New developments and future trajectories in supernumerary sex chromosome abnormalities: a summary of the 2022 3rd International Workshop on Klinefelter Syndrome, Trisomy X, and XYY

The 3rd International Workshop on Klinefelter Syndrome, Trisomy X, and 47,XYY syndrome was held in Leiden, the Netherlands, on September 12-14, 2022. Here, we review new data presented at the workshop and discuss scientific and clinical trajectories. We focus on shortcomings in knowledge and therefore point out future areas for research. We focus on the genetics and genomics of supernumerary sex chromosome syndromes with new data being presented. Most knowledge centre specifically on Klinefelter syndrome, where aspects on testosterone deficiency and the relation to bone, muscle and fat were discussed, as was infertility and the treatment thereof. Both trisomy X and 47,XYY syndrome are frequently affected by infertility. Transitioning of males with Klinefelter syndrome was addressed, as this seemingly simple process in practise is often difficult. It is now realized that neurocognitive changes are pervasive in all supernumerary sex chromosome syndromes, which were extensively discussed. New intervention projects were also described, and exciting new data concerning these were presented. Advocacy organizations were present, describing the enormous burden carried by parents when having to explain their child's specific syndrome to most professionals whenever in contact with health care and education systems. It was also pointed out that most countries do not have health care systems that diagnose patients with supernumerary sex chromosome syndromes, thus pinpointing a clear deficiency in the current genetic testing and care models. At the end of the workshop, a roadmap towards the development of new international clinical care guidelines for Klinefelter syndrome was decided.

O-248 Cluster Analysis of men with idiopathic and unexplained male infertility identifies FSHB Genotype as relevant diagnostic parameter

Study question

In a cohort of idiopathic and unexplained infertile men we aimed to identify subgroups with similar characteristics, and therewith underlying etiologic factors, by clustering approach.

Summary answer

We identified two distinct patient clusters. Across all diverse phenotypes of infertility, the strongest segregation markers were FSHB c.-211G>T, FSH, and bi-testicular volume.

What is known already

In about 30-75% of infertile men no major causative factors can be identified; leading to the diagnose of unexplained (normozoospermia) or idiopathic (abnormal semen parameters) male infertility. This cohort of men remains very heterogenous, albeit the detailed andrological characterization that is currently applied in infertility workup.

New analysis tools such as machine learning and cluster analysis can provide a more in-depth approach. Such explorative analyses have the potential to uncover hitherto hidden patterns in data that might be difficult to spot for andrologists but become visible by these tools.

Study design, size, duration

A Cluster analysis was retrospectively performed in a clinically well characterized cohort of 2742 men with unexplained or idiopathic male infertility. These men had visited our Centre within a 10-year period (2008-2018) for infertility workup. Due to the well curated database (Androbase®) we were able to include up to 37 andrologic parameters in the unbiased cluster analysis.

Participants/materials, setting, methods

After applying strict selection criteria 2742, of initially 7627, infertile men remained for cluster analysis (exclusion: obstructive -, genetic -, other causative factors, female factor; inclusion: azoo- to normozoospermia, FSH ≥ 1IU/l, Testosterone ≥ 8nmol/l). For subsequent analyses the following parameters were included: somatic/semen/hormone parameters, testicular sonography and testis volume, genotyping of the FSHB c.-211G>T (rs10835638) single nucleotide polymorphism. For cluster analysis, partitioning around medoids method was employed based on Gower distance between patients.

Main results and the role of chance

The applied cluster approach for the study population yielded two separate clusters (average silhouette width ∼0.12). These clusters showed significantly different distributions in bi-testicular volume, FSH and FSHB genotype. Cluster 1 contained all men homozygous for G (wildtype) in FSHB c.-211G>T (100%), while Cluster 2 contained most patients carrying a T allele (>96.6%). Even in subgroup analysis (Total sperm count (TSC) <1Mill and TSC 1³Mill) two clusters each were formed too. Again, the strongest segregation markers between the respective clusters were FSHB c.-211G>T, bitesticular volume, and FSH, supporting the notion of a contributing genetic factor.

Surprisingly, sperm parameters like TSC, motility and morphology played a minor role in cluster formation; as well as testicular maldescent, varicocele, smoking, and microlithiasis testes.

The genetic parameter of FSHB c.-211G>T in combination with the established parameters FSH and testicular volume should attract more attention in future clinical workups of infertile men with unknown etiologic factors.

Limitations, reasons for caution

Categorical and numeric features contribute diversely to the calculation of patient dissimilarity. Potentially, categorical features can have a higher impact because patients are rated as completely different if they fall in different categories; for numeric features, the dissimilarity depends on the range of values.

Wider implications of the findings

The FSHB SNP was identified as an informative segregation marker; we therefore suggest introducing diagnostic genotyping into clinical routine in men with so far idiopathic or unexplained male infertility. This may reduce the high number of infertile men with so far unknown origin by nearly one-third.

Trial registration number

DFG Clinical Research Unit 326 Male Germ Cells

FSHB Genotype Identified as a Relevant Diagnostic Parameter Revealed by Cluster Analysis of Men With Idiopathic Infertility

Introduction and Objectives

About 30-75% of infertile men are diagnosed with idiopathic infertility, thereby lacking major causative factors to explain their impaired fertility status. In this study, we used a large cohort of idiopathic infertile men to determine whether subgroups could be identified by an unbiased clustering approach and whether underlying etiologic factors could be delineated.

Patients and Methods

From our in-house database Androbase®, we retrospectively selected patients (from 2008 to 2018) with idiopathic male infertility (azoo- to normozoospermia) who fit the following selection criteria: FSH ≥ 1 IU/l, testosterone ≥ 8 nmol/l, ejaculate volume ≥ 1.5 ml. Patients with genetic abnormalities or partners with female factors were excluded.For the identified study population (n=2742), we used common andrologic features (somatic, semen and hormonal parameters, including the FSHB c.-211G>T (rs10835638) single nucleotide polymorphism) for subsequent analyses. Cluster analyses were performed for the entire study population and for two sub-cohorts, which were separated by total sperm count (TSC) thresholds: Cohort A (TSC ≥ 1 mill/ejac; n=2422) and Cohort B (TSC < 1 mill/ejac; n=320). For clustering, the partitioning around medoids method was employed, and the quality was evaluated by average silhouette width.

Results

The applied cluster approach for the whole study population yielded two separate clusters, which showed significantly different distributions in bi-testicular volume, FSH and FSHB genotype. Cluster 1 contained all men homozygous for G (wildtype) in FSHB c.-211G>T (100%), while Cluster 2 contained most patients carrying a T allele (>96.6%). In the analyses of sub-cohorts A/B, two clusters each were formed too. Again, the strongest segregation markers between the respective clusters were bi-testicular volume, FSH and FSHB c.-211G>T.

Conclusion

With this first unbiased approach for revealing putative subgroups within a heterogenous group of idiopathic infertile men, we did indeed identify distinct patient clusters. Surprisingly, across all diverse phenotypes of infertility, the strongest segregation markers were FSHB c.-211G>T, FSH, and bi-testicular volume. Further, Cohorts A and B were significantly separated by FSHB genotype (wildtype vs. T-allele carriers), which supports the notion of a contributing genetic factor. Consequently, FSHB genotyping should be implemented as diagnostic routine in patients with idiopathic infertility.

O-089 A Genome Wide Association Study in men with unexplained infertility identifies nine SNPs at the FSHB locus to be associated with Follicle Stimulating Hormone level

Study question

Which single nucleotide polymorphisms (SNPs) are associated with Follicle stimulating hormone (FSH) levels in men with unexplained infertility and can affect FSH action and spermatogenesis?

Summary answer

We identified a genomic region at chromosome 11p.14.1, including nine SNPs, that are significantly associated with FSH levels in men with unexplained infertility.

What is known already

FSH action is essential for the initiation and maintenance of human spermatogenesis. One well-studied SNP, FSHB c.-211G&gt;T (rs10835638), is associated with FSHB mRNA transcription and directly affects FSH serum levels, testicular volume and spermatogenesis. Carriers of a T-allele in this promoter are diagnosed with functional secondary hypogonadism with isolated FSH deficiency.

Other genetic variants, for example at the FSHR have been shown to slightly modulate FSH action, however the clinical impact in these variants seems to

be low. The so far identified FSH-associated SNPs revealed an impact of up to 2.3 % on FSH serum level variance.

Study design, size, duration

A Genome wide association study (GWAS) was performed on a clinically well characterized cohort of 742 men with unexplained infertility (discovery study). Of the nine identified SNPs, validation was performed for rs11031005 and the already described rs10835638 in an independent cohort of 1123 men with unexplained infertility (validation study).

Participants/materials, setting, methods

Patients were retrospectively selected from our CeRA database Androbase® applying strict selection criteria; DNA was isolated from stored EDTA-blood samples. Informative genetic variants were identified using Illumina PsychArray v1.3. Illumina®GenomeStudio v2.0, PLINK v1.90 and R 3.6.3 were used to perform quantitative association analysis based on normalized FSH values. The validation study was performed using TaqMan PCR for SNP detection and R 3.6.3 for quantitative association to analyze the impact of each SNP on FSH level.

Main results and the role of chance

Imputation of the GWAS data revealed 94 SNPs with suggestive significance (p &lt; 8.56e-06) and nine SNPs (including rs10835638) with genome-wide significance (p &lt; 4.28e-07). The nine SNPs are all located at the FSHB locus on Chromosome 11p.14.1 and are in high linkage disequilibrium (LD). The validation study of 1123 patients with unexplained infertility for the SNPs rs11003005 and rs10835638 revealed a significant association with FSH (p = 4.71e-06 and p = 5.55e-07) and FSH/LH ratio (p = 2.08e-12 and p = 6.4e-12).The nine significant SNPs accounted for 3.60 –4.65 % variance in FSH serum level each in the entire discovery cohort. In an oligozoospermic subgroup (n = 249) this effect was increased to 4.89 – 6.95 %.

This the first GWAS in men with unexplained infertility. This study shows that not one single SNP, but rather a genomic region has an impact on FSH serum level in men with unexplained male infertility. This effect is even more pronounced in the more severe phenotype of oligozoospermic men.

Limitations, reasons for caution

The study is restricted to men with unexplained infertility, which might cause a selection bias. Validation and functional evaluation of the eight newly identified SNPs in independent cohorts would emphasize the results more. The sample size of 742 limits detection of loci with smaller effect on FSH levels.

Wider implications of the findings

The determination of one of the nine SNPs can improve diagnostic precision in identifying men with secondary functional hypogonadism with isolated FSH deficiency. An oligozoospermic subgroup of these men would putatively benefit from FSH treatment and has to be proven in randomized controlled trials.

Trial registration number

German Research Foundation CRU326

O-118 New insight into the genetic contribution of common variants to the development of extreme phenotypes of unexplained male infertility: a multicenter genome-wide association study

Study question

What is the contribution of the common genetic variation to the development of unexplained male infertility due to severe spermatogenic failure (SPGF)?

Summary answer

Genetic polymorphisms of key immune and spermatogenesis loci are involved in the etiology of the most severe SPGF cases, defined by Sertoli cell-only (SCO) phenotype.

What is known already

Male infertility is a rising worldwide concern that affects millions of couples. Non-obstructive azoospermia (NOA) and severe oligospermia (SO) are two extreme manifestations characterized by SPGF. A genetic cause can be established in only around 20% of affected men, with the remaining cases being classified as otherwise unexplained. To date, the genome-wide association study (GWAS) strategy, although already successfully applied in several other complex traits and diseases, was less fruitful in studies that attempted to decipher the genetic component of unexplained SPGF, mainly due to both a lack of well-powered samples in different ancestries and limitations in study design.

Study design, size, duration

We designed a GWAS for unexplained male infertility due to SPGF including a total of 1,274 affected cases and 1,951 fertile controls from the Iberian Peninsula (Spain and Portugal) and Germany. Different biostatistics and bioinformatics approaches were used to evaluate the possible effect of single-nucleotide polymorphisms (SNPs) across the whole genome in the susceptibility to specific subtypes of unexplained SPGF.

Participants/materials, setting, methods

The case cohort comprised 502 SO and 772 NOA patients, who were subdivided according to histological phenotypes (SCO, maturation arrest, and hypospermatogenesis) and the outcome of testicular sperm extraction techniques (TESE) from testis biopsies. Genotyping was performed with the GSA platform (Illumina). After quality-control and genotype imputation, 6,539,982 SNPs remained for the analysis, which was performed by logistic regression models. The datasets went through a meta-analysis by the inverse variance weighted method under fixed effects.

Main results and the role of chance

Genetic associations with SCO at the genome-wide-level of significance were identified in the major histocompatibility (MHC) class II region (rs1136759, OR = 1.80, P = 1.32E-08) and in a regulatory region of chromosome 14 nearby the vaccinia-related kinase 1 (VRK1) gene (rs115054029, OR = 3.14, P = 4.37-08). VRK1 is a relevant proliferative factor for spermatogenesis that causes progressive loss of spermatogonia when disrupted in mouse models. The role of the MHC system in SCO susceptibility was comprehensively evaluated through a validated imputation method that infers classical MHC alleles and polymorphic amino acid positions. A serine at position 13 of the HLA-DRβ1 protein (defined by the risk allele of the lead variant rs1136759) explained most of the SCO association signals within the MHC class II region. This residue is located in the binding pocket of the HLA-DR molecule and interacts directly with the presented antigen. Interestingly, position 13 of HLA-DRβ1 is the most relevant risk amino acid position for a wide spectrum of immune-mediated disorders. The HLA-DRB1*13 haplotype (which includes the serine at position 13 and represents the strongest NOA-associated marker in Asians to date) was the strongest signal amongst the classical MHC alleles in our study cohort (OR = 1.93, P = 9.90E-07).

Limitations, reasons for caution

Although the statistical power for the overall analysis was appropriate, the subphenotype analyses performed had considerably lower counts, which may influence the identification of genetic variants conferring low to moderate risk effects. Independent studies in larger SCO study cohorts should be performed to confirm our findings.

Wider implications of the findings

The molecular mechanisms underlying unexplained SPGF are largely unknown. Our data suggest a relevant role of common genetic variation in the development of SCO, the most extreme histological phenotype of NOA. SCO is characterized by the loss of germ cells and, therefore, implies a considerably higher probability of unsuccessful TESE.

Trial registration number

N/A

Ageing in men with normal spermatogenesis alters spermatogonial dynamics and nuclear morphology in Sertoli cells

BACKGROUND

Ageing in men is believed to be associated with fertility decline and elevated risk of congenital disorders for the offspring. The previous studies also reported reduced germ and Sertoli cell numbers in older men. However, it is not clear whether ageing in men with normal spermatogenesis affects the testis and germ cell population dynamics in a way sufficient for transmitting adverse age effects to the offspring.

OBJECTIVES

We examined men with normal spermatogenesis at different ages concerning effects on persisting testicular cell types, that is the germ line and Sertoli cells, as these cell populations are prone to be exposed to age effects.

MATERIAL AND METHODS

Ageing was assessed in testicular biopsies of 32 patients assigned to three age groups: (i) 28.8 ± 2.7 years; (ii) 48.1 ± 1 years; and (iii) 70.9 ± 6.2 years, n = 8 each, with normal spermatogenesis according to the Bergmann-Kliesch score, and in a group of meiotic arrest patients (29.9 ± 3.8 years, n = 8) to decipher potential links between different germ cell types. Besides morphometry of seminiferous tubules and Sertoli cell nuclei, we investigated spermatogenic output/efficiency, and dynamics of spermatogonial populations via immunohistochemistry for MAGE A4, PCNA, CREM and quantified A-pale/A-dark spermatogonia.

RESULTS

We found a constant spermatogenic output (CREM-positive round spermatids) in all age groups studied. In men beyond their mid-40s (group 2), we detected increased nuclear and nucleolar size in Sertoli cells, indirectly indicating an elevated protein turnover. From the 7th decade (group 3) of life onwards, testes showed increased proliferation of undifferentiated spermatogonia, decreased spermatogenic efficiency and elevated numbers of proliferating A-dark spermatogonia.

DISCUSSION AND CONCLUSION

Maintaining normal sperm output seems to be an intrinsic determinant of spermatogenesis. Ageing appears to affect this output and might provoke compensatory proliferation increase in A spermatogonia which, in turn, might hamper germ cell integrity.

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

Background

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

Methods

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

Results

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

Conclusion

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

[Social freezing - the male perspective]

BACKGROUND

In Germany there is an emerging trend for postponing parenthood due to non-medical, sociocultural reasons. This clearly impacts on the reproductive success due to an age-dependent decrease in fertility. Thus, strategies and techniques are currently discussed which could preserve the female fertility status, among which social freezing (cryopreservation of oocytes) for later fertilization is the most realistic one; however, while there is an intensive discussion on the procedure and timing of oocyte cryopreservation, virtually no attention has been paid to the male side and the aging effects on the male germ cells.

AIM

To evaluate the risk paternal age poses for the integrity of germ cells.

METHODS

For this review a literature search using PubMed, data from the Federal Statistical Office of Germany, the German in vitro fertilization (IVF) register as well as own data were used.

RESULTS

Sperm cell integrity is clearly affected by age both at the genetic as well as at the epigenetic levels. The estimated mutation rate for spermatozoa doubles every 16.5 years. Monogenic and multifactorial diseases are strongly associated with paternal age. Men aged >40 years have an increased risk of passing age-related mutations to their children.

CONCLUSIONS

Cryopreservation of spermatozoa is an option for men who postpone planning a family. Genetic counseling is recommended for couples undertaking social freezing and a male age of >40 years.

An alternative interpretation of cellular 'selfish spermatogonial selection'-clusters in the human testis indicates the need for 3-D-analyses

The 'selfish spermatogonial selection'- model was proposed to explain the paternal age effect (PAE) of some congenital disorders associated with point mutations in male germ cells. According to this, spermatogonia carrying pathogenic mutations gain a selection advantage over non-mutated spermatogonia which leads to an increased number of mutated spermatogonia and consequently spermatozoa over time. Recently, an immunohistochemical approach using the premeiotic marker melanoma antigen family A4 (MAGE A4) was undertaken by the Wilkie group to confirm the presence of microclones of putatively mutated spermatogonia in testes of elderly men. The objective of our study was the age-dependent assessment of testes from men with normal spermatogenesis using MAGE A4 immunohistochemistry to identify and corroborate cellular clusters indicative for 'selfish spermatogonial selection' in our cohort. We analyzed testicular tissues obtained from men with normal spermatogenesis assigned to three age groups [(1) 28.8 ± 2.7 years; (2) 48.1 ± 1 years; (3) 71.9 ± 6.8 years, n/group = 8]. We could detect very similar distribution patterns of MAGE A4-positive cells and the presence of several types of microclusters as reported previously. However, these cellular clusters, indicative for clonal expansion, were not only present in testes from elderly men but also in those from age group 1 and 2. Using graphical three-dimensional modelling, we identified that cross-section directions e.g. longitudinal sections might provoke misleading interpretation of spermatogonial clusters, in particular when the tissue processing is limited. Thus, appropriate fixation and embedding is needed for reliable analysis of testicular sections. We therefore propose a more careful interpretation of such spermatogonial clusters and recommend a 3-D analysis to unequivocally determine 'selfish spermatogonial selection'-manifestations.

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.

Differences in Signal Activation by LH and hCG are Mediated by the LH/CG Receptor's Extracellular Hinge Region

The human lutropin (hLH)/choriogonadotropin (hCG) receptor (LHCGR) can be activated by binding two slightly different gonadotropic glycoprotein hormones, choriogonadotropin (CG) - secreted by the placenta, and lutropin (LH) - produced by the pituitary. They induce different signaling profiles at the LHCGR. This cannot be explained by binding to the receptor's leucine-rich-repeat domain (LRRD), as this binding is similar for the two hormones. We therefore speculate that there are previously unknown differences in the hormone/receptor interaction at the extracellular hinge region, which might help to understand functional differences between the two hormones. We have therefore performed a detailed study of the binding and action of LH and CG at the LHCGR hinge region. We focused on a primate-specific additional exon in the hinge region, which is located between LRRD and the serpentine domain. The segment of the hinge region encoded by exon10 was previously reported to be only relevant to hLH signaling, as the exon10-deletion receptor exhibits decreased hLH signaling, but unchanged hCG signaling. We designed an advanced homology model of the hormone/LHCGR complex, followed by experimental characterization of relevant fragments in the hinge region. In addition, we examined predictions of a helical exon10-encoded conformation by block-wise polyalanine (helix supporting) mutations. These helix preserving modifications showed no effect on hormone-induced signaling. However, introduction of a structure-disturbing double-proline mutant LHCGR-Q303P/E305P within the exon10-helix has, in contrast to exon10-deletion, no impact on hLH, but only on hCG signaling. This opposite effect on signaling by hLH and hCG can be explained by distinct sites of hormone interaction in the hinge region. In conclusion, our analysis provides details of the differences between hLH- and hCG-induced signaling that are mainly determined in the L2-beta loop of the hormones and in the hinge region of the receptor.

Intratesticular testosterone is increased in men with Klinefelter syndrome and may not be released into the bloodstream owing to altered testicular vascularization– a preliminary report

Klinefelter syndrome (KS, 47,XXY) is associated with low serum testosterone (T), long thought to arise from disturbed steroidogenesis in Leydig cells. However, intratesticular testosterone (ITT) concentrations were recently found to be normal in a KS mouse model(41,XXY*). So far, nothing was known about ITT concentrations in human patients with KS. Therefore, ITT, sex hormone-binding globulin (SHBG) and histological parameters were measured in human testicular biopsies of 11 KS patients, 30 azoospermic patients with Sertoli-cell-only syndrome and nine men with normal spermatogenesis as controls. ITT concentrations showed an overall pronounced excess over intratesticular SHBG in molar terms and were significantly increased in men with KS despite of reduced serum T levels. While the ratio of ITT/serum T was markedly increased in KS, the ITT/LH-ratio was comparable between all groups. After finding significantly increased ITT levels in men with KS, a finding even more striking than in the 41,XXY* KS mouse model, we set out to find a possible 'vascular' explanation for the lack of T release into the testicular blood stream. In testis biopsies from patients,reliable analysis of the vessels is, however, not possible because of the bias resulting from the dissection technique requiring avoidance of larger blood vessels to prevent bleeding. Consequently, the blood vessel constitution was evaluated in whole testis sections from adult male 41,XXY* and 40,XY*mice (n=5, each). Indeed, the blood vessel/testes surface ratio correcting for the smaller testes of XXY*mice was significantly lower in these mice compared with XY*controls. In conclusion, testicular T production does not seem to be impaired in men with KS. On the contrary, ITT concentrations are increased, but not because of increased SHBG activity. The data from the mouse model let us speculate that a reduced vascular bed might be involved in lower release of T into the blood stream.

MicroRNA miR-513a-3p acts as a co-regulator of luteinizing hormone/chorionic gonadotropin receptor gene expression in human granulosa cells

The luteinizing hormone/chorionic gonadotropin receptor (LHCGR) is essential for normal male and female reproductive processes. The spatial and temporal LHCGR gene expression is controlled by a complex system of regulatory mechanisms which are crucial for normal physiological function, especially during the female cycle. In this study, we aimed to elucidate whether microRNAs are involved in this network and play a role in regulating LHCGR expression. Computational analysis predicted that miR-513a-3p interacts with the LHCGR mRNA via three binding sites located in the 3'UTR region, enabling a synergistic action. Moreover, using a luciferase-based reporter assay we found that miR-513a-3p targets the LHCGR, resulting in a significant down-regulation of its expression. In human primary granulosa cell cultures we detected a dynamic, inversely associated expression pattern of miR-513a-3p and the LHCGR. In addition, transfection with miR-513a-3p or its specific inhibitor led to a down- or up-regulation at the LHCGR mRNA level, respectively. An increased amount of miR-513a-3p resulted in the down-regulation of the LHCGR mRNA, reflected by the attenuation of cAMP synthesis after hormonal stimulation. In conclusion, these data demonstrate that miR-513a-3p is involved in the control of the LHCGR expression by an inversely regulated mechanism at the post-transcriptional level and show for the first time that this kind of post-transcriptional process contributes to the multifaceted system of the human LHCGR regulation.

DNA methylation in spermatozoa as a prospective marker in andrology

Recent studies have shown associations of aberrant DNA methylation in spermatozoa with idiopathic infertility. The analysis of DNA methylation of specific genes could therefore serve as a valuable diagnostic marker in clinical andrology. For this purpose, rapid and reliable detection methods, reference values and the temporal stability of spermatozoal DNA methylation need to be established and demonstrated. In this prospective study, swim-up purified semen samples from 212 consecutive patients (single samples), 31 normozoospermic volunteers (single samples) and 10 normozoospermic volunteers (four samples at days 1, 3, 42 and 45 plus a fifth sample after 180-951 days) were collected. Spermatozoal DNA was isolated, bisulphite converted and DNA methylation was analysed by pyrosequencing. DNA methylation of the maternally imprinted gene MEST was measured in samples of 212 patients and 31 normozoospermic volunteers and the temporal stability of eight different genes and two repetitive elements was examined in consecutive samples of 10 normozoospermic volunteers. MEST DNA methylation was significantly associated with oligozoospermia, decreased bi-testicular volume and increased FSH levels. A reference range for spermatozoal MEST DNA methylation (0-15%) was established using the 95th percentile of DNA methylation in normozoospermic volunteers. Using this reference range, around 23% of our patient cohort displayed an aberrant MEST DNA methylation. This epigenetic aberration was found to be significantly associated with bi-testicular volume, sperm concentration and total sperm count. DNA methylation in normozoospermic volunteers was stable over a time period of up to 951 days in contrast to classical semen parameters. Our data show that MEST DNA methylation fulfils the prerequisites to be used as routine parameter and support its use during andrological workup if a prognostic value can be shown in future.

A combined approach facilitates the reliable detection of human spermatogonia in vitro

STUDY QUESTION

Does a combined approach allow for the unequivocal detection of human germ cells and particularly of spermatogonia in vitro?

SUMMARY ANSWER

Based on our findings, we conclude that an approach comprising: (i) the detailed characterization of patients and tissue samples prior to the selection of biopsies, (ii) the use of unambiguous markers for the characterization of cultures and (iii) the use of biopsies lacking the germ cell population as a negative control is the prerequisite for the establishment of human germ cell cultures.

WHAT IS KNOWN ALREADY

The use of non-specific marker genes and the failure to assess the presence of testicular somatic cell types in germ cell cultures may have led to a misinterpretation of results and the erroneous description of germ cells in previous studies.

STUDY DESIGN, SIZE, DURATION

Testicular biopsies were selected from a pool of 264 consecutively obtained biopsies. Based on the histological diagnosis, biopsies with distinct histological phenotypes were selected (n = 35) to analyze the expression of germ cell and somatic cell markers. For germ cell culture experiments, gonadotrophin levels and clinical data were used as selection criteria resulting in the following two groups: (i) biopsies with qualitatively intact spermatogenesis (n = 4) and (ii) biopsies from Klinefelter syndrome Klinefelter patients lacking the germ cell population (n = 3).

PARTICIPANTS/MATERIALS, SETTING, METHODS

Quantitative real-time PCR analyses were performed to evaluate the specificity of 18 selected germ cell and 3 somatic marker genes. Cell specificity of individual markers was subsequently validated using immunohistochemistry. Finally, testicular cell cultures were established and were analyzed after 10 days for the expression of germ cell- (UTF1, FGFR3, MAGE A4, DDX4) and somatic cell-specific markers (SMA, VIM, LHCGR) at the RNA and the protein levels.

MAIN RESULTS AND THE ROLE OF CHANCE

Interestingly, only 9 out of 18 marker genes reflected the presence of germ cells and cell specificity could be validated using immunohistochemistry. Furthermore, VIM, SMA and LHCGR were found to reflect the presence of testicular somatic cells at the RNA and the protein levels. Using this validated marker panel and biopsies lacking the germ cell population (n = 3) as a negative control, we demonstrated that germ cell cultures containing spermatogonia can be established from biopsies with normal spermatogenesis (n = 4) and that these cultures can be maintained for the period of 10 days. However, marker profiling has to be performed at regular time points as the composition of testicular cell types may continuously change under longer term culture conditions.

LIMITATIONS, REASONS FOR CAUTION

There are significant differences regarding the spermatogonial stem cell (SSC) system and spermatogenesis between rodents and primates. It is therefore possible that marker genes that do not reflect the presence of spermatogonia in the human are specific for spermatogonia in other animal models.

WIDER IMPLICATIONS OF THE FINDINGS

While some studies have reported that human SSCs can be maintained in vitro and show characteristics of pluripotency, the germ cell origin and the differentiation potential of these cells were subsequently called into question. This study provides critical insights into possible sources for the misinterpretation of results regarding the presence of germ cells in human testicular cell cultures and our findings can therefore help to avoid conflicting reports in the future.

STUDY FUNDING/COMPETING INTEREST(S)

This project was supported by the Stem Cell Network North Rhine-Westphalia and the Innovative Medical Research of the University of Münster Medical School (Grant KO111014). In addition, it was funded by the DFG-Research Unit FOR 1041 Germ Cell Potential (GR 1547/11-1 and SCHL 394/11-2), the BMBF (01GN0809/10) and the IZKF (CRA 03/09). The authors declare that there is no conflict of interest.

TRIAL REGISTRATION NUMBER

Not applicable.

Broad DNA methylation changes of spermatogenesis, inflammation and immune response-related genes in a subgroup of sperm samples for assisted reproduction

Aberrant sperm DNA methylation patterns, mainly in imprinted genes, have been associated with male subfertility and oligospermia. Here, we performed a genome-wide methylation analysis in sperm samples representing a wide range of semen parameters. Sperm DNA samples of 38 males attending a fertility centre were analysed with Illumina HumanMethylation27 BeadChips, which quantify methylation of >27 000 CpG sites in cis-regulatory regions of almost 15 000 genes. In an unsupervised analysis of methylation of all analysed sites, the patient samples clustered into a major and a minor group. The major group clustered with samples from normozoospermic healthy volunteers and, thus, may more closely resemble the normal situation. When correlating the clusters with semen and clinical parameters, the sperm counts were significantly different between groups with the minor group exhibiting sperm counts in the low normal range. A linear model identified almost 3000 CpGs with significant methylation differences between groups. Functional analysis revealed a broad gain of methylation in spermatogenesis-related genes and a loss of methylation in inflammation- and immune response-related genes. Quantitative bisulfite pyrosequencing validated differential methylation in three of five significant candidate genes on the array. Collectively, we identified a subgroup of sperm samples for assisted reproduction with sperm counts in the low normal range and broad methylation changes (affecting approximately 10% of analysed CpG sites) in specific pathways, most importantly spermatogenesis-related genes. We propose that epigenetic analysis can supplement traditional semen parameters and has the potential to provide new insights into the aetiology of male subfertility.

The RHOX homeobox gene cluster is selectively expressed in human oocytes and male germ cells

STUDY QUESTION

What human tissues and cell types express the X-linked reproductive homeobox (RHOX) gene cluster?

SUMMARY ANSWER

The RHOX homeobox genes and proteins are selectively expressed in germ cells in both the ovary and testis.

WHAT IS KNOWN ALREADY

The RHOX homeobox transcription factors are encoded by an X-linked gene cluster whose members are selectively expressed in the male and female reproductive tract of mice and rats. The Rhox genes have undergone strong selection pressure to rapidly evolve, making it uncertain whether they maintain their reproductive tissue-centric expression pattern in humans, an issue we address in this report.

STUDY DESIGN, SIZE, DURATION

We examined the expression of all members of the human RHOX gene cluster in 11 fetal and 8 adult tissues. The focus of our analysis was on fetal testes, where we evaluated 16 different samples from 8 to 20 weeks gestation. We also analyzed fixed sections from fetal testes, adult testes and adult ovaries to determine the cell type-specific expression pattern of the proteins encoded by RHOX genes.

PARTICIPANTS/MATERIALS, SETTING, METHODS

We used quantitative reverse transcription-polymerase chain reaction analysis to assay human RHOX gene expression. We generated antisera against RHOX proteins and used them for western blotting, immunohistochemical and immunofluorescence analyses of RHOXF1 and RHOXF2/2B protein expression.

MAIN RESULTS AND THE ROLE OF CHANCE

We found that the RHOXF1 and RHOXF2/2B genes are highly expressed in the testis and exhibit low or undetectable expression in most other organs. Using RHOXF1- and RHOXF2/2B-specific antiserum, we found that both RHOXF1 and RHOXF2/2B are primarily expressed in germ cells in the adult testis. Early stage germ cells (spermatogonia and early spermatocytes) express RHOXF2/2B, while later stage germ cells (pachytene spermatocytes and round spermatids) express RHOXF1. Both RHOXF1 and RHOXF2/2B are expressed in prespermatogonia in human fetal testes. Consistent with this, RHOXF1 and RHOXF2/2B mRNA expression increases in the second trimester during fetal testes development when gonocytes differentiate into prespermatogonia. In the human adult ovary, we found that RHOXF1 and RHOXF2/2B are primarily expressed in oocytes.

LIMITATIONS, REASONS FOR CAUTION

While the average level of expression of RHOX genes was low or undetectable in all 19 human tissues other than testes, it is still possible that RHOX genes are highly expressed in a small subset of cells in some of these non-testicular tissues. As a case in point, we found that RHOX proteins are highly expressed in oocytes within the human ovary, despite low levels of RHOX mRNA in the whole ovary.

WIDER IMPLICATIONS OF THE FINDINGS

The cell type-specific and developmentally regulated expression pattern of the RHOX transcription factors suggests that they perform regulatory functions during human fetal germ cell development, spermatogenesis and oogenesis. Our results also raise the possibility that modulation of RHOX gene levels could correct some cases of human infertility and that their encoded proteins are candidate targets for contraceptive drug design.

The pluripotency factor LIN28 in monkey and human testes: a marker for spermatogonial stem cells?

Mammalian spermatogenesis is maintained by spermatogonial stem cells (SSCs). However, since evidentiary assays and unequivocal markers are still missing in non-human primates (NHPs) and man, the identity of primate SSCs is unknown. In contrast, in mice, germ cell transplantation studies have functionally demonstrated the presence of SSCs. LIN28 is an RNA-binding pluripotent stem cell factor, which is also strongly expressed in undifferentiated mouse spermatogonia. By contrast, two recent reports indicated that LIN28 is completely absent from adult human testes. Here, we analyzed LIN28 expression in marmoset monkey (Callithrix jacchus) and human testes during development and adulthood and compared it with that in mice. In the marmoset, LIN28 was strongly expressed in migratory primordial germ cells and gonocytes. Strikingly, we found a rare LIN28-positive subpopulation of spermatogonia also in adult marmoset testis. This was corroborated by western blotting and quantitative RT–PCR. Importantly, in contrast to previous publications, we found LIN28-positive spermatogonia also in normal adult human and additional adult NHP testes. Some seasonal breeders exhibit a degenerated (involuted) germinal epithelium consisting only of Sertoli cells and SSCs during their non-breeding season. The latter re-initiate spermatogenesis prior to the next breeding-season. Fully involuted testes from a seasonal hamster and NHP (Lemur catta) exhibited numerous LIN28-positive spermatogonia, indicating an SSC identity of the labeled cells. We conclude that LIN28 is differentially expressed in mouse and NHP spermatogonia and might be a marker for a rare SSC population in NHPs and man. Further characterization of the LIN28-positive population is required.

Developmental expression of the pluripotency factor sal-like protein 4 in the monkey, human and mouse testis: restriction to premeiotic germ cells

SALL4 (sal-like protein 4) is a pluripotency transcription factor, which is highly expressed in embryonic stem (ES) cells and which is essential for mouse preimplantation development. In adult mouse organs, Sall4 mRNA is highly expressed in the testis and ovary, while there is only little or no expression in other organs. There is also a high expression of SALL4 in human testicular germ cell tumors. However, there is as yet no detailed analysis of SALL4 expression during mammalian testicular development. We analyzed SALL4 expression in ES cells, preimplantation embryos, and the developing and adult testis of a nonhuman primate (NHP) species, the common marmoset monkey (Callithrix jacchus). Immunofluorescence revealed SALL4 in the nuclei of marmoset ES cells and preimplantation embryos. Marmoset SALL4 isoform analysis in ES cells and newborn and adult testis by RT- PCR and Western blotting showed two different isoforms, SALL4-A and SALL4-B. Immunohistochemistry localized this transcription factor to the nuclei of primordial germ cells and most gonocytes in the prenatal and early postnatal marmoset testis. In the pubertal and adult testis SALL4 was present in undifferentiated spermatogonia. In the developing and adult human and mouse testis SALL4 expression mimicked the pattern in the marmoset. Adult testes from additional NHP species, the treeshrew, the cat and the dog also exhibited SALL4 in undifferentiated spermatogonia, indicating a conserved expression in the mammalian testis. Taking into account the importance of SALL4 for mouse development, we conclude that SALL4 may play an important role during mammalian germ cell development and is involved in the regulation of spermatogonial proliferation in the adult testis.

Misleading and reliable markers to differentiate between primate testis-derived multipotent stromal cells and spermatogonia in culture

BACKGROUND

Several studies have reported the generation of spermatogonia-derived pluripotent stem cells from human testes. The initial aim of the present study was the derivation of equivalent stem cells from an established and experimentally accessible non-human primate model, the common marmoset monkey (Callithrix jacchus). However, an essential prerequisite in the absence of transgenic reporters in primates and man is the availability of validated endogenous markers for the identification of specific cell types in vitro.

METHODS AND RESULTS

We cultured marmoset testicular cells in a similar way to that described for human testis-derived pluripotent cells and set out to characterize these cultures under different conditions and in differentiation assays applying established marker panels. Importantly, the cells emerged as testicular multipotent stromal cells (TMSCs) instead of (pluripotent) germ cell-derived cells. TMSCs expressed many markers such as GFR-α, GPR125, THY-1 (CD90), ITGA6, SSEA4 and TRA-1-81, which were considered as spermatogonia specific and were previously used for the enrichment or characterization of spermatogonia. Proliferation of TMSCs was highly dependent on basic fibroblast growth factor, a growth factor routinely present in germ cell culture media. As reliable markers for the distinction between spermatogonia and TMSCs, we established VASA, in combination with the spermatogonia-expressed factors, MAGEA4, PLZF and SALL4.

CONCLUSIONS

Marmoset monkey TMSCs and spermatogonia exhibit an overlap of markers, which may cause erroneous interpretations of experiments with testis-derived stem cells in vitro. We provide a marker panel for the unequivocal identification of spermatogonia providing a better basis for future studies on primate, including human, testis-derived stem cells.

Role of the CAG repeat polymorphism of the androgen receptor gene in polycystic ovary syndrome (PCOS)

BACKGROUND

Polycystic ovary syndrome (PCOS) is a frequent heterogenic disorder with a familial background. Androgenic effects, determining the clinical features of the syndrome, are mediated by the androgen receptor (AR), whose activity is modulated by a genetic polymorphism. We investigated the role of the CAG repeat polymorphism of the androgen receptor in PCOS.

METHODS

In the infertility unit of a university clinic, 72 PCOS patients were compared with 179 ovulatory controls undergoing a standardized diagnostic work-up. The number of CAG repeats was determined by PCR, labelling with IR-800 and PAGE. X-chromosome inactivation was assessed by a methylation-sensitive assay.

RESULTS

Compared to controls, PCOS patients displayed a shorter mean CAG repeat length, encoding for higher AR activity (P=0.001). CAG repeat length correlated inversely with oligomenorrhea, a central androgen dependent feature of the syndrome (P=0.005). In a binomial regression analysis including BMI, LH and free testosterone, CAG repeat length was identified as an independent risk factor for PCOS (P=0.002).

CONCLUSIONS

The CAG repeat polymorphism could constitute one of the genetic factors modulating the syndrome's phenotype, contributing to its clinical heterogeneity and associated metabolic consequences.

Variation in CAG and GGN repeat lengths and CAG/GGN haplotype in androgen receptor gene polymorphism and prostate carcinoma in Nigerians

Prostate cancer has become the most common cancer in Nigerian men. The growth of the prostate gland depends on circulating androgens and intracellular steroid signalling pathways. The effects of androgens are mediated through the androgen receptor (AR), a nuclear transcription factor encoded by the AR gene. The common polymorphisms, CAG and GGN repeats, in exon 1 of this gene have been implicated as possible risk factors. Thus far, existing supporting data are scanty and none are from sub-Saharan African populations. Therefore, this study investigates the possible association between AR polymorphism repeat length (CAG and GGN) and prostate cancer in Nigerians. A total of 261 subjects (70 with prostate cancer, 68 with benign prostate hyperplasia [BPH], 123 age-matched apparently normal subjects as controls) were studied. CAG and GGN repeats length were determined by fragment length analysis using GeneScan. The CAG repeat length in prostate cancer and in BPH compared to the controls was significantly different (P < 0.05) with reduce length of CAG repeats showing a significant odds ratio (OR) in both cases. However, this was not observed in GGN repeat length, which showed no significant difference between cases and controls (P > 0.05). CAG and GGN haplotype variation showed no significant difference between cases and controls (P > 0.05), except that the haplotypes CAG > or =21 and GGN < or =21 were more common in the control group. The results of this study, the first from sub-Saharan Africa, supports the hypothesis that reduced CAG repeat length is a risk factor for prostate cancer, and also suggests an association with BPH.

Reduced expression of DNMT3B in the germ cells of patients with bilateral spermatogenic arrest does not lead to changes in the global methylation status

DNA methylation events during spermatogenesis have important implications for gamete integrity and transmission of epigenetic information to the next generation. However, the role of DNA methyltransferases in the disorders of human spermatogenesis has not been elucidated. The aim of the present study was to evaluate the expression of DNMT3B, crucial for full germ cell methylation, in testicular germ cells of patients with spermatogenic arrest and to determine whether or not there is an association with the global methylation status. In order to determine the DNMTs expression status at various stages of spermatogenesis, immunohistochemical localization was performed on 16 fertile controls having normal spermatogenesis and 11 patients with bilateral spermatogenic arrest. DNMT3B was expressed in most of the germ cell types in both controls and patients with bilateral spermatogenic arrest. The number of DNMT3B positive preleptotene/zygotene cells and pachytene spermatocytes was significantly lower in patients with bilateral arrest. However, evaluation of 5-methylcytosine, a global methylation marker, in the few matured germ cells of these patients did not reveal altered methylation. In conclusion, the global methylation status of germ cells is not affected by spermatogenic defects in spite of aberrant DNMT3B expression indicating the necessity of proper methylation for full spermatogenesis.

Idiopathic male infertility is strongly associated with aberrant methylation of MEST and IGF2/H19 ICR1

Aberrant imprinting in spermatozoa in a subset of infertile men has been postulated to be a risk factor for congenital diseases in children conceived via assisted reproduction techniques (ART). Studies in clinically well characterized large cohorts, however, have been missing. Using bisulfite sequencing, we determined the degree of methylation of the IGF2/H19 imprinting control region 1 (ICR1) and MEST differentially methylated regions in swim-up purified spermatozoa from 148 idiopathic infertile men and 33 normozoospermic controls. All control individuals had a high degree of IGF2/H19 ICR1 and a low degree of MEST methylation. Low sperm counts were clearly associated with IGF2/H19 ICR1 hypomethylation and, even stronger, with MEST hypermethylation. MEST hypermethylation, but not IGF2/H19 ICR1 hypomethylation was found in idiopathic infertile men with progressive sperm motility below 40% and bad sperm morphology below 5% normal spermatozoa. Ageing could be ruled out as a cause for the observed methylation defects. Sequence analysis of the CTCFL gene in peripheral blood DNA from 20 men with severe methylation defects revealed several polymorphisms, but no bona fide mutation. We conclude that idiopathic male infertility is strongly associated with imprinting defects at IGF2/H19 ICR1 and MEST, with aberrant MEST methylation being a strong indicator for sperm quality. The male germ cell thus represents a potential source for aberrant epigenetic features in children conceived via ART.

Germ cell dynamics in the testis of the postnatal common marmoset monkey (Callithrix jacchus)

The seminiferous epithelium in the nonhuman primate Callithrix jacchus is similarly organized to man. This monkey has therefore been used as a preclinical model for spermatogenesis and testicular stem cell physiology. However, little is known about the developmental dynamics of germ cells in the postnatal primate testis. In this study, we analyzed testes of newborn, 8-week-old, and adult marmosets employing immunohistochemistry using pluripotent stem cell and germ cell markers DDX4 (VASA), POU5F1 (OCT3/4), and TFAP2C (AP-2γ). Stereological and morphometric techniques were applied for quantitative analysis of germ cell populations and testicular histological changes. Quantitative RT-PCR (qRT-PCR) of testicular mRNA was applied using 16 marker genes establishing the corresponding profiles during postnatal testicular development. Testis size increased during the first 8 weeks of life with the main driver being longitudinal outgrowth of seminiferous cords. The number of DDX4-positive cells per testis doubled between birth and 8 weeks of age whereas TFAP2C- and POU5F1-positive cells remained unchanged. This increase in DDX4-expressing cells indicates dynamic growth of the differentiated A-spermatogonial population. The presence of cells expressing POU5F1 and TFAP2C after 8 weeks reveals the persistence of less differentiated germ cells. The mRNA and protein profiles determined by qRT-PCR and western blot in newborn, 8-week-old, and adult marmosets corroborated the immunohistochemical findings. In conclusion, we demonstrated the presence of distinct spermatogonial subpopulations in the primate testis exhibiting different dynamics during early testicular development. Our study demonstrates the suitability of the marmoset testis as a model for human testicular development.

No correlation between androgen receptor CAG and GGN repeat length and the degree of genital virilization in females with 21-hydroxylase deficiency

CONTEXT

In 21-hydroxylase (CYP21A2) deficiency (21OHD), the level of in vitro enzymatic function allows for classification of mutation groups (null, A, B, C) and prediction of disease severity. However, genital virilization in affected females correlates only weakly with CYP21A2 mutation groups, suggesting the influence of genetic modifiers.

OBJECTIVE

The objective of the study was to investigate the influence of the polymorphic CAG and GGn repeats of the androgen receptor (AR) gene on the degree of genital virilization in 21OHD females.

DESIGN AND PATIENTS

Design of the study was the determination of CYP21A2 genotype, degree of genital virilization (Prader stage), and X-weighted biallelic mean of AR CAG and GGn repeat length in 205 females with 21OHD.

OUTCOME MEASUREMENTS

Correlation of AR CAG and GGn repeat lengths with Prader stages using nested stepwise logistic regression analysis was measured.

RESULTS

CYP21A2 mutation groups null and A showed significantly higher levels of genital virilization than groups B and C (P < 0.01). However, Prader stages varied considerably within mutation groups: null, Prader I-V (median IV); A, Prader I-V (median IV); B, Prader I-V (median III); C, 0-III (median I). Mean GGn repeat length of patients was not significantly associated with Prader stages, classified as low (0-I), intermediate (II-III), or severe (IV-V) (odds ratio per repeat: 0.98, 95% confidence interval 0.71-1.35). In contrast, patients with Prader 0-I showed a trend toward longer CAG repeats without reaching statistical significance (P = 0.07, odds ratio per repeat: 0.82, 95% confidence interval 0.65-1.02).

CONCLUSION

Neither CAG nor GGn repeat lengths are statistically significant modifiers of genital virilization in females with 21OHD.

Androgen receptor gene CAG and GGN polymorphisms in infertile Nigerian men

The human androgen receptor gene (AR) is an important regulator of male sexual development including spermatogenesis. Exon 1 of this gene encodes the N terminal domain, which controls transcriptional activity of the receptor and the two polymorphic repeats CAG and GGN. Many studies have reported association of the expanded CAG repeat length with male infertility, although this is still controversial. The GGN repeat, in contrast, has been less thoroughly studied. Thus far, only scanty studies have been reported from African populations and none from Nigeria. Therefore, we have investigated the possible association between AR polymorphism repeats length (CAG and GGN) and reduced spermatogenesis in infertile Nigerian men (no.=60) consisting of 20 non-obstructive azoospermic and 40 oligozoospermic subjects compared with controls with normozoospermia and proven evidence of fertility (no.=38). In addition, 48 volunteers with normal spermatogenesis were recruited from a German population. CAG and GGN repeats length were determined by fragment length analysis using GeneScan. The CAG and GGN repeats length of infertile compared to fertile populations were not significantly different (p>0.05). We found a unique AR GGN allele distribution with 20-23 GGN repeats predominant in the Nigerian study population. Our results show that CAG and GGN repeats polymorphisms are not a critical index of male infertility. While we do not find a relationship with CAG and GGN repeats haplotypes and male infertility, we report for the first time a unique and wider distribution of the GGN allele in the Nigerian population which is significantly different from the Caucasian population. The functional relevance of this variance to male fertility warrants in-depth elucidation.

A common haplotype of protamine 1 and 2 genes is associated with higher sperm counts

Sperm chromatin compaction in the sperm head is achieved when histones are replaced by protamines during spermatogenesis. Haploinsufficiency of the protamine 1 (PRM1) or PRM2 gene causes infertility in mice. However, the published data remain inconclusive about a role of PRM1/2 variants in male infertility and their association with semen parameters. By full sequence analysis, we assessed the frequency of sequence variations in PRM1 and PRM2 in three groups of Caucasian patients with idiopathic teratozoospermia and normal (n = 88) or reduced sperm concentration (n = 83) and in men with a high percentage of normal sperm morphology and normal concentrations (n = 77). Two rare (c.54G>A and c.102G>T) and one common SNP (c.230A>C) were identified in PRM1. In PRM2, some rare heterozygous mutations and the two common intronic SNPs 298G>C and 373C>A were detected. None of the PRM1/2 variants was associated with teratozoospermia or individually with other semen parameters. However, significant linkage disequilibrium was detected between the common SNPs of PRM1 and PRM2 which formed haplotypes. Analysis of the pooled group (n = 248) revealed that homozygous carriers of the common haplotype ACC had a twofold higher sperm concentration and count than men lacking this haplotype, with sperm counts of heterozygotes for ACC being midway between the homozygotes. This markedly decreased sperm output might either be caused by spermatozoa lacking the ACC haplotype not being viable, or subject to negative selection. In addition, a significant deviation from Hardy-Weinberg-Equilibrium of these SNPs might indicate natural selection in favour of the ACC allele which leads to higher sperm output and therefore better fertility. In conclusion, for the first time we describe an association of a common haplotype formed by PRM1 and PRM2 with sperm output in a large group of men.

Isolation and characterization of pluripotent human spermatogonial stem cell-derived cells

Several reports have documented the derivation of pluripotent cells (multipotent germline stem cells) from spermatogonial stem cells obtained from the adult mouse testis. These spermatogonia-derived stem cells express embryonic stem cell markers and differentiate to the three primary germ layers, as well as the germline. Data indicate that derivation may involve reprogramming of endogenous spermatogonia in culture. Here, we report the derivation of human multipotent germline stem cells (hMGSCs) from a testis biopsy. The cells express distinct markers of pluripotency, form embryoid bodies that contain derivatives of all three germ layers, maintain a normal XY karyotype, are hypomethylated at the H19 locus, and express high levels of telomerase. Teratoma assays indicate the presence of human cells 8 weeks post-transplantation but limited teratoma formation. Thus, these data suggest the potential to derive pluripotent cells from human testis biopsies but indicate a need for novel strategies to optimize hMGSC culture conditions and reprogramming.

[Genetics of male infertility]

Genetic causes of male infertility increase in frequency with decreasing sperm concentration (oligo-/azoospermia). The decision about genetic tests should be made after a complete andrological work-up. Common causes comprise chromosomal aberrations (including Klinefelter syndrome), microdeletions of the AZF loci of the Y chromosome, mutations in the gene responsible for cystic fibrosis (CFTR) causing CBAVD and in genes involved in hypogonadotropic hypogonadism (including Kallmann syndrome). Every genetic investigation should be accompanied by comprehensive genetic counselling to help with the interpretation of results and support the patient/the couple concerning consequences for their family planning and treatment options.

Phenotypic variation within European carriers of the Y-chromosomal gr/gr deletion is independent of Y-chromosomal background

BACKGROUND

Previous studies have compared sperm phenotypes between men with partial deletions within the AZFc region of the Y chromosome and non-carriers, with variable results. In this study, a separate question was investigated, the basis of the variation in sperm phenotype within gr/gr deletion carriers, which ranges from normozoospermia to azoospermia. Differences in the genes removed by independent gr/gr deletions, the occurrence of subsequent duplications or the presence of linked modifying variants elsewhere on the chromosome have been suggested as possible causal factors. This study set out to test these possibilities in a large sample of gr/gr deletion carriers with known phenotypes spanning the complete range.

RESULTS

In total, 169 men diagnosed with gr/gr deletions from six centres in Europe and one in Australia were studied. The DAZ and CDY1 copies retained, the presence or absence of duplications and the Y-chromosomal haplogroup were characterised. Although the study had good power to detect factors that accounted for >or=5.5% of the variation in sperm concentration, no such factor was found. A negative effect of gr/gr deletions followed by b2/b4 duplication was found within the normospermic group, which remains to be further explored in a larger study population. Finally, significant geographical differences in the frequency of different subtypes of gr/gr deletions were found, which may have relevance for the interpretation of case control studies dealing with admixed populations.

CONCLUSIONS

The phenotypic variation of gr/gr carriers in men of European origin is largely independent of the Y-chromosomal background.

Mutation analysis of the X-chromosome linked, testis-specific TAF7L gene in spermatogenic failure

The precise temporal and spatial expressions of specific transcription regulation factors (TRF) have long been considered essential for spermatogenesis. Recently, it has been speculated that mammals have evolved more specialised TRF genes. In the human, the TAF7L gene may be essential for maintenance of spermatogenesis. In this study, we investigated the possible role of the TAF7L gene located on the X chromosome in testicular function and spermatogenic failure. In a case-controlled retrospective study, we recruited 16 infertile males with consistent, nonobstructive azoospermia and with normal serum follicle-stimulating hormone (FSH) levels. Twenty age-matched men with normal spermatogenesis with the same ethnic background (Caucasian) were recruited as controls. Their genomic DNA was screened for sequence changes in the coding regions and part of the flanking introns of the TAF7L gene by direct sequencing. Amino acid sequence was compared with the NCBI standard sequence (BC043391). Semen analysis and hormone evaluation were performed. We observed six sequence variations in four patients, consisting of two point mutations, one each in exon 9 and 13 and one six-basepair deletion in exon 13 with concomitant changes in amino acid. One additional nucleotide exchange was observed in intron 8. Most of these changes were also found in eight controls with the exception of changes in exon 13. A meta-analysis including the present study and literature data suggests a possible association of the point mutation in exon 13 with infertility. There was no association or relationship with reproductive hormones. In conclusion, the sequence variants in the cDNA sequence observed are common polymorphisms. The changes in intron 8 appear novel. We report for the first time that most of the alterations are not associated with gonadal dysfunction, while the sequence variant in exon 13 may represent a risk factor for spermatogenic failure.