Toward clinical exomes in diagnostics and management of male infertility.

Infertility, affecting ∼10% of men, is predominantly caused by primary spermatogenic failure (SPGF). We screened likely pathogenic and pathogenic (LP/P) variants in 638 candidate genes for male infertility in 521 individuals presenting idiopathic SPGF and 323 normozoospermic men in the ESTAND cohort. Molecular diagnosis was reached for 64 men with SPGF (12%), with findings in 39 genes (6%). The yield did not differ significantly between the subgroups with azoospermia (20/185, 11%), oligozoospermia (18/181, 10%), and primary cryptorchidism with SPGF (26/155, 17%). Notably, 19 of 64 LP/P variants (30%) identified in 28 subjects represented recurrent findings in this study and/or with other male infertility cohorts. NR5A1 was the most frequently affected gene, with seven LP/P variants in six SPGF-affected men and two normozoospermic men. The link to SPGF was validated for recently proposed candidate genes ACTRT1, ASZ1, GLUD2, GREB1L, LEO1, RBM5, ROS1, and TGIF2LY. Heterozygous truncating variants in BNC1, reported in female infertility, emerged as plausible causes of severe oligozoospermia. Data suggested that several infertile men may present congenital conditions with less pronounced or pleiotropic phenotypes affecting the development and function of the reproductive system. Genes regulating the hypothalamic-pituitary-gonadal axis were affected in >30% of subjects with LP/P variants. Six individuals had more than one LP/P variant, including five with two findings from the gene panel. A 4-fold increased prevalence of cancer was observed in men with genetic infertility compared to the general male population (8% vs. 2%; p = 4.4 × 10-3). Expanding genetic testing in andrology will contribute to the multidisciplinary management of SPGF.

Undiagnosed RASopathies in infertile men.

RASopathies are syndromes caused by congenital defects in the Ras/mitogen-activated protein kinase (MAPK) pathway genes, with a population prevalence of 1 in 1,000. Patients are typically identified in childhood based on diverse characteristic features, including cryptorchidism (CR) in >50% of affected men. As CR predisposes to spermatogenic failure (SPGF; total sperm count per ejaculate 0-39 million), we hypothesized that men seeking infertility management include cases with undiagnosed RASopathies. Likely pathogenic or pathogenic (LP/P) variants in 22 RASopathy-linked genes were screened in 521 idiopathic SPGF patients (including 155 CR cases) and 323 normozoospermic controls using exome sequencing. All 844 men were recruited to the ESTonian ANDrology (ESTAND) cohort and underwent identical andrological phenotyping. RASopathy-specific variant interpretation guidelines were used for pathogenicity assessment. LP/P variants were identified in PTPN11 (two), SOS1 (three), SOS2 (one), LZTR1 (one), SPRED1 (one), NF1 (one), and MAP2K1 (one). The findings affected six of 155 cases with CR and SPGF, three of 366 men with SPGF only, and one (of 323) normozoospermic subfertile man. The subgroup "CR and SPGF" had over 13-fold enrichment of findings compared to controls (3.9% vs. 0.3%; Fisher's exact test, p = 5.5 × 10-3). All ESTAND subjects with LP/P variants in the Ras/MAPK pathway genes presented congenital genitourinary anomalies, skeletal and joint conditions, and other RASopathy-linked health concerns. Rare forms of malignancies (schwannomatosis and pancreatic and testicular cancer) were reported on four occasions. The Genetics of Male Infertility Initiative (GEMINI) cohort (1,416 SPGF cases and 317 fertile men) was used to validate the outcome. LP/P variants in PTPN11 (three), LZTR1 (three), and MRAS (one) were identified in six SPGF cases (including 4/31 GEMINI cases with CR) and one normozoospermic man. Undiagnosed RASopathies were detected in total for 17 ESTAND and GEMINI subjects, 15 SPGF patients (10 with CR), and two fertile men. Affected RASopathy genes showed high expression in spermatogenic and testicular somatic cells. In conclusion, congenital defects in the Ras/MAPK pathway genes represent a new congenital etiology of syndromic male infertility. Undiagnosed RASopathies were especially enriched among patients with a history of cryptorchidism. Given the relationship between RASopathies and other conditions, infertile men found to have this molecular diagnosis should be evaluated for known RASopathy-linked health concerns, including specific rare malignancies.

Microdeletions and microduplications linked to severe congenital disorders in infertile men.

Data on the clinical validity of DNA copy number variants (CNVs) in spermatogenic failure (SPGF) is limited. This study analyzed the genome-wide CNV profile in 215 men with idiopathic SPGF and 62 normozoospermic fertile men, recruited at the Andrology Clinic, Tartu University Hospital, Estonia. A two-fold higher representation of > 1 Mb CNVs was observed in men with SPGF (13%, n = 28) compared to controls (6.5%, n = 4). Seven patients with SPGF were identified as carriers of microdeletions (1q21.1; 2.4 Mb) or microduplications (3p26.3, 1.1 Mb; 7p22.3-p22.2, 1.56 Mb; 10q11.22, 1.42 Mb, three cases; Xp22.33; 2.3 Mb) linked to severe congenital conditions. Large autosomal CNV carriers had oligozoospermia, reduced or low-normal bitesticular volume (22-28 ml). The 7p22.3-p22.2 microduplication carrier presented mild intellectual disability, neuropsychiatric problems, and short stature. The Xp22.33 duplication at the PAR1/non-PAR boundary, previously linked to uterine agenesis, was detected in a patient with non-obstructive azoospermia. A novel recurrent intragenic deletion in testis-specific LRRC69 was significantly overrepresented in patients with SPGF compared to the general population (3.3% vs. 0.85%; χ2 test, OR = 3.9 [95% CI 1.8-8.4], P = 0.0001). Assessment of clinically valid CNVs in patients with SPGF will improve their management and counselling for general and reproductive health, including risk of miscarriage and congenital disorders in future offspring.

The European Academy of Andrology (EAA) ultrasound study on healthy, fertile men: An overview on male genital tract ultrasound reference ranges.

BACKGROUND: So far, male genital tract color-Doppler ultrasound (MGT-CDUS) was not standardized. Recently, the European Academy of Andrology (EAA) published the results of a multicenter study assessing the CDUS characteristics of healthy-fertile men (HFM) to obtain normative parameters. OBJECTIVES: To report the EAA US study (i) standard operating procedures (SOPs) for assessing MGT-CDUS, (ii) main MGT-CDUS normative parameters, and (iii) compare the EAA and previously published "normal" CDUS values. METHODS: A cohort of 248 HFM (35.3 ± 5.9 years) was studied, evaluating MGT-CDUS before and after ejaculation following SOPs. RESULTS: SOPs for MGT-CDUS assessment are summarized here. All subjects underwent scrotal CDUS and 188 men underwent transrectal ultrasound before and after ejaculation. The main CDUS reference ranges and characteristics of the HFM-MGT are reported here. The mean testicular volume was ∼17 mL. The lower limit for right and left testis was 12 and 11 mL, defining testicular hypotrophy. The upper limit for epididymal head, body, tail, and vas deferens was 11.5, 5, 6, and 4.5 mm, respectively. Testicular and epididymal arterial reference ranges are reported. The EAA varicocoele classification is reported. CDUS-varicocoele was detected in ∼37% of men. Prostate mean volume was ∼25 mL, while lower and upper limits were 15 and 35 mL, defining hypotrophy and enlargement, respectively. Prostate arterial reference ranges are reported. Prostate calcifications and inhomogeneity were frequent; midline prostatic cysts were rare and small. Ejaculatory duct abnormalities were absent. The upper limit for periprostatic venous plexus was 4.5 mm. Lower and upper limits of seminal vesicles (SV) anterior-posterior diameter were 6 and 16 mm, defining hypotrophy or dilation, respectively. Seminal vesicle volume and ejection fraction reference ranges are reported. SV-US abnormalities were rare. Deferential ampullas upper limit was 6 mm. A discussion on the EAA and previously published "normal" CDUS values is reported here. CONCLUSIONS: The EAA findings will help in reproductive and general male health management.

The European Academy of Andrology (EAA) ultrasound study on healthy, fertile men: Prostate-vesicular transrectal ultrasound reference ranges and associations with clinical, seminal and biochemical characteristics.

BACKGROUND: Transrectal ultrasound (TRUS) parameters are not standardized, especially in men of reproductive age. Hence, the European Academy of Andrology (EAA) promoted a multicenter study to assess the TRUS characteristics of healthy-fertile men (HFM) to establish normative parameters. OBJECTIVES: To report and discuss the prostate and seminal vesicles (SV) reference ranges and characteristics in HFM and their associations with clinical, seminal, biochemical parameters. METHODS: 188 men (35.6 ± 6.0 years) from a cohort of 248 HFM were studied, evaluating, on the same day, clinical, biochemical, seminal, TRUS parameters following Standard Operating Procedures. RESULTS: TRUS reference ranges and characteristics of the prostate and SV of HFM are reported herein. The mean PV was ∼25 ml. PV lower and upper limits were 15 and 35 ml, defining prostate hypotrophy and enlargement, respectively. PV was positively associated with age, waistline, current smoking (but not with T levels), seminal volume (and negatively with seminal pH), prostate inhomogeneity, macrocalcifications, calcification size and prostate arterial parameters, SV volume before and after ejaculation, deferential and epididymal size. Prostate calcifications and inhomogeneity were frequent, while midline prostatic cysts were rare and small. Ejaculatory duct abnormalities were absent. Periprostatic venous plexus size was positively associated with prostate calcifications, SV volume and arterial peak systolic velocity. Lower and upper limits of SV anterior-posterior diameter after ejaculation were 6 and 16 mm, defining SV hypotrophy or dilation, respectively. SV total volume before ejaculation and delta SV total volume (DSTV) positively correlated with ejaculate volume, and DSTV correlated positively with sperm progressive motility. SV total volume after ejaculation was associated negatively with SV ejection fraction and positively with distal ampullas size. SV US abnormalities were rare. No association between TRUS and time to pregnancy, number of children or history of miscarriage was observed. CONCLUSIONS: The present findings will help in better understanding male infertility pathophysiology and the meaning of specific TRUS findings.

Mycoplasma genitalium Provokes Seminal Inflammation among Infertile Males.

The impact of sexually transmitted infections (STI) on male fertility is controversial. Aims: To investigate the prevalence of urethritis-associated STIs (chlamydia, gonorrhoeae, Mycoplasma genitalium, trichomoniasis) among infertile males; to analyze the effect of STIs on semen parameters and blood PSA. Case-control study. Study group (n = 2000): males with fertility problems or desire for fertility check. Control group (n = 248): male partners of pregnant women. Analyses: polymerase chain reaction for STI, seminal interleukin 6 (IL-6), semen and fractionated urine, blood analyses (PSA, reproductive hormones). The prevalence of M. genitalium and chlamydia in the study group was 1.1% and 1.2%, respectively. The prevalence of chlamydia in the control group was 1.6%, while there were no M. genitalium cases. No cases with gonorrhoeae or trichomoniasis or combined infections were observed in neither group. There was a higher seminal concentration of neutrophils and IL-6 among M. genitalium positives compared with STI negatives. There was a trend toward a lower total count of spermatozoa and progressive motility among STI positives. No impact of STIs on PSA was found. The prevalence of STIs among infertile males is low. M. genitalium is associated with seminal inflammation. The impact of STIs on semen parameters deserves further investigations.

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.

The European Academy of Andrology (EAA) ultrasound study on healthy, fertile men: clinical, seminal and biochemical characteristics.

BACKGROUND: Infertility affects 7%-12% of men, and its etiology is unknown in half of cases. To fill this gap, use of the male genital tract color-Doppler ultrasound (MGT-CDUS) has progressively expanded. However, MGT-CDUS still suffers from lack of standardization. Hence, the European Academy of Andrology (EAA) has promoted a multicenter study ("EAA ultrasound study") to assess MGT-CDUS characteristics of healthy, fertile men to obtain normative parameters. OBJECTIVES: To report (a) the development and methodology of the "EAA ultrasound study," (b) the clinical characteristics of the cohort of healthy, fertile men, and (c) the correlations of both fertility history and seminal features with clinical parameters. METHODS: A cohort of 248 healthy, fertile men (35.3 ± 5.9 years) was studied. All subjects were asked to undergo, within the same day, clinical, biochemical, and seminal evaluation and MGT-CDUS before and after ejaculation. RESULTS: The clinical, seminal, and biochemical characteristics of the cohort have been reported here. The seminal characteristics were consistent with those reported by the WHO (2010) for the 50th and 5th centiles for fertile men. Normozoospermia was observed in 79.6% of men, while normal sperm vitality was present in almost the entire sample. Time to pregnancy (TTP) was 3.0[1.0-6.0] months. TTP was negatively correlated with sperm vitality (Adj.r =-.310, P = .011), but not with other seminal, clinical, or biochemical parameters. Sperm vitality and normal morphology were positively associated with fT3 and fT4 levels, respectively (Adj.r = .244, P < .05 and Adj.r = .232, P = .002). Sperm concentration and total count were negatively associated with FSH levels and positively, along with progressive motility, with mean testis volume (TV). Mean TV was 20.4 ± 4.0 mL, and the lower reference values for right and left testes were 15.0 and 14.0 mL. Mean TV was negatively associated with gonadotropin levels and pulse pressure. Varicocoele was found in 33% of men. CONCLUSIONS: The cohort studied confirms the WHO data for all semen parameters and represents a reference with which to assess MGT-CDUS normative parameters.

Evolutionary and functional analysis of RBMY1 gene copy number variation on the human Y chromosome.

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.

Chromosomal scan of single sperm cells by combining fluorescence-activated cell sorting and next-generation sequencing.

PURPOSE: The purpose of this study was to develop a feasible approach for single sperm isolation and chromosome analysis by next-generation sequencing (NGS). METHODS: Single sperm cells were isolated from semen samples of normozoospermic male and an infertile reciprocal translocation (RcT) carrier with the 46,XY,t(7;13)(p12;q12.1) karyotype using the optimized fluorescence-activated cell sorting (FACS) technique. Genome profiling was performed using NGS. RESULTS: Following whole-genome amplification, NGS, and quality control, the final chromosome analysis was performed on 31 and 6 single cell samples derived from the RcT carrier and normozoospermic male, respectively. All sperm cells from normozoospermic male showed a normal haploid 23-chromosome profile. For the RcT carrier, the sequencing data revealed that 64.5% of sperm cells harbored different variants of chromosome aberrations, involving deletion of 7p or 7q, duplication of 7p, and duplication of 13q, which is concordant with the expected chromosome segregation patterns observed in balanced translocation carriers. In one sample, a duplication of 9q was also detected. CONCLUSIONS: We optimized FACS protocol for simple and efficient isolation of single human sperm cells that subsequently enabled a successful genome-wide chromosome profiling and identification of segmental aneuploidies from these individual cells, following NGS analysis. This approach may be useful for analyzing semen samples of infertile men or chromosomal aberration carriers to facilitate the reproductive risk assessment.

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.

Reproductive physiology in young men is cumulatively affected by FSH-action modulating genetic variants: FSHR -29G/A and c.2039 A/G, FSHB -211G/T.

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.

Follicle-stimulating hormone receptor gene haplotypes and male infertility in estonian population and meta-analysis.

Follicle-stimulating hormone (FSH) is crucial for male fertility and it exerts its effects via a gonad-specific receptor (FSHR). In the present study, the common G-29A, A919G, and A2039G polymorphisms in the FSHR gene were analysed in 150 (36 non-obstructive azoospermia and 114 individuals with oligozoospermia) patients and 208 normozoospermic men. The results showed that the FSHR polymorphisms were not associated with either azoo- or oligozoospermia as the distributions of alleles, genotypes, and haplotypes among patients and controls were similar. Amongst normozoospermic men, those carrying at least one minor A allele (GA and AA genotypes) of the G-29A polymorphism had a smaller mean testicular volume compared to men with GG homozygosity (25.8 ml vs. 27.4 ml, respectively; P=0.013). In a subsequent meta-analysis combining our data with previous studies, the G-29-A919-A2039 haplotype was shown to be more prevalent in normozoospermic men than in azoospermic patients (38.4% vs. 33.9%, respectively; chi(2)test, P=0.045), indicating that this haplotype may be a protective factor against male sterility. In conclusion, we suggest that FSHR haplotypes are not considerable risk factors for spermatogenic failure. The protective nature of G-29-A919-A2039 haplotype cannot be concluded without additional studies.

Increased Prevalance of the -211 T allele of follicle stimulating hormone (FSH) beta subunit promoter polymorphism and lower serum FSH in infertile men.

CONTEXT: The human FSHB promoter polymorphism (rs10835638; -211 G/T) has been associated with serum FSH in a cohort of young Estonian men. The minor allele carriers had reduced serum FSH (15.7% in GT heterozygotes; 40% in TT homozygotes) compared with GG homozygotes. OBJECTIVE: Because FSH is essential for normal spermatogenesis and fertility, we speculated that abnormalities in FSH action could contribute to male infertility. We sought to study whether genetically inherited constitutively reduced FSH levels may affect male reproduction and replicate the association between rs10835638 and serum FSH among infertile male patients. DESIGN: Genotyping of rs10835638 in a cohort of infertile men (n = 1029; Andrology Center of the Tartu University Clinics, Estonia), including idiopathic infertility cases (IIFC; n = 750). PATIENTS: Patients included male partners (sperm concentration <20 x 10(6)/ml) of infertile couples failing to conceive a child for 12 months or longer. RESULTS: A significant excess of TT homozygotes (1.1 vs. 2.4%) as well as GT heterozygotes (22.4 vs. 25.1%) was detected among infertile men compared with the young male cohort (chi(2) test, P < 0.05). The T allele of rs10835638 was associated with reduced serum FSH (analysis of covariance; full cohort: P = 1.20 x 10(-6), F = 13.8; IIFC: P = 7.70 x 10(-7), F = 14.3) as well as with low FSH to LH ratio (full cohort: P = 1.52 x 10(-11), F = 25.6; IIFC: P = 3.25 x 10(-9), F = 20.4). The median serum FSH levels differed between the GG and TT carriers by 48.5%. All IIFC with TT genotype exhibited low (<1.8) FSH to LH ratio. CONCLUSIONS: In perspective, this genetic marker may have clinical significance in molecular diagnostics of male reproductive success and a potential to identify positive responders to FSH treatment.