Infertility affects around 7% of men worldwide. Idiopathic non-obstructive azoospermia (NOA) is defined as the absence of spermatozoa in the ejaculate due to failed spermatogenesis. There is a high ...probability that NOA is caused by rare genetic defects. In this study, whole-exome sequencing (WES) was applied to two Estonian brothers diagnosed with NOA and Sertoli cell-only syndrome (SCOS). Compound heterozygous loss-of-function (LoF) variants in FANCM (Fanconi anemia complementation group M) were detected as the most likely cause for their condition. A rare maternally inherited frameshift variant p.Gln498Thrfs∗7 (rs761250416) and a previously undescribed splicing variant (c.4387−10A>G) derived from the father introduce a premature STOP codon leading to a truncated protein. FANCM exhibits enhanced testicular expression. In control subjects, immunohistochemical staining localized FANCM to the Sertoli and spermatogenic cells of seminiferous tubules with increasing intensity through germ cell development. This is consistent with its role in maintaining genomic stability in meiosis and mitosis. In the individual with SCOS carrying bi-allelic FANCM LoF variants, none or only faint expression was detected in the Sertoli cells. As further evidence, we detected two additional NOA-affected case subjects with independent FANCM homozygous nonsense variants, one from Estonia (p.Gln1701∗; rs147021911) and another from Portugal (p.Arg1931∗; rs144567652). The study convincingly demonstrates that bi-allelic recessive LoF variants in FANCM cause azoospermia. FANCM pathogenic variants have also been linked with doubled risk of familial breast and ovarian cancer, providing an example mechanism for the association between infertility and cancer risk, supported by published data on Fancm mutant mouse models.
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
(
) region, combined with gene dosage analysis of the multicopy
, and
genes 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
inversion, destabilizing the
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
). 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.
The follicle stimulating hormone (FSH), luteinizing hormone (LH) and chorionic gonadotropin (HCG) play a critical role in human reproduction. Despite the common evolutionary ancestry and functional ...relatedness of the gonadotropin hormone beta (GtHB) genes, the single-copy FSHB (at 11p13) and the multi-copy LHB/CGB genes (at 19q13.32) exhibit locus-specific differences regarding their genomic context, evolution, genetic variation and expressional profile. FSHB represents a conservative vertebrate gene with a unique function and it is located in a structurally stable gene-poor region. In contrast, the primate-specific LHB/CGB gene cluster is located in a gene-rich genomic context and demonstrates an example of evolutionary young and unstable genomic region. The gene cluster is shaped by a constant balance between selection that acts on specific functions of the loci and frequent gene conversion events among duplicons. As the transcription of the GtHB genes is rate-limiting in the assembly of respective hormones, the genomic and genetic context of the FSHB and the LHB/CGB genes largely affects the profile of the hormone production.
Follicle-Stimulating Hormone Receptor (FSHR) -29G/A polymorphism (rs1394205) was reported to modulate gene expression and reproductive parameters in women, but data in men is limited. We aimed to ...bring evidence to the effect of FSHR -29G/A variants in men. In Baltic young male cohort (n = 982; Estonians, Latvians, Lithuanians; aged 20.2 ± 2.0 years), the FSHR -29 A-allele was significantly associated with higher serum FSH (linear regression: effect 0.27 IU/L; P = 0.0019, resistant to Bonferroni correction for multiple testing) and showed a non-significant trend for association with higher LH (0.19 IU/L) and total testosterone (0.93 nmol/L), but reduced Inhibin B (-7.84 pg/mL) and total testes volume (effect -1.00 mL). Next, we extended the study and tested the effect of FSHR gene haplotypes determined by the allelic combination of FSHR -29G/A and a well-studied variant c.2039 A/G (Asn680Ser, exon 10). Among the FSHR -29A/2039G haplotype carriers (A-Ser; haplotype-based linear regression), this genetic effect was enhanced for FSH (effect 0.40 IU/L), Inhibin B (-16.57 pg/mL) and total testes volume (-2.34 mL). Finally, we estimated the total contribution of three known FSH-action modulating SNPs (FSHB -211G/T; FSHR -29G/A, c.2039 A/G) to phenotypic variance in reproductive parameters among young men. The major FSH-action modulating SNPs explained together 2.3%, 1.4%, 1.0 and 1.1% of the measured variance in serum FSH, Inhibin B, testosterone and total testes volume, respectively. In contrast to the young male cohort, neither FSHR -29G/A nor FSHR haplotypes appeared to systematically modulate the reproductive physiology of oligozoospermic idiopathic infertile patients (n = 641, Estonians; aged 31.5 ± 6.0 years). In summary, this is the first study showing the significant effect of FSHR -29G/A on male serum FSH level. To account for the genetic effect of known common polymorphisms modulating FSH-action, we suggest haplotype-based analysis of FSHR SNPs (FSHR -29G/A, c.2039 A/G) in combination with FSHB -211G/T testing.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Context:
A polymorphism in the FSHB promoter (−211G>T, rs10835638) was shown to influence male serum FSH levels, whereas a polymorphism in the FSH receptor gene (FSHR; 2039A>G, rs6166) was previously ...shown to be associated with FSH levels in women only.
Objective:
The objective of the study was to analyze the effects of both FSHB −211G>T and FSHR 2039A>G on male reproductive parameters.
Design and Setting:
A total of 1213 German men attending an infertility clinic were genotyped by TaqMan assay.
Patients:
Patients included male partners in infertile couples without known causes for male infertility.
Main Outcome Measures:
An association analysis of single and combined single-nucleotide polymorphism genotypes with clinical parameters was performed.
Results:
The FSHB −211G>T T-allele showed significant dosage effects for FSH (−0.51 U/liter per T-allele), LH (0.28 U/liter), and bitesticular volume (−3.2 ml). Statistical significance was enhanced severalfold after a meta-analysis comprising 3017 men. TT carriers were significantly more prevalent among men with lower sperm counts. The FSHR 2039A>G G-allele exhibited nonsignificant trends for associations with higher FSH and reduced testicular volumes. However, in the combined model, FSHR 2039A>G significantly modulated the more dominant effect of FSHB −211G>T on serum FSH and testicular volume among the T-allele carriers.
Conclusions:
By analyzing both single-nucleotide polymorphisms for the first time, we convincingly show that indeed FSHR 2039A>G has an effect also in males. In the proposed model of the combined effects, FSHB −211G>T acts strongly on male reproductive parameters, whereas the FSHR 2039A>G effects were approximately 2–3 times smaller. Clinically this is of importance because oligozoospermic patients carrying unfavorable variants affecting FSH action may benefit from FSH treatment.
Objective
The study aimed to identify the genetic basis of partial gonadal dysgenesis (PGD) in a non‐consanguineous family from Estonia.
Patients
Cousins P (proband) 1 (12 years; 46,XY) and P2 ...(18 years; 46,XY) presented bilateral cryptorchidism, severe penoscrotal hypospadias, low bitesticular volume and azoospermia in P2. Their distant relative, P3 (30 years; 46,XY), presented bilateral cryptorchidism and cryptozoospermia.
Design
Exome sequencing was targeted to P1‐P3 and five unaffected family members.
Results
P1‐P2 were identified as heterozygous carriers of NR5A1 c.991‐1G > C. NR5A1 encodes the steroidogenic factor‐1 essential in gonadal development and specifically expressed in adrenal, spleen, pituitary and testes. Together with a previous PGD case from Belgium (Robevska et al 2018), c.991‐1G > C represents the first recurrent NR5A1 splice‐site mutation identified in patients. The majority of previous reports on NR5A1 mutation carriers have not included phenotype‐genotype data of the family members. Segregation analysis across three generations showed incomplete penetrance (<50%) and phenotypic variability among the carriers of NR5A1 c.991‐1G > C. The variant pathogenicity was possibly modulated by rare heterozygous variants inherited from the other parent, OTX2 p.P134R (P1) or PROP1 c.301_302delAG (P2). For P3, the pedigree structure supported a distinct genetic cause. He carries a previously undescribed likely pathogenic variant SOS1 p.Y136H. SOS1, critical in Ras/MAPK signalling and foetal development, is a strong novel candidate gene for cryptorchidism.
Conclusions
Detailed genetic profiling facilitates counselling and clinical management of the probands, and supports unaffected mutation carriers in the family for their reproductive decision making.
Abstract
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.
BACKGROUND No polymorphisms affecting serum FSH levels have been described in the human FSHB gene. We have identified a potential regulatory single nucleotide polymorphism (SNP, rs10835638; G/T) 211 ...bp upstream from the FSHB mRNA transcription start-site, located within a highly conserved region among placental mammals. We aimed to determine the correlation of carrier status of rs10835638 alternative alleles with serum FSH level in men, and testicular and hormonal parameters. METHODS A quantitative genetic association study using a cohort of healthy men (n = 554; age 19.2 ± 1.7 years) visiting the Centre of Andrology, Tartu University Hospital, Estonia. RESULTS Rs10835638 (allele frequencies: G 87.6%, T 12.4%) was significantly associated with serum FSH level (analysis of variance: F = 13.0, P = 0.0016, df = 1; regression testing for a linear trend: P = 0.0003). Subjects with the GG genotype exhibited higher FSH levels (3.37 ± 1.79 IU/l, n = 423) compared with heterozygotes (2.84 ± 1.54 IU/l, n = 125) (P = 0.0005), the group of T-allele carriers (GT+TT, 2.78 ± 1.51 IU/l, n = 131) (P = 0.0005) and TT-homozygotes (2.02 ± 0.81 IU/L, n = 6) (P = 0.031). Rs10835638 was also associated with significant (P < 0.05) reduction in free testosterone index and testes volume, but increased semen volume, sex hormone-binding globulin, serum testosterone and estradiol. LH and inhibin-B levels did not differ significantly between groups. CONCLUSIONS The identification of a regulatory SNP in FSHB promoter paves the way to study the effect of constitutively low FSH on male health and fertility. As FSH contributes to follicular development and sex steroid production in women, the role of this FSHB variant in female reproductive success is still to be addressed.
Pharmacogenetics of follicle-stimulating hormone action Laan, Maris; Grigorova, Marina; Huhtaniemi, Ilpo T
Current opinion in endocrinology, diabetes and obesity./Current opinion in endocrinology, diabetes and obesity
19, Številka:
3
Journal Article
Recenzirano
Odprti dostop
To review the current knowledge of genetic variants in the two genes affecting the individual responsiveness to follicle-stimulating hormone (FSH) action-the FSH beta-subunit (FSHB) and the FSH ...receptor (FSHR), as well as the pharmacogenetic ramifications of the findings.
Four common variants in the FSHB and the FSHR genes were shown to exhibit significant effect on FSH action: linked FSHR variants Thr307Ala and Asn680Ser determining common receptor isoforms, and gene expression affecting polymorphisms FSHR -29G/A and FSHB -211G/T. In women, the FSHR Thr307Ala/Asn680Ser polymorphisms show consistent predictive value for estimating the most optimal recombinant FSH dosage in controlled ovarian hyperstimulation (COH). The same variants exhibit a potential for the pharmacogenetic assessment of the treatment of polycystic ovarian syndrome. The FSHR -29G/A variant was also shown to contribute to ovarian response to COH. Pilot studies have suggested the FSHB -211 TT homozygous oligozoospermic men with genetically determined low concentration of FSH, as potentially the best responders to FSH treatment; furthermore, modulation of this response by FSHR polymorphisms is possible.
Genetic variants in FSHB and FSHR exhibit a potential for pharmacogenetic applications in selecting appropriate treatment options (timing and dosage) in male and female conditions requiring or benefiting from FSH therapy.
Human RBMY1 genes are located in four variable-sized clusters on the Y chromosome, expressed in male germ cells and possibly associated with sperm motility. We have re-investigated the mutational ...background and evolutionary history of the RBMY1 copy number distribution in worldwide samples and its relevance to sperm parameters in an Estonian cohort of idiopathic male factor infertility subjects. We estimated approximate RBMY1 copy numbers in 1218 1000 Genomes Project phase 3 males from sequencing read-depth, then chose 14 for valid ation by multicolour fibre-FISH. These fibre-FISH samples provided accurate calibration standards for the entire panel and led to detailed insights into population variation and mutational mechanisms. RBMY1 copy number worldwide ranged from 3 to 13 with a mode of 8. The two larger proximal clusters were the most variable, and additional duplications, deletions and inversions were detected. Placing the copy number estimates onto the published Y-SNP-based phylogeny of the same samples suggested a minimum of 562 mutational changes, translating to a mutation rate of 2.20 × 10-3 (95% CI 1.94 × 10-3 to 2.48 × 10-3) per father-to-son Y-transmission, higher than many short tandem repeat (Y-STRs), and showed no evidence for selection for increased or decreased copy number, but possible copy number stabilizing selection. An analysis of RBMY1 copy numbers among 376 infertility subjects failed to replicate a previously reported association with sperm motility and showed no significant effect on sperm count and concentration, serum follicle stimulating hormone (FSH), luteinizing hormone (LH) and testosterone levels or testicular and semen volume. These results provide the first in-depth insights into the structural rearrangements underlying RBMY1 copy number variation across diverse human lineages.
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