FSHB promoter polymorphism within evolutionary conserved element is associated with serum FSH level in men

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.

A cryptozoospermic infertile male with Y chromosome AZFc microdeletion and low FSH levels due to a simultaneous polymorphism in the FSHB gene: a case report

Genetic causes account for 10-15% of male factor infertility, making the genetic investigation an essential and useful tool, mainly in azoospermic and severely oligozoospermic men. In these patients, the most frequent findings are chromosomal abnormalities and Y chromosome long arm microdeletions, which cause a primary severe spermatogenic impairment with classically increased levels of FSH. On the other hand, polymorphisms in the FSH receptor (FSHR) and FSH beta chain (FSHB) genes have been associated with different FSH plasma levels, due to variations in the receptor sensitivity (FSHR) or in the production of FSH from the pituitary gland (FSHB). Here, we describe an unusual patient with a combined genetic alteration (classic AZFc deletion of the Y chromosome and TT homozygosity for the -211G>T polymorphism in the FSHB gene (rs10835638)), presenting with cryptozoospermia, severe hypospermatogenesis, and normal LH and testosterone plasma concentrations, but low FSH levels. The patient partially benefitted from treatment with FSH (150 IU three times/week for 6 months) which allowed him to cryopreserve enough motile spermatozoa to be used for intracytoplasmic sperm injection. According to our knowledge, this is the first report of an infertile man with AZFc microdeletion with low FSH plasma concentrations related to homozygosity for the -211G>T polymorphism in the FSHB gene.

Spontaneous alterations in semen parameters are associated with age, accessory gland function and the FSHB c.-211G>T variant

BACKGROUND

There is a strong within-subject alteration of semen parameters in men with infertility. However, it remains unknown in which subgroup variations are likely to occur and which semen parameters are affected.

OBJECTIVE

To evaluate parameters associated with spontaneous alterations in semen analysis.

PATIENTS AND METHODS

We retrospectively selected 3456 men with infertility without known causes affecting spermatogenesis or sperm output for analysis of repeated ejaculate samples. Exclusion criteria comprised sperm concentration <1 million/mL, abnormal follicle-stimulating hormone or low testosterone, and low bitesticular volume (<10 mL). Grouped linear two-level nested mixed-effect models were applied. The analyzed parameters included abstinence time, bitesticular volume, age, accessory gland markers, follicle-stimulating hormone, and FSHB c.-211 variants.

RESULTS

Groups include A (n = 397): ≥1.0 to <5.0 million/mL, B (n = 708): ≥5.0 to <15.0 million/mL, and C (n = 2351): ≥15.0 million/mL. Groups A, B, and C: changes in ejaculate volume were associated with alterations in total sperm count and motility (p < 0.003). Changes were, controlled for abstinence time (p < 0.001), related to α-glucosidase, fructose, or zinc (p = 0.005-0.02). Group A + B: fluctuations in follicle-stimulating hormone level influenced sperm concentration/count (p = 0.004-0.02), albeit only in men with FSHB c.-211 GG (p = 0.007-0.02). T-allele carriers did not show changes in follicle-stimulating hormone levels (p > 0.1). Group B: age <50 years (p = 0.007-0.01) and normal bitesticular volume (p = 0.008-0.02) were associated with spontaneous increases in sperm concentration, count, and motility.

CONCLUSION

Semen parameters exhibit intra-individual alterations associated with organic, hormonal, and genetic variables. Changes are pronounced in younger men with normal bitesticular volume and oligozoospermia to almost normozoospermia. The effect is modulated by abstinence time, accessory gland function, and fluctuations in follicle-stimulating hormone level, which is bound to FSHB c.-211G>T variant. Judgment of semen analysis should be based on two semen samples, with abstinence times between 4 and 5 days. As a future perspective, it might be investigated whether younger men with normal bitesticular volume who are unable to elicit increases in serum follicle-stimulating hormone (FSHB c.-211 genotype of GT/TT) benefit from improving accessory gland function and increasing follicle-stimulating hormone.

Male infertility and gonadotropin treatment: What can we learn from real-world data?

Gonadotropin therapy to treat specific male infertility disorders associated with hypogonadotropic hypogonadism is evidence-based and effective in restoring spermatogenesis and fertility. In contrast, its use to improve fertility in men with idiopathic oligozoospermia or nonobstructive azoospermia remains controversial, despite being widely practiced. The existence of two major inter-related pathways for spermatogenesis, including FSH and intratesticular testosterone, provides a rationale for empiric hormone stimulation therapy in both eugonadal and hypogonadal males with idiopathic oligozoospermia or nonobstructive azoospermia. Real-world data (RWD) on gonadotropin stimulating for these patient subsets, mainly using human chorionic gonadotropin and follicle-stimulating hormone, accumulated gradually, showing a positive therapeutic effect in some patients, translated by increased sperm production, sperm quality, and sperm retrieval rates. Although more evidence is needed, current insights from RWD research indicate that selected male infertility patients might be managed more effectively using gonadotropin therapy, with potential gains for all parties involved.

Immune and spermatogenesis-related loci are involved in the development of extreme patterns of male infertility

We conducted a genome-wide association study in a large population of infertile men due to unexplained spermatogenic failure (SPGF). More than seven million genetic variants were analysed in 1,274 SPGF cases and 1,951 unaffected controls from two independent European cohorts. Two genomic regions were associated with the most severe histological pattern of SPGF, defined by Sertoli cell-only (SCO) phenotype, namely the MHC class II gene HLA-DRB1 (rs1136759, P = 1.32E-08, OR = 1.80) and an upstream locus of VRK1 (rs115054029, P = 4.24E-08, OR = 3.14), which encodes a protein kinase involved in the regulation of spermatogenesis. The SCO-associated rs1136759 allele (G) determines a serine in the position 13 of the HLA-DRβ1 molecule located in the antigen-binding pocket. Overall, our data support the notion of unexplained SPGF as a complex trait influenced by common variation in the genome, with the SCO phenotype likely representing an immune-mediated condition.

A GWAS in a large case-control cohort of European ancestry identifies two genomic regions, the MHC class II gene HLA-DRB1 and an upstream locus of VRK1, that are associated with the most severe phenotype of spermatogenic failure.

A GWAS in Idiopathic/Unexplained Infertile Men Detects a Genomic Region Determining Follicle-Stimulating Hormone Levels

CONTEXT

Approximately 70% of infertile men are diagnosed with idiopathic (abnormal semen parameters) or unexplained (normozoospermia) infertility, with the common feature of lacking etiologic factors. Follicle-stimulating hormone (FSH) is essential for initiation and maintenance of spermatogenesis. Certain single-nucleotide variations (SNVs; formerly single-nucleotide polymorphisms [SNPs]) (ie, FSHB c.-211G > T, FSHR c.2039A > G) are associated with FSH, testicular volume, and spermatogenesis. It is unknown to what extent other variants are associated with FSH levels and therewith resemble causative factors for infertility.

OBJECTIVE

We aimed to identify further genetic determinants modulating FSH levels in a cohort of men presenting with idiopathic or unexplained infertility.

METHODS

We retrospectively (2010-2018) selected 1900 men with idiopathic/unexplained infertility. In the discovery study (n = 760), a genome-wide association study (GWAS) was performed (Infinium PsychArrays) in association with FSH values (Illumina GenomeStudio, v2.0). Minor allele frequencies (MAFs) were analyzed for the discovery and an independent normozoospermic cohort. In the validation study (n = 1140), TaqMan SNV polymerase chain reaction was conducted for rs11031005 and rs10835638 in association with andrological parameters.

RESULTS

Imputation revealed 9 SNVs in high linkage disequilibrium, with genome-wide significance (P < 4.28e-07) at the FSHB locus 11p.14.1 being associated with FSH. The 9 SNVs accounted for up to a 4.65% variance in FSH level. In the oligozoospermic subgroup, this was increased up to 6.95% and the MAF was enhanced compared to an independent cohort of normozoospermic men. By validation, a significant association for rs11031005/rs10835638 with FSH (P = 4.71e-06/5.55e-07) and FSH/luteinizing hormone ratio (P = 2.08e-12/6.4e-12) was evident.

CONCLUSIONS

This GWAS delineates the polymorphic FSHB genomic region as the main determinant of FSH levels in men with unexplained or idiopathic infertility. Given the essential role of FSH, molecular detection of one of the identified SNVs that causes lowered FSH and therewith decreases spermatogenesis could resolve the idiopathic/unexplained origin by this etiologic factor.

A multi-level investigation of the genetic relationship between endometriosis and ovarian cancer histotypes

Endometriosis is associated with increased risk of epithelial ovarian cancers (EOCs). Using data from large endometriosis and EOC genome-wide association meta-analyses, we estimate the genetic correlation and evaluate the causal relationship between genetic liability to endometriosis and EOC histotypes, and identify shared susceptibility loci. We estimate a significant genetic correlation (r_g) between endometriosis and clear cell (r_g = 0.71), endometrioid (r_g = 0.48), and high-grade serous (r_g = 0.19) ovarian cancer, associations supported by Mendelian randomization analyses. Bivariate meta-analysis identified 28 loci associated with both endometriosis and EOC, including 19 with evidence for a shared underlying association signal. Differences in the shared risk suggest different underlying pathways may contribute to the relationship between endometriosis and the different histotypes. Functional annotation using transcriptomic and epigenomic profiles of relevant tissues/cells highlights several target genes. This comprehensive analysis reveals profound genetic overlap between endometriosis and EOC histotypes with valuable genomic targets for understanding the biological mechanisms linking the diseases.

•

Endometriosis is genetically correlated with CCOC, ENOC, and HGSOC

•

Genetic liability to endometriosis confers risk of these EOC histotypes

•

Profound colocalization of genetic associations at endometriosis and EOC risk loci

•

Functional annotation highlights shared target genes elucidating the genetic link

Multivariate, region-based genetic analyses of facets of reproductive aging in White and Black women

BACKGROUND

Age at final menstrual period (FMP) and the accompanying hormone trajectories across the menopause transition do not occur in isolation, but likely share molecular pathways. Understanding the genetics underlying the endocrinology of the menopause transition may be enhanced by jointly analyzing multiple interrelated traits.

METHODS

In a sample of 347 White and 164 Black women from the Study of Women's Health Across the Nation (SWAN), we investigated pleiotropic effects of 54 candidate genetic regions of interest (ROI) on 5 menopausal traits (age at FMP and premenopausal and postmenopausal levels of follicle stimulation hormone and estradiol) using multivariate kernel regression (Multi-SKAT). A backward elimination procedure was used to identify which subset of traits were most strongly associated with a specific ROI.

RESULTS

In White women, the 20 kb ROI around rs10734411 was significantly associated with the multivariate distribution of age at FMP, premenopausal estradiol, and postmenopausal estradiol (omnibus p-value = .00004). This association did not replicate in the smaller sample of Black women.

CONCLUSION

This study using a region-based, multiple-trait approach suggests a shared genetic basis among multiple facets of reproductive aging.

Genetic variants of gonadotrophins and their receptors: Impact on the diagnosis and management of the infertile patient

This narrative review is concerned with genetic variants of the genes encoding gonadotrophin subunits and their receptors, as well as their implications into the diagnosis and treatment of infertility. We first review briefly the basics of molecular biology and biochemistry of gonadotrophin and gonadotrophin receptor structure and function, then describe the phenotypic effects of polymorphisms and mutations of these genes, followed by diagnostic aspects. We will then summarise the information that inactivating gonadotrophin receptor mutations have provided about the controversial topic of extragonadal gonadotrophin action. Finally, we will close with the current and future therapeutic approaches on patients with gonadotrophin and their receptor mutations.

Translational aspects of novel findings in genetics of male infertility-status quo 2021

INTRODUCTION

Male factor infertility concerns 7-10% of men and among these 40-60% remain unexplained.

SOURCES OF DATA

This review is based on recent published literature regarding the genetic causes of male infertility.

AREAS OF AGREEMENT

Screening for karyotype abnormalities, biallelic pathogenic variants in the CFTR gene and Y-chromosomal microdeletions have been routine in andrology practice for >20 years, explaining ~10% of infertility cases. Rare specific conditions, such as congenital hypogonadotropic hypogonadism, disorders of sex development and defects of sperm morphology and motility, are caused by pathogenic variants in recurrently affected genes, which facilitate high diagnostic yield (40-60%) of targeted gene panel-based testing.

AREAS OF CONTROVERSY

Progress in mapping monogenic causes of quantitative spermatogenic failure, the major form of male infertility, has been slower. No 'recurrently' mutated key gene has been identified and worldwide, a few hundred patients in total have been assigned a possible monogenic cause.

GROWING POINTS

Given the high genetic heterogeneity, an optimal approach to screen for heterogenous genetic causes of spermatogenic failure is sequencing exomes or in perspective, genomes. Clinical guidelines developed by multidisciplinary experts are needed for smooth integration of expanded molecular diagnostics in the routine management of infertile men.

AREAS TIMELY FOR DEVELOPING RESEARCH

Di-/oligogenic causes, structural and common variants implicated in multifactorial inheritance may explain the 'hidden' genetic factors. It is also critical to understand how the recently identified diverse genetic factors of infertility link to general male health concerns across lifespan and how the clinical assessment could benefit from this knowledge.

Reduced FSH and LH action: implications for medically assisted reproduction

Luteinizing hormone (LH) and follicle-stimulating hormone (FSH) play complementary roles in follicle development and ovulation via a complex interaction in the hypothalamus, anterior pituitary gland, reproductive organs, and oocytes. Impairment of the production or action of gonadotropins causes relative or absolute LH and FSH deficiency that compromises gametogenesis and gonadal steroid production, thereby reducing fertility. In women, LH and FSH deficiency is a spectrum of conditions with different functional or organic causes that are characterized by low or normal gonadotropin levels and low oestradiol levels. While the causes and effects of reduced LH and FSH production are very well known, the notion of reduced action has received less attention by researchers. Recent evidence shows that molecular characteristics, signalling as well as ageing, and some polymorphisms negatively affect gonadotropin action. These findings have important clinical implications, in particular for medically assisted reproduction in which diminished action determined by the afore-mentioned factors, combined with reduced endogenous gonadotropin production caused by GnRH analogue protocols, may lead to resistance to gonadotropins and, thus, to an unexpected hypo-response to ovarian stimulation. Indeed, the importance of LH and FSH action has been highlighted by the International Committee for Monitoring Assisted Reproduction Technologies (ICMART) in their definition of hypogonadotropic hypogonadism as gonadal failure associated with reduced gametogenesis and gonadal steroid production due to reduced gonadotropin production or action. The aim of this review is to provide an overview of determinants of reduced FSH and LH action that are associated with a reduced response to ovarian stimulation.

Genetic variants predictive of reproductive aging are associated with vasomotor symptoms in a multiracial/ethnic cohort

OBJECTIVE

Vasomotor symptoms (VMS), hot flashes, and night sweats are cardinal symptoms of the menopausal transition. Little is known about genetic influences on VMS. This study evaluated whether previously identified genetic factors predictive of VMS, age at menarche, and age at menopause were associated with VMS in a multiracial/ethnic cohort.

METHODS

For 702 White, 306 Black, 126 Chinese, and 129 Japanese women from the Study of Women's Health Across the Nation (SWAN) Genomic Substudy, we created polygenic risk scores (PRSs) from genome-wide association studies of VMS and ages at menarche and menopause. PRSs and single nucleotide polymorphisms (SNPs) from a previously identified VMS locus (tachykinin receptor 3 [TACR3]) were evaluated for associations with frequent VMS (VMS ≥6 days in the past 2 weeks at any visit) and with VMS trajectories (persistently low, early onset, final menstrual period onset, persistently high).

RESULTS

The C-allele of rs74827081 in TACR3 was associated with reduced likelihood of frequent VMS in White women (odds ratio [OR] = 0.49 [95% CI, 0.29-0.83]). With higher menarche PRS (later menarche), Black women were less likely (OR = 0.55 [95% CI, 0.38-0.78]) to report frequent VMS. With higher PRS for age at menarche, Black women were also less likely to have a persistently high VMS trajectory (OR = 0.55 [95% CI, 0.34-0.91]), whereas White women (OR = 0.75 [95% CI, 0.58-0.98]) were less likely to have a final menstrual period onset trajectory (vs persistently low). Chinese women with higher menopause PRS were more likely to have frequent VMS (OR = 2.29 [95% CI, 1.39-3.78]). Associations were substantively similar after excluding rs74827081 C-allele carriers.

CONCLUSIONS

Genetic factors predictive of reproductive aging are also associated with VMS, suggesting that VMS have a polygenic architecture. Further study in this area may help to identify new targets for novel VMS therapies.

Associations between polygenic risk score for age at menarche and menopause, reproductive timing, and serum hormone levels in multiple race/ethnic groups

OBJECTIVE

We assessed associations of genetic loci that contribute to age at menarche and menopause with sentinel menopausal traits in multiple race/ethnic groups.

METHODS

Genetic data from the Study of Women's Health Across the Nation include 738 White, 366 Black, 139 Chinese, and 145 Japanese women aged 42 to 52 at baseline. We constructed standardized polygenic risk scores (PRSs) using single nucleotide polymorphisms identified from large-scale genome-wide association studies meta-analyses of ages at menopause and menarche, evaluating associations with each trait within each race/ethnic group.

RESULTS

Menopause PRS was significantly associated with age at menopause in White women after Bonferroni correction (P < 0.004) and nominally associated in Chinese and Japanese women (P < 0.05) (7.4-8.5 mo delay for one standard deviation [SD] increase in PRS). Menarche PRS was significantly associated with age at menarche in White (P < 0.004) and nominally associated in Black and Japanese women (P < 0.05) (2.6-4.8 mo delay for one SD increase). In White women, menarche and menopause PRSs were significantly associated (P < 0.004) with shorter and longer (5.9 and 9.6 mo for one SD increase) reproductive lifespans, respectively, and menopause PRS with a longer menopausal transition (7.1 mo for one SD increase). We observed a significant positive association (P < 0.004) between menopause PRS and E2 level 2 years before menopause and a nominal association (P < 0.05) 2 years after menopause in Japanese women.

CONCLUSIONS

In addition to menopausal timing, PRSs associated with onset and ending of reproductive life were associated with reproductive lifespan, length of the menopausal transition, and E2 levels in different race/ethnic groups.

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.

Advances in the Regulation of Mammalian Follicle-Stimulating Hormone Secretion

Simple Summary

The reproduction of mammals is regulated by the hypothalamic-pituitary-gonadal axis. Follicle stimulating hormone, as one of the gonadotropins secreted by the pituitary gland, plays an immeasurable role. This article mainly reviews the molecular basis and classical signaling pathways that regulate the synthesis and secretion of follicle stimulating hormone, and summarizes its internal molecular mechanism, which provides a certain theoretical basis for the research of mammalian reproduction regulation and the application of follicle stimulating hormone in production practice.

Abstract

Mammalian reproduction is mainly driven and regulated by the hypothalamic-pituitary-gonadal (HPG) axis. Follicle-stimulating hormone (FSH), which is synthesized and secreted by the anterior pituitary gland, is a key regulator that ultimately affects animal fertility. As a dimeric glycoprotein hormone, the biological specificity of FSH is mainly determined by the β subunit. As research techniques are being continuously innovated, studies are exploring the underlying molecular mechanism regulating the secretion of mammalian FSH. This article will review the current knowledge on the molecular mechanisms and signaling pathways systematically regulating FSH synthesis and will present the latest hypothesis about the nuclear cross-talk among the various endocrine-induced pathways for transcriptional regulation of the FSH β subunit. This article will provide novel ideas and potential targets for the improved use of FSH in livestock breeding and therapeutic development.

A common 1.6 mb Y-chromosomal inversion predisposes to subsequent deletions and severe spermatogenic failure in humans

Male infertility is a prevalent condition, affecting 5–10% of men. So far, few genetic factors have been described as contributors to spermatogenic failure. Here, we report the first re-sequencing study of the Y-chromosomal Azoospermia Factor c (AZFc) region, combined with gene dosage analysis of the multicopy DAZ, BPY2, and CDYgenes and Y-haplogroup determination. In analysing 2324 Estonian men, we uncovered a novel structural variant as a high-penetrance risk factor for male infertility. The Y lineage R1a1-M458, reported at >20% frequency in several European populations, carries a fixed ~1.6 Mb r2/r3 inversion, destabilizing the AZFc region and predisposing to large recurrent microdeletions. Such complex rearrangements were significantly enriched among severe oligozoospermia cases. The carrier vs non-carrier risk for spermatogenic failure was increased 8.6-fold (p=6.0×10⁻⁴). This finding contributes to improved molecular diagnostics and clinical management of infertility. Carrier identification at young age will facilitate timely counselling and reproductive decision-making.

Genetic Regulation of Physiological Reproductive Lifespan and Female Fertility

There is substantial genetic variation for common traits associated with reproductive lifespan and for common diseases influencing female fertility. Progress in high-throughput sequencing and genome-wide association studies (GWAS) have transformed our understanding of common genetic risk factors for complex traits and diseases influencing reproductive lifespan and fertility. The data emerging from GWAS demonstrate the utility of genetics to explain epidemiological observations, revealing shared biological pathways linking puberty timing, fertility, reproductive ageing and health outcomes. The observations also identify unique genetic risk factors specific to different reproductive diseases impacting on female fertility. Sequencing in patients with primary ovarian insufficiency (POI) have identified mutations in a large number of genes while GWAS have revealed shared genetic risk factors for POI and ovarian ageing. Studies on age at menopause implicate DNA damage/repair genes with implications for follicle health and ageing. In addition to the discovery of individual genes and pathways, the increasingly powerful studies on common genetic risk factors help interpret the underlying relationships and direction of causation in the regulation of reproductive lifespan, fertility and related traits.

FSHB Transcription is Regulated by a Novel 5' Distal Enhancer With a Fertility-Associated Single Nucleotide Polymorphism

The pituitary gonadotropins, follicle-stimulating hormone (FSH) and luteinizing hormone, signal the gonads to regulate male and female fertility. FSH is critical for female fertility as it regulates oocyte maturation, ovulation, and hormone synthesis. Multiple genome-wide association studies (GWAS) link a 130 Kb locus at 11p14.1, which encompasses the FSH beta-subunit (FSHB) gene, with fertility-related traits that include polycystic ovary syndrome, age of natural menopause, and dizygotic twinning. The most statistically significant single nucleotide polymorphism from several GWAS studies (rs11031006) resides within a highly conserved 450 bp region 26 Kb upstream of the human FSHB gene. Given that sequence conservation suggests an important biological function, we hypothesized that the region could regulate FSHB transcription. In luciferase assays, the conserved region enhanced FSHB transcription and gel shifts identified a binding site for Steroidogenic factor 1 (SF1) contributing to its function. Analysis of mouse pituitary single-cell ATAC-seq demonstrated open chromatin at the conserved region exclusive to a gonadotrope cell-type cluster. Additionally, enhancer-associated histone markers were identified by immunoprecipitation of chromatin from mouse whole pituitary and an immortalized mouse gonadotrope-derived LβT2 cell line at the conserved region. Furthermore, we found that the rs11031006 minor allele upregulated FSHB transcription via increased SF1 binding to the enhancer. All together, these results identify a novel upstream regulator of FSHB transcription and indicate that rs11031006 can modulate FSH levels.

FSHB and FSHR gene variants exert mild modulatory effect on reproductive hormone levels and testis size but not on semen quality: A study of 2020 men from the general Danish population

BACKGROUND

Spermatogenesis depends on stimulation by follicle-stimulating hormone (FSH) which binds to FSH receptors (FSHR) on testicular Sertoli cells. Three FSH-related single-nucleotide polymorphisms (SNPs), FSHB -211G>T (rs10835638), FSHR -29G>A (rs1394205) and FSHR 2039A>G (rs6166) affect FSH action, and have been suggested to affect testicular function, but the evidence is uncertain.

OBJECTIVE

To describe the associations between the three SNPs and testicular function in a large and well-characterised cohort of men from the general population.

MATERIALS AND METHODS

A cross-sectional study of 2020 Danish men unselected regarding testicular function. Outcome variables were semen parameters, reproductive hormones and testis size. Genotyping was done by competitive allele-specific quantitative PCR. Differences in genotype frequencies were tested by chi-square test and associations between genotypes and outcomes were assessed by multivariate linear regressions.

RESULTS

The SNPs affected serum FSH; carriers of the variant affecting FSH secretion (FSHB -211G>T) had lower FSH levels while carriers of variants affecting receptor expression (FSHR -29G>A) and receptor sensitivity (FSHR 2039A>G) had higher FSH levels. Carriers of FSHB -211G>T had lower calculated free testosterone/LH ratio. Although both FSHB -211G>T and FSHR 2039A>G were associated with smaller testis size, no clear association was detected in relation to any semen parameters, except a lower total number of morphologically normal spermatozoa in the heterozygous carriers of the FSHB -211G>T DISCUSSION AND CONCLUSION: The studied polymorphisms have only minor modulating influence on testis size and function in healthy men. We detected subtle effects of the three SNPs on FSH levels, but also effects of FSHB -211G>T on calculated free testosterone/LH ratio, compatible with altered Leydig cell function. Thus, the role of these FSH-related polymorphisms is complex and modest in men with normal testicular function, but the possible importance of FSH polymorphisms in men with impaired testicular function should be evaluated in future studies in more detail.

The Relationship Between Serum Delta FSH Level and Ovarian Response in IVF/ICSI Cycles

Background

When ovarian response to FSH stimulation for IVF/ICSI is unsatisfactory, the FSH dose is often adjusted in the treatment cycles, thereby assuming that hormone status and follicular development were insufficient for optimal stimulation.

Objectives

To evaluate whether serum delta FSH levels between D6 of gonadotrophin use and basal serum FSH or between D6 of gonadotrophin use and D1 of gonadotrophin use predict ovarian response in IVF/ICSI cycles.

Method

The participants of this retrospective study were chosen from the Reproductive Medicine, The First Affiliated Hospital of Zhengzhou University between August 2015 and December 2017 (n = 3,109), and during the COS, each participant was given a fixed dose of rFSH in the first 6 days. Delta FSH1: The difference of serum FSH between D6 of gonadotrophin use and basal serum FSH. Delta FSH2: The difference of serum FSH between D6 of gonadotrophin use and D1 of gonadotrophin use. Logistic regression was used to analyze the association between delta FSH1 level and delta FSH2 level and ovarian response. Besides, we also use the tertile statistics to divide the groups.

Results

Part I: Delta FSH1 levels (mean: 1.41 ± 3.46) in normal responders were higher than delta FSH1 levels (mean: 1.07 ± 23.89) in hyper responders (P = 0.0248). The tertile of delta FSH1 is dif ≤ 0, 0 < dif ≤ 2.25 and dif > 2.25. Compared with the hyper responder, the delta FSH1 (0 < dif ≤ 2.25 and dif > 2.25) in the normal responder has a higher ratio and is statistically significant. Part II: Delta FSH2 levels (mean: 4.90 ± 2.84) in normal responders were similar with delta FSH2 levels (mean: 4.74 ± 2.09) in hyper responders (P = 0.103). The tertile of delta FSH1 is dif ≤ 3.91, 3.91 < dif ≤ 5.69 and dif > 5.69. Compared with the hyper responders, the delta FSH2 (3.91 < dif ≤ 5.69 and dif > 5.69) in the normal responders has a higher ratio and is statistically significant.

Conclusions

There is a weak relationship between ovarian response and serum delta FSH levels.

Association Between Levels of Sex Hormones and Risk of Esophageal Adenocarcinoma and Barrett's Esophagus

BACKGROUND & AIMS

Esophageal adenocarcinoma (EAC) occurs most frequently in men. We performed a Mendelian randomization analysis to investigate whether genetic factors that regulate levels of sex hormones are associated with risk of EAC or Barrett's esophagus (BE).

METHODS

We conducted a Mendelian randomization analysis using data from patients with EAC (n = 2488) or BE (n = 3247) and control participants (n = 2127), included in international consortia of genome-wide association studies in Australia, Europe, and North America. Genetic risk scores or single-nucleotide variants were used as instrumental variables for 9 specific sex hormones. Logistic regression provided odds ratios (ORs) with 95% CIs.

RESULTS

Higher genetically predicted levels of follicle-stimulating hormones were associated with increased risks of EAC and/or BE in men (OR, 1.14 per allele increase; 95% CI, 1.01-1.27) and in women (OR, 1.28; 95% CI, 1.03-1.59). Higher predicted levels of luteinizing hormone were associated with a decreased risk of EAC in men (OR, 0.92 per SD increase; 95% CI, 0.87-0.99) and in women (OR, 0.93; 95% CI, 0.79-1.09), and decreased risks of BE (OR, 0.88; 95% CI, 0.77-0.99) and EAC and/or BE (OR, 0.89; 95% CI, 0.79-1.00) in women. We found no clear associations for other hormones studied, including sex hormone-binding globulin, dehydroepiandrosterone sulfate, testosterone, dihydrotestosterone, estradiol, progesterone, or free androgen index.

CONCLUSIONS

In a Mendelian randomization analysis of data from patients with EAC or BE, we found an association between genetically predicted levels of follicle-stimulating and luteinizing hormones and risk of BE and EAC.

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.

Optimal Endocrine Evaluation and Treatment of Male Infertility

This article aims to define the optimal endocrine workup of male factor infertility, including evaluation and treatment of men who have previously been on exogenous testosterone or anabolic steroids. Future directions include the expansion of genetic testing for infertility to include endocrine gene products.

FSH RECEPTOR AND FSH BETA CHAIN POLYMORPHISM INVOLVEMENT IN INFERTILITY AND ENDOMETRIOSIS DISEASE

OBJECTIVES

The purpose of this study was to evaluate the association between the follicle-stimulating hormone (FSH) receptor (c.-29G>A) and FSH beta chain (c.-280G>T) polymorphisms and endometriosis in Romanian women.

MATERIAL AND METHODS

We performed the polymorphic analysis of the FSH receptor gene and FSH beta chain in 44 patients with endometriosis and 34 controls. Genomic DNA was obtained from peripheral blood and polymorphisms were investigated using restriction fragment length polymorphism analysis (RFLP).

RESULTS

There were no significant differences in genotype frequencies of FSH receptor gene between endometriosis patients and controls. For the heterozygous type of the FSH receptor polymorphism (c.-29G>A) we did not find a significant difference in its frequency between patients with minimal/mild and moderate/severe endometriosis (p = 0.136). Also, the FSH beta chain (c.-280G> T) polymorphism frequency was not significantly associated with the severity of endometriosis (p = 0.966).

CONCLUSIONS

FSH receptor and FSH beta chain polymorphisms do not seem to influence the severity of endometriosis, but they could be correlated with female infertility (primary or secondary), therefore further studies are required to debate this topic.

A genome-wide association study identifies FSHR rs2300441 associated with follicle-stimulating hormone levels

Follicle-stimulating hormone (FSH) and luteinizing hormone (LH) play critical roles in female reproduction, while the underlying genetic basis is poorly understood. Genome-wide association studies (GWASs) of FSH and LH levels were conducted in 2590 Chinese females including 1882 polycystic ovary syndrome (PCOS) cases and 708 controls. GWAS for FSH level identified multiple variants at FSHR showing genome-wide significance with the top variant (rs2300441) located in the intron of FSHR. The A allele of rs2300441 led to a reduced level of FSH in the PCOS group (β = -.43, P = 6.70 × 10^-14 ) as well as in the control group (β = -.35, P = 6.52 × 10^-4 ). In the combined sample, this association was enhanced after adjusting for the PCOS status (before: β = -.38, P = 1.77 × 10^-13 ; after: β = -.42, P = 3.33 × 10^-16 ), suggesting the genetic effect is independent of the PCOS status. The rs2300441 explained sevenfold higher proportion of the FSH variance than the total variance explained by the two previously reported FSHR missense variants (rs2300441 R² = 1.40% vs rs6166 R² = 0.17%, rs6165 R² = 0.03%). GWAS for LH did not identify any genome-wide significant associations. In conclusion, we identified genome-wide significant association between variants in FSHR and circulating FSH first, with the top associated variant rs2300441 might be a primary contributor at the population level.

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.

Does the FSHB c.-211G>T polymorphism impact Sertoli cell number and the spermatogenic potential in infertile patients?

BACKGROUND

A genetic variant within the FSHB gene can deviate FSH action on spermatogenesis. The c.-211G>T FSHB single nucleotide polymorphism impacts FSHB transcription and biosynthesis due to interference with the LHX3 transcription factor binding. This SNP was previously shown to be strongly associated with lowered testicular volume, reduced sperm counts, and decreased FSH levels in patients carrying one or two T-alleles.

OBJECTIVE

To determine the impact of the SNP FSHB c.-211G>T on Sertoli cell (SC) number, Sertoli cell workload (SCWL) and thereby spermatogenic potential.

MATERIAL AND METHODS

Testicular biopsies of 31 azoospermic, homozygous T patients (26 non-obstructive azoospermia (NOA), and five obstructive azoospermia (OA)) were matched to patients with GG genotype. Marker proteins for SC (SOX9), spermatogonia (MAGE A4), and round spermatids (CREM) were used for semi-automatical quantification by immunofluorescence. SCWL (number of germ cells served by one SC) was determined and an unbiased clustering on the patient groups performed.

RESULTS

Quantification of SC number in NOA patients did not yield significant differences when stratified by FSHB genotype. SC numbers are also not significantly different between FSHB genotypes for the OA patient group and between NOA and OA groups. SCWL in the NOA patient cohort is significantly reduced when compared to the OA control patients; however, in neither group an effect of the genotype could be observed. The cluster analysis of the whole study cohort yielded two groups only, namely NOA and OA, and no clustering according to the FSHB genotype.

DISCUSSION AND CONCLUSION

The FSHB c.-211G>T polymorphism does not affect SC numbers or SCWL, thereby in principle maintaining the spermatogenic potential. The previously observed clinical phenotype for the FSHB genotype might therefore be caused by a hypo-stimulated spermatogenesis and not due to a decreased SC number.

Prediction model for testis histology in men with non-obstructive azoospermia: evidence for a limited predictive role of serum follicle-stimulating hormone

PURPOSE

The present prediction model was intended to verify whether serum FSH level could be predictive of testis histology in patients with non-obstructive azoospermia (NOA).

METHODS

We evaluated two datasets of patients with NOA: the first (San Paolo dataset) comprising 558 patients, 18-63 years old, the second (Procrea dataset) composed by 143 patients, 26-62 years old; bot datasets were combined to obtain a validation set. Multinomial logistic regression was first run with serum FSH and testis volume as independent predictors of testis histology, then, the correctly classified histological subcategories were set as outcome variables of a prediction model in both development and validation sets.

RESULTS

Multinomial logistic regression showed that FSH was a significant predictor of testis histology in 58% of cases, although it was unable to correctly classify cases with focal SCO or maturation arrest (MA). A prediction model was then run with hypospermatogenesis (HYPO) and Sertoli-only syndrome (SCO) as outcome variables of a binary logistic regression. FSH significantly predicted both HYPO and SCO, with a sensitivity of 40.9 and 80.7 and a specificity of 84.3 and 46.8 respectively. The model showed a fair discriminative ability (ROC AUC 0.705 and 0.709 respectively) and was adequately calibrated.

CONCLUSIONS

Supported by a robust statistical analysis, we conclude that serum FSH level cannot be considered a prognostic marker of spermatogenic dysfunction in patients with NOA.

FSHB -211 G>T Polymorphism as Predictor for TESE Success in Patients With Unexplained Azoospermia

CONTEXT

Testicular sperm extraction (TESE) followed by assisted reproductive techniques often remains the only therapeutic option for men with azoospermia due to spermatogenic failure. Reproductive parameters, such as gonadotropin levels and testicular volume or histopathology, contribute to the prediction of sperm retrieval rate (SRR) in TESE. However, there is an eminent lack of noninvasive predictive factors for TESE outcome.

OBJECTIVE

To clarify the impact of three common genetic variants affecting FSH and its cognate receptor on testicular histopathology patterns and SRR in TESE.

DESIGN

We evaluated the association of the single-nucleotide polymorphisms (SNP) FSHB -211G>T (rs10835638), FSHR -29G>A (rs1394205), and FSHR c.2039A>G (rs6166) with testicular histopathology and SRR in patients with azoospermia.

SETTING

Tertiary referral center for andrology.

PATIENTS OR OTHER PARTICIPANTS

Men (n = 1075) with azoospermia who underwent TESE (grouped by clinical pathologies).

INTERVENTION(S)

All participants underwent TESE.

MAIN OUTCOME MEASURE(S)

Testicular histopathology, SRR, and reproductive hormone levels.

RESULTS

FSHB -211G>T was significantly associated with reduced chances of sperm retrieval in patients with unexplained azoospermia. Indicating an additional mechanism, the association of the SNP with SSR could not be solely attributed to decreased FSH levels.

CONCLUSION

A common genetic factor was significantly associated with SRR in TESE. In perspective, a calculator or score including the noninvasive parameters FSH level, testicular volume, and FSHB haplotype should be considered to estimate the chances for sperm retrieval in men with azoospermia.

Genome-wide association study of anti-Müllerian hormone levels in pre-menopausal women of late reproductive age and relationship with genetic determinants of reproductive lifespan

Anti-Müllerian hormone (AMH) is required for sexual differentiation in the fetus, and in adult females AMH is produced by growing ovarian follicles. Consequently, AMH levels are correlated with ovarian reserve, declining towards menopause when the oocyte pool is exhausted. A previous genome-wide association study identified three genetic variants in and around the AMH gene that explained 25% of variation in AMH levels in adolescent males but did not identify any genetic associations reaching genome-wide significance in adolescent females. To explore the role of genetic variation in determining AMH levels in women of late reproductive age, we carried out a genome-wide meta-analysis in 3344 pre-menopausal women from five cohorts (median age 44-48 years at blood draw). A single genetic variant, rs16991615, previously associated with age at menopause, reached genome-wide significance at P = 3.48 × 10-10, with a per allele difference in age-adjusted inverse normal AMH of 0.26 standard deviations (SD) (95% confidence interval (CI) [0.18,0.34]). We investigated whether genetic determinants of female reproductive lifespan were more generally associated with pre-menopausal AMH levels. Genetically-predicted age at menarche had no robust association but genetically-predicted age at menopause was associated with lower AMH levels by 0.18 SD (95% CI [0.14,0.21]) in age-adjusted inverse normal AMH per one-year earlier age at menopause. Our findings provide genetic support for the well-established use of AMH as a marker of ovarian reserve.

FSHB -211 G>T is a major genetic modulator of reproductive physiology and health in childbearing age women

STUDY QUESTION

Are the genetic variants FSHB -211 G>T (rs10835638), FSHR c.2039 A>G (Asn680Ser, rs6166) and FSHR -29 G>A (rs1394205) associated with serum FSH, LH and anti-Müllerian hormone (AMH) levels in reproductive age women, their menstrual cycle parameters and risk of infertility?

SUMMARY ANSWER

Only the FSHB -211 G>T variant was a major genetic determinant of serum gonadotropin levels in both, eumenorrheic healthy women and female infertility patients, and the T-allele carrier status was enriched among idiopathic infertility cases.

WHAT IS KNOWN ALREADY

There are accumulating data on common genetic variants modulating reproductive parameters and fertility potential. FSHB -211 G>T represents the strongest acknowledged genetic factor contributing to male circulating gonadotropins levels. Respective data in women are limited and the two previously published studies have reached conflicting results. In addition, previous studies have consistently associated FSHR c.2039 A>G (but not FSHR -29 G>A) with female serum FSH level.

STUDY DESIGN, SIZE, DURATION

The study aimed to test robust and clinically meaningful genetic effects (if present) of the FSHB -211 G>T, FSHR c.2039 A>G and FSHR -29 G>A variants on female basal FSH, LH and AMH levels, and linked reproductive parameters. Genetic association testing was performed in two independent and clinically different study groups (i) eumenorrheic healthy women without known fertility problems (n = 169; 27.6 ± 6.1 years) and (ii) female partners of infertile couples (n = 186; 32.4 ± 4.7 years). The study groups were compared for allelic and genotypic distributions of the analysed variants.

PARTICIPANTS/MATERIALS, SETTING, METHODS

All participants were recruited during the HAPPY PREGNANCY study (2013-2015) at the Women's Clinic, Tartu University Hospital, Estonia. Serum FSH, LH and AMH were measured in the follicular phase (Days 2-6) of the menstrual cycle. All three single nucleotide polymorphisms (SNPs) were genotyped by PCR and Taqman allelic discrimination assay. The effect of the analysed variants on hormonal measurements and menstrual cycle data was assessed using linear regression under additive and recessive models adjusted by age, BMI and smoking status. Results of the two subgroups were combined in a meta-analysis applying the fixed effects model. Restricted maximum likelihood analysis was applied to estimate the proportion of total phenotypic variance of analysed reproductive parameters, explainable by the tested genetic variants. In case-control analysis, genetic association with infertility status was tested using Fisher's exact test and logistic regression adjusted by age, BMI and smoking status.

MAIN RESULTS AND THE ROLE OF CHANCE

In both study groups, T-allele of the FSHB -211 G>T was associated with significantly higher serum levels of FSH and LH. Results of the meta-analysis (additive genetic model) remained significant after Bonferroni correction for multiple testing: FSH, T-allele effect 0.80 IU/L, P = 1.2 × 10-3; LH, 1.58 IU/L, P = 1.8×10-8. A more pronounced effect of T-allele of the FSHB -211 G>T on circulating LH was identified as a driving factor to increased LH/FSH ratio (meta-analysis, P = 4.7 × 10-3). In healthy women, the FSHB -211 G>T variant was estimated to explain 3.5 and 7.1% of the total variance of the measured serum FSH and LH levels, respectively. The corresponding numbers for the infertility patients were 1.6 and 10.5%. Women with idiopathic infertility compared to controls exhibited a doubled T-allele frequency (23.6 versus 12.4%; P = 8.9 × 10-3) and a >3-fold excess of TT homozygotes (5.6 versus 1.8%; P = 3.5 × 10-2). The only association of the FSHR c.2039 A>G was detected with serum FSH levels in eumenorrheic healthy women, explaining 3.9% of the total parameter variance (G-allele effect 0.56 IU/L, P = 4.6 × 10-3). In the study group of healthy reproductive age women, the highest serum FSH levels were detected among the FSHB -211 T-allele carriers with the FSHR c.2039 GG-genotype (median 7.7 IU/L). In contrast, the lowest hormone concentrations were measured for the women carrying the combination of the FSHB -211 GG- and the FSHR c.2039 AA-homozygosity (median 5.8 IU/L, P = 9.6 × 10-3). None of the analysed reproductive parameters was associated with the FSHR -29 G>A variant. In our study groups, the tested polymorphisms did not reach significant associations with serum AMH measurements, menstrual cycle length or age at menarche.

LIMITATIONS, REASONS FOR CAUTION

Small sample size and the design involving two clinical groups with different reproductive histories may have limited the capacity to replicate the associations with the age at menarche and length of menstrual cycle, initially reported in large genome-wide association studies. Small sample size may have also affected the accuracy in estimating the contribution of the tested variants to the total phenotypic variance of measured gonadotropin concentrations. The group of eumenorrheic healthy women had its limitations as a control to estimate the true effect of analysed genetic variants on individual's fertility potential as the recruitment strategy had been targeted mostly towards younger women, who may not yet have planned to conceive a child by this age.

WIDER IMPLICATIONS OF THE FINDINGS

We propose that like in men, also in women the FSHB -211 G>T represents a key genetic modulator of circulating gonadotropin, leading to various possible downstream effects on reproductive physiology. This claim is strongly supported by the reports of genome-wide association studies on various female reproductive traits and diseases. In perspective, FSHB -211 G>T may have a diagnostic value in fertility clinics to detect female patients with genetically inherited elevated basal FSH and LH levels.

STUDY FUNDING/COMPETING INTEREST(S)

The study was supported by Estonian Science Foundation Grant (ETF9030 for M.L.); Institutional Research Grant (IUT34-12 for M.L.) and European Union through the European Regional Development Fund (project HAPPY PREGNANCY, 3.2.0701.12-0047; for M.L. and K.R.). The funders had no role in study design, data collection and analysis, decision to publish or preparation of the article. We have no competing interests to declare.

TRAIL REGISTRATION NUMBER

Not applicable.

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.

Effects of a Polymorphism in the Promoter Region of the Follicle-Stimulating Hormone Subunit Beta (FSHB) Gene on Female Reproductive Outcomes

BACKGROUND

Follicle-stimulating hormone (FSH) is essential to the hypothalamic-pituitary-gonadal axis, playing a key role in human reproduction. It is a heterodimer comprised of a hormone-specific β-chain (FSH-β) that is associated with an α-chain. It exerts its biological activities by binding to the FSH receptor (FSHR). The β-subunit, which is encoded by the FSHB gene, is responsible for ensuring binding specificity to the FSHR. There is a promoter polymorphism in this gene, c.-211G>T (rs10835638), upstream of the transcription start site; and in vitro studies have reported that the T allele decreases FSHB transcription in gonadotrophic cells.

AIMS

Investigate the possible effects of the FSHB c.-211G/T polymorphism on hormonal profile and in in vitro fertilization (IVF)/intracytoplasmic sperm injection outcomes in normoovulatory Brazilian women.

METHODS

A cross-sectional study of 140 women (median age = 33 years [CI: 32-34]) with infertility mainly caused by male (n = 85) or tuboperitoneal (n = 55) factors. In this study we evaluated FSH, estradiol, luteinizing hormone (LH), progesterone, prolactin and anti-Mullerian hormone levels, and antral follicle counting (AFC). Genotyping was performed using the TaqMan real-time polymerase chain reaction methodology.

RESULTS

The wild-type allele G was found in 86.4% and the polymorphic allele T in 13.6% of the women respectively. The TT genotype was not found in any women. Women carrying the GT genotype had a poorer response more frequently to controlled ovarian hyperstimulation when compared to individuals with the GG genotype (47.4% vs. 26.5%, p = 0.010), higher LH levels (3.1 IU/mL vs. 2.4 IU/mL, p = <0.001), lower AFC (8.0 vs. 10.0, p = 0.03), oocytes retrieved (3.0 vs. 5.0, p = 0.03), MII (3.0 vs. 4.0, p = 0.02), and embryos (2.0 vs. 3.0, p = 0.02). Despite these findings, no difference was observed in pregnancy rate.

CONCLUSION

Our findings suggest that the FSHB c.-211G/T polymorphism may modestly alter some aspects of the female reproductive system, but they are not associated with significantly different IVF outcomes.

Testosterone and FSH modulate Sertoli cell extracellular secretion: Proteomic analysis

Spermatogenesis is a highly complicated biological process that occurs in the epithelium of the seminiferous tubules. It is regulated by a complex network of endocrine and paracrine factors and by juxtacrine testicular cross-talk. Sertoli cells (SC) play a key role in spermatogenesis due to their production of trophic, differentiation and immune-modulating factors, but many of the molecular pathways of SC action remain controversial and unclear. Over the last two decades, research has focused on extracellular vesicles as an important mechanism of intercellular communication. The aim of this study was to investigate the presence of extracellular vesicles (EVs) in SC and the modulation of their content in SC after FSH and testosterone stimulation. Highly purified porcine pre-pubertal Sertoli cells were isolated according to previously established methods. After 48 h of culture with FSH or FSH + testosterone stimulation, we identified sertolian EVs containing specific mRNAs. Proteomic analysis of EVs content identified 29 proteins under non-stimulatory conditions, most of which were related to receptor binding activity. FSH stimulation induced increases in inhibin-alpha, inhibin-beta, plakoglobin, haptoglobin, D-3-phosphoglycerate dehydrogenase and sodium/potassium-transporting ATPase in sertolian EVs. Testosterone stimulation enhanced the abundance of inhibin-alpha, inhibin-beta, tissue-type plasminogen activator, epidermal growth factor-like protein 8, elongating factor 1-gamma and D-3-phosphoglycerate dehydrogenase. These results are likely to help determine the unknown molecular secretion of Sertoli cells.

Genetic Variation of Follicle-Stimulating Hormone Action Is Associated With Age at Testicular Growth in Boys

CONTEXT

Although genetic factors play a pivotal role in male pubertal timing, genome-wide association studies have identified only a few loci. Genetic variation of follicle-stimulating hormone (FSH) action affects adult reproductive parameters and female pubertal timing.

OBJECTIVE

To investigate whether genetic variation affecting FSH action is associated with onset of puberty in boys.

DESIGN

Cross-sectional and longitudinal study of two cohorts of healthy boys.

SETTING

This was a population-based study.

PATIENTS OR OTHER PARTICIPANTS

Danish (n = 1130) and Chilean (n = 424) boys were followed through puberty and genotyped for FSHB c.-211G>T, FSHR c.-29A>G, and FSHR c.2039G>A.

MAIN OUTCOME MEASURES

Clinical pubertal staging including orchidometry, anthropometry, and serum gonadotropin levels.

RESULTS

Although the cohorts differed markedly (e.g., body composition and genotype frequencies), genetic variation affecting FSH production (FSHB c.-211G>T) was associated with age at pubertal onset, as assessed by testicular enlargement, in both cohorts. The effect appeared further modified by coexistence of genetic variation affecting FSH sensitivity (FSHR c.-29G>A): After correcting for body mass index (BMI), boys with a ligand-receptor variant combination resulting in weak FSH action (i.e., FSHB c.-211GT/TT and FSHR c.-29AA) entered puberty 0.64 years [95% confidence interval (CI), 0.12 to 1.17 years; Denmark] and 0.94 years (95% CI, 0.00 to 1.88 years; Chile) later than boys with the most effective FSH action. Effects explained 1.7% (Denmark) and 1.5% (Chile) of the variance. In addition, BMI z score was negatively associated with pubertal timing (β = -0.35 years in both cohorts), explaining 17.2% (Denmark) and 7.2% (Chile) of the variance.

CONCLUSION

In two ethnically distinct populations, we independently identified an association of two genetic loci with male pubertal timing.

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.

Genetics of Sex Hormone-Binding Globulin and Testosterone Levels in Fertile and Infertile Men of Reproductive Age

Context

Testosterone (T) is a central androgenic hormone, and sex hormone-binding globulin (SHBG) is the major determinant of its bioactivity. There are no acknowledged genetic variants with clear-cut clinical implications, modulating T levels in men.

Objective

To confirm genetic associations of top loci (SHBG, GCKR, SLCO1B1, and JMJD1C) from genome-wide association (GWA) studies for serum SHBG and T.

Design Patients

Groups differing in general and reproductive parameters: young men (n = 540; 19.3 ± 1.8 years), severe idiopathic male infertility patients (n = 641; 31.6 ± 6.0 years), and male partners of pregnant women (n = 324; 31.9 ± 6.6 years). All patients were recruited at the Andrology Centre, Tartu University Hospital, Estonia.

Main Outcome Measures

Genetic associations with reproductive hormones, testicular and sperm parameters (linear regression, additive model); intergroup allele/genotype distribution comparisons.

Results

Associations with serum SHBG levels were robust for SHBG -68 G>A [rs1799941; meta-analysis: P = 3.7 × 10^-14; allelic effect (standard error) = 4.67 (0.62) nmol/L], SHBG +1091 C>T [rs727428; P = 7.3 × 10^-11; -3.74 (0.57)], SHBG Pro185Leu [rs6258; P = 1.2 × 10^-4, -12.2 (3.17)], and GCKR Pro446Leu [rs1260326; P = 1.5 × 10^-4; -2.2 (0.59)]. Measured T concentrations correlated with genetically modulated levels of SHBG (r = 0.48 to 0.74, P < 0.0001), guaranteeing stable availability of free T. Among infertile men, SHBG Pro185Leu substitution showed additional downstream effect on luteinizing hormone [P = 5.1 × 10^-5; -1.66 (0.57) IU/L] and follicle-stimulating hormone [P = 3.4 × 10^-3; -2.48 (1.23) IU/L]. No associations with male reproductive parameters were detected for SHBG Asp327Asn (rs6259), SLCO1B1 Val174Ala (rs4149056), and JMJD1C intronic variant rs7910927.

Conclusions

Claims were replicated and additional associations were detected for four of seven tested GWAS top loci. Perspective clinical investigations of these variants are hypotestosteronemia among aging men and pharmacogenetics of hormone replacement therapy.

Impact of the FSHB gene -211G/T polymorphism on male gonadal function

PURPOSE

The FSHB gene -211G/T polymorphism has been reported to modulate gene expression and to cause inter-individual differences in FSH serum levels in men. This study was undertaken to assess the functional relevance of this polymorphism on gonadotropin and total testosterone serum levels and sperm parameters in men from Eastern Sicily (Italy).

METHODS

To accomplish this, 200 men with abnormal conventional sperm parameters or normozoospermia (according to the parameters of WHO 2010) were genotyped by TaqMan Assay.

RESULTS

The frequency of FSHB -211 T allele was significantly higher (p < 0.005) in patients with altered conventional sperm parameters (18.9% of chromosomes) compared to that observed in men with normozoospermia (10.9% of chromosomes). Decreasing serum levels of FSH and LH were observed across the three FSHB -211 genotype subgroups (p < 0.001 and p < 0.05, respectively). In addition, the FSHB -211G/T polymorphism showed a total testosterone downward trend that became more evident in men with the TT genotype compared to subjects with the GG genotype (p = 0.05). Furthermore, we found a trend towards decreased sperm concentration, total sperm count, sperm forward motility and testicular volume in men with GT and TT genotypes.

CONCLUSIONS

These findings showed that the FSHB -211 G/T polymorphism modulates male gonadal function with a clear influence on hormonal levels and sperm parameters.

CAPSULE

The present study was undertaken to evaluate the distribution of the FSHB -211 G/T in men with normal or abnormal sperm parameters from Southern Italy to assess its functional relevance on the serum levels of reproductive hormones and on sperm parameters in men.

Clinical Applications of Gonadotropins in the Male

The pituitary gonadotropins, luteinizing hormone (LH), and follicle-stimulating hormone (FSH) play a pivotal role in reproduction. The synthesis and secretion of gonadotropins are regulated by complex interactions among several endocrine, paracrine, and autocrine factors of diverse chemical structure. In men, LH regulates the synthesis of androgens by the Leydig cells, whereas FSH promotes Sertoli cell function and thereby influences spermatogenesis. Gonadotropins are complex molecules composed of two subunits, the α- and β-subunit, that are noncovalently associated. Gonadotropins are decorated with glycans that regulate several functions of the protein including folding, heterodimerization, stability, transport, conformational maturation, efficiency of heterodimer secretion, metabolic fate, interaction with their cognate receptor, and selective activation of signaling pathways. A number of congenital and acquired abnormalities lead to gonadotropin deficiency and hypogonadotropic hypogonadism, a condition amenable to treatment with exogenous gonadotropins. Several natural and recombinant preparations of gonadotropins are currently available for therapeutic purposes. The difference between natural and the currently available recombinant preparations (which are massively produced in Chinese hamster ovary cells for commercial purposes) mainly lies in the abundance of some of the carbohydrates that conform the complex glycans attached to the protein core. Whereas administration of exogenous gonadotropins in patients with isolated congenital hypogonadotropic hypogonadism is a well recognized therapeutic approach, their role in treating men with normogonadotropic idiopathic infertility is still controversial. This chapter concentrates on the main structural and functional features of the gonadotropin hormones and how basic concepts have been translated into the clinical arena to guide therapy for gonadotropin deficit in males.

Genetic evidence that lower circulating FSH levels lengthen menstrual cycle, increase age at menopause and impact female reproductive health

STUDY QUESTION

How does a genetic variant in the FSHB promoter, known to alter FSH levels, impact female reproductive health?

SUMMARY ANSWER

The T allele of the FSHB promoter polymorphism (rs10835638; c.-211G>T) results in longer menstrual cycles and later menopause and, while having detrimental effects on fertility, is protective against endometriosis.

WHAT IS KNOWN ALREADY

The FSHB promoter polymorphism (rs10835638; c.-211G>T) affects levels of FSHB transcription and, as a result, circulating levels of FSH. FSH is required for normal fertility and genetic variants at the FSHB locus are associated with age at menopause and polycystic ovary syndrome (PCOS).

STUDY DESIGN, SIZE, DURATION

We used cross-sectional data from the UK Biobank to look at associations between the FSHB promoter polymorphism and reproductive traits, and performed a genome-wide association study (GWAS) for length of menstrual cycle.

PARTICIPANTS/MATERIALS, SETTING, METHODS

We included white British individuals aged 40-69 years in 2006-2010, in the May 2015 release of genetic data from UK Biobank. We tested the FSH-lowering T allele of the FSHB promoter polymorphism (rs10835638; c.-211G>T) for associations with 29, mainly female, reproductive phenotypes in up to 63 350 women and 56 608 men. We conducted a GWAS in 9534 individuals to identify genetic variants associated with length of menstrual cycle.

MAIN RESULTS AND THE ROLE OF CHANCE

The FSH-lowering T allele of the FSHB promoter polymorphism (rs10835638; MAF 0.16) was associated with longer menstrual cycles [0.16 SD (c. 1 day) per minor allele; 95% confidence interval (CI) 0.12-0.20; P = 6 × 10(-16)], later age at menopause (0.13 years per minor allele; 95% CI 0.04-0.22; P = 5.7 × 10(-3)), greater female nulliparity [odds ratio (OR) = 1.06; 95% CI 1.02-1.11; P = 4.8 × 10(-3)] and lower risk of endometriosis (OR = 0.79; 95% CI 0.69-0.90; P = 4.1 × 10(-4)). The FSH-lowering T allele was not associated with other female reproductive illnesses or conditions in our study and we did not replicate associations with male infertility or PCOS. In the GWAS for menstrual cycle length, only variants near the FSHB gene reached genome-wide significance (P < 5 × 10(-9)).

LIMITATIONS, REASONS FOR CAUTION

The data included might be affected by recall bias. Cycle length was not available for 25% of women still cycling (1% did not answer, 6% did not know and for 18% cycle length was recorded as 'irregular'). Women with a cycle length recorded were aged over 40 and were approaching menopause; however, we did not find evidence that this affected the results. Many of the groups with illnesses had relatively small sample sizes and so the study may have been under-powered to detect an effect.

WIDER IMPLICATIONS OF THE FINDINGS

We found a strong novel association between a genetic variant that lowers FSH levels and longer menstrual cycles, at a locus previously robustly associated with age at menopause. The variant was also associated with nulliparity and endometriosis risk. These findings should now be verified in a second independent group of patients. We conclude that lifetime differences in circulating levels of FSH between individuals can influence menstrual cycle length and a range of reproductive outcomes, including menopause timing, infertility, endometriosis and PCOS.

STUDY FUNDING/COMPETING INTERESTS

None.

TRIAL REGISTRATION NUMBER

Not applicable.

Environmentally Induced Epigenetic Transgenerational Inheritance of Reproductive Disease

Reproductive disease and fertility issues have dramatically increased in the human population over the last several decades, suggesting environmental impacts. Epigenetics provides a mechanistic link by which an organism can respond to environmental factors. Interestingly, environmentally induced epigenetic alterations in the germ line can promote aberrant gene expression and disease generationally. Environmentally induced epigenetic transgenerational inheritance is defined as germ-line transmission of altered epigenetic information between generations in the absence of continued environmental exposures. This form of nongenetic inheritance has been shown to directly influence fertility and reproductive disease. This review describes the studies in a variety of species that impact reproductive disease and abnormalities. Observations suggest serious attention be paid to the possibility that ancestral exposures to environmental insults promotes transgenerational inheritance of reproductive disease susceptibility. Environmentally induced epigenetic transgenerational inheritance appears to be an important contributing factor to reproductive disease in many organisms, including humans.

Naturally occurring genetic mutations in the 5'-upstream regulatory region of bovine FSHB generate a novel cis-regulatory element that affects its expression

We previously reported that numerous naturally occurring genetic mutations in the 5'-upstream regulatory region (5'-URR) of the bovine follicle-stimulating hormone beta-subunit gene (FSHB) were associated with reduced serum follicle-stimulating hormone (FSH) levels, poor-quality semen and low fertility in bulls. In addition, two different FSHB mRNA transcripts resulting from the linked mutations of genomic DNA were discovered in mutation-bearing bull pituitaries. Here, using electrophoretic mobility shift assay, we identified c.-1539_-1538delGGinsTTAACT mutations in the 5'-URR that generated a novel cis-regulatory element in bovine FSHB. Moreover, this novel element seemed to play a role in repressing FSHB transcription based on a promoter activity analysis in LβT2 gonadotrope cells. Quantitative assays of FSHB mRNA in the bovine pituitaries suggested that the levels of FSHB wild-type transcripts in the mutation-bearing bulls were significantly lower (P < 0.05) than in those of bulls without FSHB genetic mutations and that the levels of FSHB-mutated transcripts were significantly lower (P < 0.05) than that of wild-type transcripts in the mutation-bearing bulls. Altogether, our results suggest that decreased serum FSH levels and male fertility in bulls with the c.-1539_-1538delGGinsTTAACT mutation likely result from the alteration of cis-regulatory elements and induction of FSHB transcription.

FSHB -211G>T stratification for follicle-stimulating hormone treatment of male infertility patients: making the case for a pharmacogenetic approach in genetic functional secondary hypogonadism

Male infertility contributes to a substantial share to couple infertility. Despite scientific efforts, most cases of male infertility remain 'idiopathic' and male-specific therapeutic options are sparse. Given the crucial role of the follicle-stimulating hormone (FSH) for spermatogenesis, FSH is used empirically to improve semen parameters. Furthermore, a recently updated Cochrane review points to a beneficial effect of FSH treatment in idiopathic infertile men on spontaneous pregnancy rates. However, since response to FSH varies strongly even in selected patients and given the lack of powerful evidence of FSH treatment regimens, intra-cytoplasmic spermatozoa injection (ICSI) is widely used in idiopathic male infertility, though the treatment burden is high for the couple and it entails considerable costs and some risks. Single nucleotide polymorphisms (SNPs) within FSH ligand/receptor genes (FSHB/FSHR), significantly influencing reproductive parameters in men, represent promising candidates to serve as pharmacogenetic markers to improve prediction of response to FSH. However, there is an evident lack of information which patients should be treated and how many patients in an andrological outpatient clinic would be eligible for such a treatment, a crucial decision criterion for clinicians and also pharmaceutical industry to start such a pharmacogenetic intervention therapy. After screening our andrological patient cohort, we present a realistic scenario and a basis for further prospective studies using FSH in idiopathic infertile men.