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. 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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.