants in women with primary and secondary amenorrhea

PURPOSE

This retrospective study was designed to analyze the FSHR gene variants in subjects with primary and secondary amenorrhea with hypergonadotropic hypogonadism.

MATERIALS AND METHODS

Eighty six women with primary or secondary amenorrhea and 100 normally cycling proven fertile women of Indian origin were retrospectively studied. These subjects were systematically screened for entire FSHR gene.

RESULTS

The frequency distribution of polymorphism at -29 position of FSHR gene is altered in women with primary and secondary amenorrhea as compared to controls. AA genotype at -29 position of FSHR gene seems to be associated with increased serum FSH levels in the study subjects. We have identified a novel homozygous mutation C(1723)T (Ala(575)Val) in one woman with primary amenorrhea.

CONCLUSIONS

Our findings suggest that increased serum FSH levels in subjects with primary amenorrhea correlated to FSHR genotype at position -29. We identified a novel homozygous mutation C(1723)T (Ala(575)Val) in a woman with primary amenorrhea.

Genetic polymorphisms of FSHR, CYP17, CYP1A1, CAPN10, INSR, SERPINE1 genes in adolescent girls with polycystic ovary syndrome

BACKGROUND

Polycystic ovary syndrome (PCOS), whose genetic basis is not completely well understood, is the most common endocrine disorder in women and it typically develops during adolescence. The aim of this study is to investigate the possible association between single nucleotide polymorphisms (SNPs) of FSHR, CYP17, CYP1A1, CAPN10, INSR, SERPINE1 genes and PCOS in adolescent girls.

METHODS

DNA samples from forty-four adolescent girls with PCOS and 50 healthy controls were analyzed by PCR-RFLP and direct DNA sequencing to determine the genotypic frequency of 17 different polymorphic loci on the FSHR (A307T, N680S), CYP17 (-34 T/C), CYP1A1 (T6235C), CAPN10 (44, 43, 19, 63), INSR (exon 17 C/T), SERPINE1 (4G/5G) genes. Genotyping of exon 12 (six polymorphisms) and intron 12 (one polymorphism) of INSR gene by direct DNA sequencing was performed for the first time in this study.

RESULTS

No significant differences were observed in the genotype and allele distributions of above mentioned polymorphisms between cases and control groups.

CONCLUSION

Our data does not support an association between SNPs of FSHR, CYP17, CYP1A1, CAPN10, INSR, SERPINE1 genes and susceptibility to PCOS or related traits in Turkish adolescent girls.

The haplotype of two FSHR polymorphisms in ovarian cancer--a potential role of ethnology in risk modification

OBJECTIVES

The precise role of gonadotropins in the carcinogenesis of epithelial ovarian cancer remains uncertain. Recently, the haplotype of two single nucleotide polymorphisms, Thr307Ala (rs6165) and Asn680Ser (rs6166), has been described as a risk factor for ovarian cancer in Chinese women. In this study we investigated the impact of this haplotype regarding the risk to develop ovarian cancer as well as possible effects upon the clinical course in a Caucasian patient sample.

SUBJECTS AND METHODS

Determination of genotypes in 115 patients with primary epithelial ovarian cancer and 115 age-matched controls was performed by Pyrosequencing for Thr307Ala and by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) technique for Asn680Ser.

RESULTS

Analysis of the genotypes revealed almost complete linkage disequilibrium of both SNPs. The distribution of genotypes was not statistically significant different between ovarian cancer patients and age-matched controls. Clinical parameters such as overall survival, CA12-5 elevation at primary diagnosis, age at diagnosis, FIGO stage, grading, and platinum resistance were not statistically significantly different regarding genotypes.

CONCLUSIONS

We could not confirm the FSHR Ala307-Ser680 haplotype as a risk factor for epithelial ovarian cancer in Caucasian women. Hence, the modification of tumor risk may be affected by the ethnology of the patient collective. We could not find any associations of clinical parameters or course of the disease with the different genotypes.

Single nucleotide polymorphism analysis of the follicle-stimulating hormone (FSH) receptor in Japanese with male infertility: identification of codon combination with heterozygous variations of the two discrete FSH receptor gene

AIMS

Dysfunction of the FSH receptor (FSHR) may be involved in some form of male infertility with azoospermia or oligozoospermia. We assessed the discrete codon combination with homo/heterozygous variation of the exon 10 in the FSHR gene.

METHODS

The genotype of codon 307 and codon 680 were analysed in 352 patients with idiopathic male infertility and 145 men with proven fertility.

RESULTS AND CONCLUSION

There was no significant difference in the distributions of each homozygous codon 307 or 680 between these two groups as reported in the literature. However, the population with heterozygous combinations Thr/Ala (codon 307) and Ser/ Asn (codon 680) comprised 26% (38/146) and 44.9% (157/343) in subjects with proven fertility and idiopathic infertile men, respectively. Moreover, the heterozygous genotype Thr/Ala-Ser/Asn was significantly increased in infertile patients compared with the controls. This finding showed that the combination of heterozygous FSHR can be responsible for male infertility.

A distribution of two SNPs in exon 10 of the FSHR gene among the women with a diminished ovarian reserve in Ukraine

PURPOSE

To evaluate the association between phenotype and follicle stimulating hormone receptor (FSHR) genotype in women with ovarian dysfunction and patients with "poor response" to gonadotropin stimulation of ovulation.

METHODS

FSHR gene SNPs were analyzed by PCR and RFLP. "Poor responders" (ovarian dysfunction) group and "good responders" group constituted the study group. Normo-ovulatory women who gave birth to naturally conceived children formed control groups: under 35 years of age (control I) and over 35 years of age (control II).

RESULTS

The frequency of Ala307-Ser680/Ala307-Ser680 genotype was significantly more prevalent in the ovarian dysfunction group (26%) compared to the control I (7.7%) (P < 0.001) and a "good responders" group (12.5%) (P < 0.05); and in a "poor responders" group (33.3%) compared to a "good responders" group (P < 0.05), control I (P < 0.001) and control II (17.5%) (P < 0.05).

CONCLUSIONS

Our data shows the prevalence of the Ala307-Ser680/ Ala307-Ser680 genotype in the both groups of patients. The finding should have impact on the delineation of stimulation protocols.

Functional genetic polymorphisms and female reproductive disorders: Part I: Polycystic ovary syndrome and ovarian response

BACKGROUND

The identification of polymorphisms associated with a disease can help to elucidate its pathogenesis, and this knowledge can be used to improve prognosis for women with a particular disorder, such as polycystic ovary syndrome (PCOS). Since an altered response to ovarian stimulation is also a characteristic of the disease, further knowledge about its aetiology could help in defining the parameters that determine the response of an individual to ovarian stimulation.

METHODS

PubMed and EMBASE databases were systematically searched for gene association studies published until the end of August 2007, using search criteria relevant to PCOS and ovarian response to stimulation. Data from additional papers identified through hand searches were also included; 139 publications were reviewed.

RESULTS

Several genes involved in ovarian function and metabolism are associated with increased susceptibility to PCOS, but none is strong enough to correlate alone with susceptibility to the disease, or response to therapy. A single-nucleotide polymorphism in exon 10 of the FSH receptor (FSHR) gene, FSHR p.N680S, was consistently identified as having a significant association with ovarian response to FSH.

CONCLUSIONS

No consistent association between gene polymorphism and PCOS could be identified. The FSHR gene may play a significant role in the success of ovarian stimulation, and can be used as a marker to predict differences in FSHR function and ovarian response to FSH. Genotyping the FSHR p.N680S polymorphism may provide a means of identifying a population of poor responders before in vitro fertilization procedures are initiated.

Polymorphism of the FSH receptor and ovarian response to FSH

Follicle-stimulating hormone (FSH) is a key factor in human reproduction. FSH activates its receptor (FSHR) located exclusively on Sertoli cells in the testis and granulosa cells in the ovary. Two common single nucleotide polymorphisms (SNP) within exon 10 of the human FSHR gene result in two almost equally common allelic variants exhibiting threonine (Thr) or alanine (Ala) at position 307 in the hinge region, respectively, asparagine (Asn) or serine (Ser) at codon 680 of the intracellular domain. Clinical studies have demonstrated that p.N680S polymorphism determines the ovarian response to FSH stimulation in patients undergoing IVF-treatment. Patients with the Ser(680) allele need more FSH during the stimulation phase to reach the serum estradiol levels of Asn(680) patients. A study investigating women with normal, mono-ovulatory menstrual cycles revealed that the Ser(680)/Ser(680) genotype leads to higher FSH serum levels and a prolonged cycle. To date, the molecular mechanism underlying the partial "resistance" of the Ser(680)-FSHR to FSH remains unclear. Future experiments should extend our current understanding of FSH action on follicular selection and dominance, thereby permitting novel, patient-tailored therapies for infertility and fertility preservation.

Mutation analysis of NANOS3 in 80 Chinese and 88 Caucasian women with premature ovarian failure

NANOS3 encodes an RNA-binding protein and has a conserved function in germ cell development. Our objective was to investigate whether mutations in NANOS3 were present in Chinese and Caucasian women with premature ovarian failure. A known synonymous single-nucleotide polymorphism (rs 2016163) in exon 1 was identified through sequencing 80 Chinese and 88 Caucasian women with premature ovarian failure. No additional single-nucleotide polymorphisms or mutations were found in exons encoding for NANOS3. Our findings suggest that mutations in NANOS3 exons are rare in both Chinese and Caucasian women with premature ovarian failure.

[Follicle-stimulating hormone receptor polymorphism and ovarian function]

The FSH receptor presents several polymorphisms. Two of them, located at codon 307 and 680, are the most frequent. Threonine can be substituted by alanine at position 307 and serine can be substituted by asparagine at position 680. The two most frequent allelic combinations are Thr(307) -Asn (680) (60%) and Ala(307) -Ser (680) (40%). As the allelic variants at codon 307 and 680 are almost invariably associated, most of the studies assessed only one codon (680) and classified the women as homozygous (Ser/Ser ou Asn/Asn) or heterozygous (Asn/Ser). Several studies aimed to correlate the follicle-stimulating hormone receptor polymorphism and ovarian function. Women homozygous for the Ser (680) variant have higher follicular FSH levels and longer follicular phase length, which suggest a lower sensitivity to FSH. The FSH receptor genotype would also influence the sensitivity to exogenous FSH: as regards ovarian stimulation, higher recombinant FSH doses are needed for Ser/Ser homozygous women. The analysis of polymorphism in women with premature ovarian failure did not show a link with any particular allelic variant. In women with polycystic ovaries, the distribution of the allelic variants greatly varies from one study to another.

Genomic variants in polycystic ovary syndrome

The polycystic ovary syndrome (PCOS) is a common disorder in premenopausal women, characterized by the presence, among other traits, of hyperandrogenism, insulin resistance, and hyperinsulinism. The familial aggregation of PCOS lead the interest to the molecular genetic basis of this syndrome, especially to the genes encoding proteins involved in androgen synthesis and the regulation of insulin synthesis and action. Considering the relationship between insulin resistance and chronic inflammation, and the clustering of inflammatory markers in PCOS patients, recent studies focused on the involvement of proinflammatory genotypes on the pathogenesis of PCOS. Mounting evidence suggest at present a complex model of inheritance for PCOS, in which predisposing and protecting genomic variants interact with environmental factors such as obesity and a sedentary lifestyle, finally leading to the classic phenotype of this syndrome. Moreover, the association of hyperandrogenism, insulin resistance and chronic inflammation raised the possibility of an increase risk of cardiovascular disease in women suffering from PCOS. In the present review we will summarize the most important findings published to date regarding the molecular genetic mechanisms underlying the association of PCOS with insulin resistance and chronic inflammation, and the possible interaction of these mechanisms with environmental factors.

Single nucleotide polymorphisms of follicle-stimulating hormone receptor are associated with ovarian cancer susceptibility

Epidemiological studies suggested that ovulation was associated with ovarian carcinogenesis. Follicle-stimulating hormone (FSH) played an important role in follicular development and was recently found to affect growth of ovarian epithelial cells. Single nucleotide polymorphisms (SNPs) Thr307Ala and Asn680Ser were two non-synonymous variations in the coding region of the FSH receptor (FSHR) gene. This hitherto first case-control study investigating the association between these two FSHR SNPs and the risk of ovarian cancer involved 202 histopathologically confirmed ovarian cancer patients and 266 age-matched cancer-free control subjects using restriction fragment length polymorphism assay and direct sequencing. Our results demonstrated that the 307Ala and 680Ser carriers were associated with significantly increased risk of developing serous and mucinous types of ovarian cancers (P < 0.0005, OR = 2.60, 95% CI = 1.56-4.34; and P < 0.0005, OR = 2.89, 95% CI = 1.73-4.84, adjusted for age, respectively) but not endometrioid and clear cell types. The two SNPs were found to be in modest linkage disequilibrium, D' = 0.804 and 0.701, r2 = 0.581 and 0.406 for the cancer and control groups, respectively. The major haplotype of 307Ala-680Ser was also associated with higher cancer risk (P = 0.033, OR = 1.39, 95% CI = 1.03-1.88), especially for the serous and mucinous carcinomas (P = 0.001, OR = 1.82, 95% CI = 1.27-2.60). Our results suggested that the two FSHR SNPs might affect the susceptibility of women to specific subtypes of ovarian cancer. Different types of ovarian cancer might adopt distinct carcinogenetic pathways. Such understanding may be important in selecting patients for ovulation induction therapy.

Pharmacogenetics in ovarian stimulation - current concepts and future options

Tailoring ovarian stimulation to the individual patient can be challenging because the ovarian response varies substantially between patients. Pharmacogenetics has emerged as a new area of research to improve the balance between desired and undesired actions of drugs, based upon the genetic predisposition of the individual patient. Clinical studies have demonstrated that the p.N680S polymorphism of the FSH-receptor gene determines the ovarian response to FSH stimulation in patients undergoing IVF. In homozygous Ser(680)/Ser(680) type women, the FSH receptor appears to be more resistant to FSH action even in normal menstrual cycles. Therefore, genotyping of patients scheduled for ovarian stimulation could be an attractive tool to individualize FSH dosing according to genetic differences in ovarian sensitivity. More clinical studies are warranted to investigate the usefulness of genotyping for the p.N680S polymorphism as a routine diagnostic test before ovarian stimulation.

Controversial role of inhibin α-subunit gene in the aetiology of premature ovarian failure

BACKGROUND

Premature ovarian failure (POF) is characterized by hypergonadotropic amenorrhoea before the age of 40. Inhibin alpha-subunit (INHalpha) gene is proposed as a candidate gene due to its role in negative feedback control of FSH.

METHODS

Polymorphism -16C>T of INHalpha gene was studied in 61 POF patients and 82 controls above 40 years old (C > 40). Substitution 769G>A was studied in 59 POF patients, 76 C > 40 and 73 controls below 40 years old (C < 40).

RESULTS

No significant difference in risk of POF development for -16T allele was found when comparing idiopathic POF (I-POF) with C > 40 (Odds ratio = 1.46; 95% confidence interval = 0.63-3.19). Implication of -16C>T polymorphism in serum inhibin levels was analysed in 46 controls, and no significant differences (P > 0.05) were found between CC and CT + TT genotype groups when comparing either mid-follicular phase Pro-alphaC and inhibin B values or mid-luteal phase Pro-alphaC and inhibin A values. Heterozygosity for substitution 769G>A was found in 1 of 59 POF woman, 2 of 76 C > 40 and 6 of 73 C < 40. Presence of this substitution in a relevant number of control subjects is herein described for the first time.

CONCLUSION

Our results indicate that -16C>T and 769G>A variants in INHalpha gene may not be associated to POF disease.

Genetic complexity of FSH receptor function

The interaction between follicle-stimulating hormone (FSH) and the FSH receptor (FSHR) is essential for normal oogenesis and spermatogenesis. Recently, single-nucleotide polymorphisms (SNPs) have been assigned to the FSHR gene. These give rise to different FSHR haplotypes that modify the action of FSH. In women, FSH sensitivities during the menstrual cycle and different cycle lengths are observed, depending on the FSHR haplotype. Thus, SNPs of the FSHR determine the ovarian response and should, therefore, be considered in controlled ovarian hyperstimulation during assisted-reproduction techniques in women with normal ovarian function. In men, the impact of the FSHR SNPs is unclear. The genetic complexity of FSHR should be considered when studying FSH action. These SNPs are one of the first examples in which genetic changes contribute to fine-tuning the endocrine regulation of reproduction. A rational pharmacogenetic approach that combines FSH dose according to the FSHR haplotype is envisaged.

An update of the pathophysiology of human gonadotrophin subunit and receptor gene mutations and polymorphisms

New information about mutations and polymorphisms in the genes for the gonadotrophins and their receptors has become available in the last few years. In this short review mutations and polymorphisms in gonadotrophins, their receptors and their pathophysiological effects and implications are discussed. An increasingly clear picture about the structure–function relationships of gonadotrophin action is emerging from the combining the types and the locations of the mutations with their phenotypic effects and the information about the crystal structure of these molecules.

The molecular-genetic basis of functional hyperandrogenism and the polycystic ovary syndrome

The genetic mechanisms underlying functional hyperandrogenism and the polycystic ovary syndrome (PCOS) remain largely unknown. Given the large number of genetic variants found in association with these disorders, the emerging picture is that of a complex multigenic trait in which environmental influences play an important role in the expression of the hyperandrogenic phenotype. Among others, genomic variants in genes related to the regulation of androgen biosynthesis and function, insulin resistance, and the metabolic syndrome, and proinflammatory genotypes may be involved in the genetic predisposition to functional hyperandrogenism and PCOS. The elucidation of the molecular genetic basis of these disorders has been burdened by the heterogeneity in the diagnostic criteria used to define PCOS, the limited sample size of the studies conducted to date, and the lack of precision in the identification of ethnic and environmental factors that trigger the development of hyperandrogenic disorders. Progress in this area requires adequately sized multicenter collaborative studies after standardization of the diagnostic criteria used to classify hyperandrogenic patients, in whom modifying environmental factors such as ethnicity, diet, and lifestyle are identified with precision. In addition to classic molecular genetic techniques such as linkage analysis in the form of a whole-genome scan and large case-control studies, promising genomic and proteomic approaches will be paramount to our understanding of the pathogenesis of functional hyperandrogenism and PCOS, allowing a more precise prevention, diagnosis, and treatment of these prevalent disorders.