A genome-wide association study in Chinese men identifies three risk loci for non-obstructive azoospermia. Nat Genet. 2012;44:183-186. [PMID: 22197933 DOI: 10.1038/ng.1040]

Clinical cases series and pathogenesis of Lamb-Shaffer syndrome in China

BACKGROUND

Lamb-Shaffer syndrome (LAMSHF, OMIM: 616803) is a rare neurodevelopmental disorder characterized by global developmental delay, intellectual disability, poor expressive speech, which is attributed to haploinsufficiency by heterozygous variants of SOX5 gene (SRY-Box Transcription Factor 5, HGNC: 11201) on chromosome 12p12. A total of 113 cases have been reported in the world, however, only 3 cases have been reported.in China. Here, we aimed to report novel variants of SOX5 gene and provide examples for clinical diagnosis by reporting the clinical phenotype of a series of Chinese patients with LAMSHF.

METHODS

This study retrospectively collected the information of families of LAMSHF patients in China. Whole Exome Sequencing (WES) were performed to confirm the diagnosis of 4 children with unexplained developmental delay or epilepsy. A minigene splicing assay was used to verify whether the splice variant affected splicing. Meanwhile, a literature review was conducted to analyze the clinical and genetic characteristics of patients with LAMSHF.

RESULTS

Three of the LAMSHF patients had a de novo heterozygous mutation in the SOX5 gene respectively, c.290delC (p.Pro97fs*30), chr12:23686019_24048958del, c.1772-1C > A, and the remaining one had a mutation inherited from his father, c.1411C > T (p.Arg471*). The main clinical manifestations of these children were presented with global developmental delays, and one of them also had seizures. And the results of the minigene experiment indicated that the splice variant, c.1772-1C > A, transcribed a novel mRNA product which leaded to the formation of a truncated protein.

CONCLUSIONS

Through a comprehensive review and analysis of existing literature and this study showed intellectual disability, speech delay and facial dysmorphisms were common clinical manifestation, while the seizures and EEG abnormalities were rare (21/95, 22.16%). Notably, we represent the largest sample size of LAMSHF in Asia that encompasses previously unreported SOX5 gene mutation, and a minigene testing have been conducted to validate the pathogenicity of the c.1772-1C > A splice variant. The research further expands the phenotype and genotype of LAMSHF while offers novel insights for potential pathogenicity of genes locus.

Changes in environmental exposures over decades may influence the genetic architecture of severe spermatogenic failure

STUDY QUESTION

Do the genetic determinants of idiopathic severe spermatogenic failure (SPGF) differ between generations?

SUMMARY ANSWER

Our data support that the genetic component of idiopathic SPGF is impacted by dynamic changes in environmental exposures over decades.

WHAT IS KNOWN ALREADY

The idiopathic form of SPGF has a multifactorial etiology wherein an interaction between genetic, epigenetic, and environmental factors leads to the disease onset and progression. At the genetic level, genome-wide association studies (GWASs) allow the analysis of millions of genetic variants across the genome in a hypothesis-free manner, as a valuable tool for identifying susceptibility risk loci. However, little is known about the specific role of non-genetic factors and their influence on the genetic determinants in this type of conditions.

STUDY DESIGN, SIZE, DURATION

Case-control genetic association analyses were performed including a total of 912 SPGF cases and 1360 unaffected controls.

PARTICIPANTS/MATERIALS, SETTING, METHODS

All participants had European ancestry (Iberian and German). SPGF cases were diagnosed during the last decade either with idiopathic non-obstructive azoospermia (n = 547) or with idiopathic non-obstructive oligozoospermia (n = 365). Case-control genetic association analyses were performed by logistic regression models considering the generation as a covariate and by in silico functional characterization of the susceptibility genomic regions.

MAIN RESULTS AND THE ROLE OF CHANCE

This analysis revealed 13 novel genetic association signals with SPGF, with eight of them being independent. The observed associations were mostly explained by the interaction between each lead variant and the age-group. Additionally, we established links between these loci and diverse non-genetic factors, such as toxic or dietary habits, respiratory disorders, and autoimmune diseases, which might potentially influence the genetic architecture of idiopathic SPGF.

LARGE SCALE DATA

GWAS data are available from the authors upon reasonable request.

LIMITATIONS, REASONS FOR CAUTION

Additional independent studies involving large cohorts in ethnically diverse populations are warranted to confirm our findings.

WIDER IMPLICATIONS OF THE FINDINGS

Overall, this study proposes an innovative strategy to achieve a more precise understanding of conditions such as SPGF by considering the interactions between a variable exposome through different generations and genetic predisposition to complex diseases.

STUDY FUNDING/COMPETING INTEREST(S)

This work was supported by the "Plan Andaluz de Investigación, Desarrollo e Innovación (PAIDI 2020)" (ref. PY20_00212, P20_00583), the Spanish Ministry of Economy and Competitiveness through the Spanish National Plan for Scientific and Technical Research and Innovation (ref. PID2020-120157RB-I00 funded by MCIN/ AEI/10.13039/501100011033), and the 'Proyectos I+D+i del Programa Operativo FEDER 2020' (ref. B-CTS-584-UGR20). ToxOmics-Centre for Toxicogenomics and Human Health, Genetics, Oncology and Human Toxicology, is also partially supported by the Portuguese Foundation for Science and Technology (Projects: UIDB/00009/2020; UIDP/00009/2020). The authors declare no competing interests.

TRIAL REGISTRATION NUMBER

N/A.

Phase-separated CCER1 coordinates the histone-to-protamine transition and male fertility

Idiopathic fertility disorders are associated with mutations in various genes. Here, we report that coiled-coil glutamate-rich protein 1 (CCER1), a germline-specific and intrinsically disordered protein (IDP), mediates postmeiotic spermatid differentiation. In contrast, CCER1 deficiency results in defective sperm chromatin compaction and infertility in mice. CCER1 increases transition protein (Tnp1/2) and protamine (Prm1/2) transcription and mediates multiple histone epigenetic modifications during the histone-to-protamine (HTP) transition. Immiscible with heterochromatin in the nucleus, CCER1 self-assembles into a polymer droplet and forms a liquid-liquid phase-separated condensate in the nucleus. Notably, we identified loss-of-function (LoF) variants of human CCER1 (hCCER1) in five patients with nonobstructive azoospermia (NOA) that were absent in 2713 fertile controls. The mutants led to premature termination or frameshift in CCER1 translation, and disrupted condensates in vitro. In conclusion, we propose that nuclear CCER1 is a phase-separated condensate that links histone epigenetic modifications, HTP transitions, chromatin condensation, and male fertility.

Regulatory mechanisms of SoxD transcription factors and their influences on male fertility

Members of the SRY-related box (SOX) subfamily D (SoxD) of transcription factors are well conserved among vertebrate species and play important roles in different stages of male reproductive development. In mammals, the SoxD subfamily contains three members: SOX5, SOX6 and SOX13. Here, we describe their implications in testicular development and spermatogenesis, contributing to fertility. We also cover the mechanisms of action of SoxD transcription factors in gene regulation throughout male development. The specificity of activation of target genes by SoxD members depends, in part, on their post-translational modifications and interactions with other partners. Sperm production in adult males requires the coordination in the regulation of gene expression by different members of the SoxD subfamily of transcription factors in the testis. Specifically, the regulation of genes promoting adequate spermatogenesis by SoxD members is discussed in comparison between species.

Genome-wide assessment and mapping of inbreeding depression identifies candidate genes associated with semen traits in Holstein bulls

BACKGROUND

The reduction in phenotypic performance of a population due to mating between close relatives is called inbreeding depression. The genetic background of inbreeding depression for semen traits is poorly understood. Thus, the objectives were to estimate the effect of inbreeding and to identify genomic regions underlying inbreeding depression of semen traits including ejaculate volume (EV), sperm concentration (SC), and sperm motility (SM). The dataset comprised ~ 330 K semen records from ~ 1.5 K Holstein bulls genotyped with 50 K single nucleotide polymorphism (SNP) BeadChip. Genomic inbreeding coefficients were estimated using runs of homozygosity (i.e., F_ROH > 1 Mb) and excess of SNP homozygosity (F_SNP). The effect of inbreeding was estimated by regressing phenotypes of semen traits on inbreeding coefficients. Associated variants with inbreeding depression were also detected by regressing phenotypes on ROH state of the variants.

RESULTS

Significant inbreeding depression was observed for SC and SM (p < 0.01). A 1% increase in F_ROH reduced SM and SC by 0.28% and 0.42% of the population mean, respectively. By splitting F_ROH into different lengths, we found significant reduction in SC and SM due to longer ROH, which is indicative of more recent inbreeding. A genome-wide association study revealed two signals positioned on BTA 8 associated with inbreeding depression of SC (p < 0.00001; FDR < 0.02). Three candidate genes of GALNTL6, HMGB2, and ADAM29, located in these regions, have established and conserved connections with reproduction and/or male fertility. Moreover, six genomic regions on BTA 3, 9, 21 and 28 were associated with SM (p < 0.0001; FDR < 0.08). These genomic regions contained genes including PRMT6, SCAPER, EDC3, and LIN28B with established connections to spermatogenesis or fertility.

CONCLUSIONS

Inbreeding depression adversely affects SC and SM, with evidence that longer ROH, or more recent inbreeding, being especially detrimental. There are genomic regions associated with semen traits that seems to be especially sensitive to homozygosity, and evidence to support some from other studies. Breeding companies may wish to consider avoiding homozygosity in these regions for potential artificial insemination sires.

A novel tumor suppressor encoded by a 1p36.3 lncRNA functions as a phosphoinositide-binding protein repressing AKT phosphorylation/activation and promoting autophagy

Peptides/small proteins, encoded by noncanonical open reading frames (ORF) of previously claimed non-coding RNAs, have recently been recognized possessing important biological functions, but largely uncharacterized. 1p36 is an important tumor suppressor gene (TSG) locus frequently deleted in multiple cancers, with critical TSGs like TP73, PRDM16, and CHD5 already validated. Our CpG methylome analysis identified a silenced 1p36.3 gene KIAA0495, previously thought coding long non-coding RNA. We found that the open reading frame 2 of KIAA0495 is actually protein-coding and translating, encoding a small protein SP0495. KIAA0495 transcript is broadly expressed in multiple normal tissues, but frequently silenced by promoter CpG methylation in multiple tumor cell lines and primary tumors including colorectal, esophageal and breast cancers. Its downregulation/methylation is associated with poor survival of cancer patients. SP0495 induces tumor cell apoptosis, cell cycle arrest, senescence and autophagy, and inhibits tumor cell growth in vitro and in vivo. Mechanistically, SP0495 binds to phosphoinositides (PtdIns(3)P, PtdIns(3,5)P2) as a lipid-binding protein, inhibits AKT phosphorylation and its downstream signaling, and further represses oncogenic AKT/mTOR, NF-κB, and Wnt/β-catenin signaling. SP0495 also regulates the stability of autophagy regulators BECN1 and SQSTM1/p62 through modulating phosphoinositides turnover and autophagic/proteasomal degradation. Thus, we discovered and validated a 1p36.3 small protein SP0495, functioning as a novel tumor suppressor regulating AKT signaling activation and autophagy as a phosphoinositide-binding protein, being frequently inactivated by promoter methylation in multiple tumors as a potential biomarker.

Towards a Multi-Omics of Male Infertility

Infertility is a common problem affecting one in six couples and in 30% of infertile couples, the male factor is a major cause. A large number of genes are involved in spermatogenesis and a significant proportion of male infertility phenotypes are of genetic origin. Studies on infertility have so far primarily focused on chromosomal abnormalities and sequence variants in protein-coding genes and have identified a large number of disease-associated genes. However, it has been shown that a multitude of factors across various omics levels also contribute to infertility phenotypes. The complexity of male infertility has led to the understanding that an integrated, multi-omics analysis may be optimal for unravelling this disease. While there is a vast array of different factors across omics levels associated with infertility, the present review focuses on known factors from the genomics, epigenomics, transcriptomics, proteomics, metabolomics, glycomics, lipidomics, miRNomics, and integrated omics levels. These include: repeat expansions in AR, POLG, ATXN1, DMPK, and SHBG, multiple SNPs, copy number variants in the AZF region, disregulated miRNAs, altered H3K9 methylation, differential MTHFR, MEG3, PEG1, and LIT1 methylation, altered protamine ratios and protein hypo/hyperphosphorylation. This integrative review presents a step towards a multi-omics approach to understanding the complex etiology of male infertility. Currently only a few genetic factors, namely chromosomal abnormalities and Y chromosome microdeletions, are routinely tested in infertile men undergoing intracytoplasmic sperm injection. A multi-omics approach to understanding infertility phenotypes may yield a more holistic view of the disease and contribute to the development of improved screening methods and treatment options. Therefore, beside discovering as of yet unknown genetic causes of infertility, integrating multiple fields of study could yield valuable contributions to the understanding of disease development. Future multi-omics studies will enable to synthesise fragmented information and facilitate biomarker discovery and treatments in male infertility.

Constructing a seventeen-gene signature model for non-obstructive azoospermia based on integrated transcriptome analyses and WGCNA

BACKGROUND

Non-obstructive azoospermia (NOA) affects approximately 1% of the male population worldwide. The underlying mechanism and gene transcription remain unclear. This study aims to explore the potential pathogenesis for the detection and management of NOA.

METHODS

Based on four microarray datasets from the Gene Expression Omnibus database, integrated analysis and weighted correlation network analysis (WGCNA) were used to obtain the intersected common differentially expressed genes (DESs). Differential signaling pathways were identified via GO and GSVA-KEGG analyses. We constructed a seventeen-gene signature model using least absolute shrinkage and selection operation (LASSO) regression, and validated its efficacy in another two GEO datasets. Three patients with NOA and three patients with obstructive azoospermia were recruited. The mRNA levels of seven key genes were measured in testicular samples, and the gene expression profile was evaluated in the Human Protein Atlas (HPA) database.

RESULTS

In total, 388 upregulated and 795 downregulated common DEGs were identified between the NOA and control groups. ATPase activity, tubulin binding, microtubule binding, and metabolism- and immune-associated signaling pathways were significantly enriched. A seventeen-gene signature predictive model was constructed, and receiver operating characteristic (ROC) analysis showed that the area under the curve (AUC) values were 1.000 (training group), 0.901 (testing group), and 0.940 (validation set). The AUCs of seven key genes (REC8, CPS1, DHX57, RRS1, GSTA4, SI, and COX7B) were all > 0.8 in both the testing group and the validation set. The qRT-PCR results showed that consistent with the sequencing data, the mRNA levels of RRS1, GSTA4, and COX7B were upregulated, while CPS1, DHX57, and SI were downregulated in NOA. Four genes (CPS1, DHX57, RRS1, and SI) showed significant differences. Expression data from the HPA database showed the localization characteristics and trajectories of seven key genes in spermatogenic cells, Sertoli cells, and Leydig cells.

CONCLUSIONS

Our findings suggest a novel seventeen-gene signature model with a favorable predictive power, and identify seven key genes with potential as NOA-associated marker genes. Our study provides a new perspective for exploring the underlying pathological mechanism in male infertility.

Novel mutations of TEX11 are associated with non-obstructive azoospermia

Non-obstructive azoospermia (NOA) affects 10% of infertile men worldwide, and genetic studies revealed that there are plenty of monogenic mutations that responsible for a part of idiopathic NOA cases. Testis-expressed gene 11 (TEX11) is an X-linked meiosis-specific gene, many pathogenic variants in TEX11 have been detected in NOA patients, and the deficiency of this gene can cause abnormal meiotic recombination and chromosomal synapsis. However, many NOA-affected cases caused by TEX11 mutation remain largely unknown. This study reported three novel TEX11 mutations (exon 5, c.313C>T: p.R105*), (exon 7, c.427A>C: p.K143Q) and (exon 29, c.2575G>A: p.G859R). Mutations were screened using whole-exome sequencing (WES) and further verified by amplifying and sequencing the specific exon. Histological analysis of testicular biopsy specimens revealed a thicker basement membrane of the seminiferous tubules and poorly developed spermatocytes, and no post-meiotic round spermatids or mature spermatozoa were observed in the seminiferous tubules of patients with TEX11 mutation.

Conclusion

This study presents three novel variants of TEX11 as potential infertility alleles that have not been previously reported. It expanded the variant spectrum of patients with NOA, which also emphasizes the necessity of this gene screening for the clinical auxiliary diagnosis of patients with azoospermia.

Beta-Meta: a meta-analysis application considering heterogeneity among genome-wide association studies

Many packages for a meta-analysis of genome-wide association studies (GWAS) have beendeveloped to discover genetic variants. Although variations across studies must be considered, there are not many currently-accessible packages that estimate between-study heterogeneity. Thus, we propose a python based application called Beta-Meta which can easilyprocess a meta-analysis by automatically selecting between a fixed effects and a randomeffects model based on heterogeneity. Beta-Meta implements flexible input data manipulation to allow multiple meta-analyses of different genotype-phenotype associations in asingle process. It provides a step-by-step meta-analysis of GWAS for each association inthe following order: heterogeneity test, two different calculations of an effect size and ap-value based on heterogeneity, and the Benjamini-Hochberg p-value adjustment. Thesemethods enable users to validate the results of individual studies with greater statisticalpower and better estimation precision. We elaborate on these and illustrate them with examples from several studies of infertility-related disorders.

Genome-Wide Association Screening Determines Peripheral Players in Male Fertility Maintenance

Deciphering the functional relationships of genes resulting from genome-wide screens for polymorphisms that are associated with phenotypic variations can be challenging. However, given the common association with certain phenotypes, a functional link should exist. We have tested this prediction in newly sequenced exomes of altogether 100 men representing different states of fertility. Fertile subjects presented with normal semen parameters and had naturally fathered offspring. In contrast, infertile probands were involuntarily childless and had reduced sperm quantity and quality. Genome-wide association study (GWAS) linked twelve non-synonymous single-nucleotide polymorphisms (SNPs) to fertility variation between both cohorts. The SNPs localized to nine genes for which previous evidence is in line with a role in male fertility maintenance: ANAPC1, CES1, FAM131C, HLA-DRB1, KMT2C, NOMO1, SAA1, SRGAP2, and SUSD2. Most of the SNPs residing in these genes imply amino acid exchanges that should only moderately affect protein functionality. In addition, proteins encoded by genes from present GWAS occupied peripheral positions in a protein-protein interaction network, the backbone of which consisted of genes listed in the Online Mendelian Inheritance in Man (OMIM) database for their implication in male infertility. Suggestive of an indirect impact on male fertility, the genes focused were indeed linked to each other, albeit mediated by other interactants. Thus, the chances of identifying a central player in male infertility by GWAS could be limited in general. Furthermore, the SNPs determined and the genes containing these might prove to have potential as biomarkers in the diagnosis of male fertility.

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

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

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

Common Variation in the PIN1 Locus Increases the Genetic Risk to Suffer from Sertoli Cell-Only Syndrome

We aimed to analyze the role of the common genetic variants located in the PIN1 locus, a relevant prolyl isomerase required to control the proliferation of spermatogonial stem cells and the integrity of the blood–testis barrier, in the genetic risk of developing male infertility due to a severe spermatogenic failure (SPGF). Genotyping was performed using TaqMan genotyping assays for three PIN1 taggers (rs2287839, rs2233678 and rs62105751). The study cohort included 715 males diagnosed with SPGF and classified as suffering from non-obstructive azoospermia (NOA, n = 505) or severe oligospermia (SO, n = 210), and 1058 controls from the Iberian Peninsula. The allelic frequency differences between cases and controls were analyzed by the means of logistic regression models. A subtype specific genetic association with the subset of NOA patients classified as suffering from the Sertoli cell-only (SCO) syndrome was observed with the minor alleles showing strong risk effects for this subset (OR_addrs2287839 = 1.85 (1.17–2.93), OR_addrs2233678 = 1.62 (1.11–2.36), OR_addrs62105751 = 1.43 (1.06–1.93)). The causal variants were predicted to affect the binding of key transcription factors and to produce an altered PIN1 gene expression and isoform balance. In conclusion, common non-coding single-nucleotide polymorphisms located in PIN1 increase the genetic risk to develop SCO.

Advanced molecular approaches in male infertility diagnosis

In the recent years a special attention has been given to a major health concern namely to male infertility, defined as the inability to conceive after 12 months of regular unprotected sexual intercourse, taken into account the statistics that highlight that sperm counts have dropped by 50-60% in recent decades. According to the WHO, infertility affects approximately 9% of couples globally, and the male factor is believed to be present in roughly 50% of cases, with exclusive responsibility in 30%. The aim of this manuscript is to present an evidence-based approach for diagnosing male infertility that includes finding new solutions for diagnosis and critical outcomes, retrieving up-to-date studies and existing guidelines. The diverse factors that induce male infertility generated in a vast amount of data that needed to be analysed by a clinician before a decision could be made for each individual. Modern medicine faces numerous obstacles as a result of the massive amount of data generated by the molecular biology discipline. To address complex clinical problems, vast data must be collected, analysed, and used, which can be very challenging. The use of artificial intelligence (AI) methods to create a decision support system can help predict the diagnosis and guide treatment for infertile men, based on analysis of different data as environmental and lifestyle, clinical (sperm count, morphology, hormone testing, karyotype, etc.) and "omics" bigdata. Ultimately, the development of AI algorithms will assist clinicians in formulating diagnosis, making treatment decisions, and predicting outcomes for assisted reproduction techniques.

Genetic Association of the Functional WDR4 Gene in Male Fertility

Infertility is one of the important problems in the modern world. Male infertility is characterized by several clinical manifestations, including low sperm production (oligozoospermia), reduced sperm motility (asthenozoospermia), and abnormal sperm morphology (teratozoospermia). WDR4, known as Wuho, controls fertility in Drosophila. However, it is unclear whether WDR4 is associated with clinical manifestations of male fertility in human. Here, we attempted to determine the physiological functions of WDR4 gene. Two cohorts were applied to address this question. The first cohort was the general population from Taiwan Biobank. Genomic profiles from 68,948 individuals and 87 common physiological traits were applied for phenome-wide association studies (PheWAS). The second cohort comprised patients with male infertility from Wan Fang Hospital, Taipei Medical University. In total, 81 male participants were recruited for the genetic association study. Clinical records including gender, age, total testosterone, follicle-stimulating hormone (FSH), luteinizing hormone (LH), total sperm number, sperm motility, and sperm morphology were collected. In the first cohort, results from PheWAS exhibited no associations between WDR4 genetic variants and 87 common physiological traits. In the second cohort, a total of four tagging single-nucleotide polymorphisms (tSNPs) from WDR4 gene (rs2298666, rs465663, rs2248490, and rs3746939) were selected for genotyping. We found that SNP rs465663 solely associated with asthenozoospermia. Functional annotations through the GTEx portal revealed the correlation between TT or TC genotype and low expression of WDR4. Furthermore, we used mouse embryonic fibroblasts cells from mwdr4 heterozygous (+/‒) mice for functional validation by western blotting. Indeed, low expression of WDR4 contributed to ROS-induced DNA fragmentation. In conclusion, our results suggest a critical role of WDR4 gene variant as well as protein expression in asthenozoospermia.

RNA-binding protein ELAVL2 plays post-transcriptional roles in the regulation of spermatogonia proliferation and apoptosis

Objectives

RNA‐binding proteins (RBPs) play essential post‐transcriptional roles in regulating spermatogonial stem cells (SSCs) maintenance and differentiation. We identified a conserved and SSCs‐enriched RBP ELAVL2 from our single‐cell sequencing data, but its function and mechanism in SSCs were unclear.

Materials and methods

Expressions of ELAVL2 during human and mouse testis development were validated. Stable C18‐4 and TCam‐2 cell lines with overexpression and knockdown of ELAVL2 were established, which were applied to proliferation and apoptosis analysis. RNA immunoprecipitation and sequencing were used to identify ELAVL2 targets, and regulatory functions of ELAVL2 on target mRNAs were studied. Proteins interacting with ELAVL2 in human and mouse testes were identified using immunoprecipitation and mass spectrometric, which were validated by in vivo and in vitro experiments.

Results

ELAVL2 was testis‐enriched and preferentially expressed in human and mouse SSCs. ELAVL2 was down‐regulated in NOA patients. ELAVL2 promoted proliferation and inhibited apoptosis of C18‐4 and TCam‐2 cell lines via activating ERK and AKT pathways. ELAVL2 associated with mRNAs encoding essential regulators of SSCs proliferation and survival, and promoted their protein expression at post‐transcriptional level. ELAVL2 interacted with DAZL in vivo and in vitro in both human and mouse testes.

Conclusions

Taken together, these results indicate that ELAVL2 is a conserved SSCs‐enriched RBP that down‐regulated in NOA, which regulates spermatogonia proliferation and apoptosis by promoting protein expression of targets.

Replicating a GWAS: two novel candidate markers for oligospermia in Greek population

Genome-wide association studies have paved the way for the discovery of new markers regarding many diseases, including male infertility. A previous study on Caucasians highlighted 172 polymorphisms for their putative association with male infertility and we attempted to replicate these findings on our dataset comprising of Greek male individuals (n = 360). We retrieved 59 out of 172 polymorphisms and tested for all association models on 278 normospermic men and 82 patients with an abnormal seminogram, later separated into oligozoospermic and asthenozoospermic groups. Our findings indicate that two SNPs (rs2296225 in KIF17, rs7224496 in SMYD4) are associated with male infertility in the Greek population and have not been recorded in literature as of yet. These novel markers need further validation via additional studies and an increased individual number. All in all, replication studies, possess the power to validate existing polymorphisms found across all population and thus increase both statistical significance as well as identify novel potentially diagnostic markers.

Effect and in silico characterization of genetic variants associated with severe spermatogenic disorders in a large Iberian cohort

BACKGROUND

Severe spermatogenic failure (SpF) represents the most extreme manifestation of male infertility, as it decreases drastically the semen quality leading to either severe oligospermia (SO, <5 million spermatozoa/mL semen) or non-obstructive azoospermia (NOA, complete lack of spermatozoa in the ejaculate without obstructive causes).

OBJECTIVES

The main objective of the present study is to analyze in the Iberian population the effect of 6 single-nucleotide polymorphisms (SNPs) previously associated with NOA in Han Chinese through genome-wide association studies (GWAS) and to establish their possible functional relevance in the development of specific SpF patterns.

MATERIALS AND METHODS

We genotyped 674 Iberian infertile men (including 480 NOA and 194 SO patients) and 1058 matched unaffected controls for the GWAS-associated variants PRMT6-rs12097821, PEX10-rs2477686, CDC42BPA-rs3000811, IL17A-rs13206743, ABLIM1-rs7099208, and SOX5-rs10842262. Their association with SpF, SO, NOA, and different NOA phenotypes was evaluated by logistic regression models, and their functional relevance was defined by comprehensive interrogation of public resources.

RESULTS

ABLIM1-rs7099208 was associated with SpF under both additive (OR = 0.86, p = 0.036) and dominant models (OR = 0.78, p = 0.026). The CDC42BPA-rs3000811 minor allele frequency was significantly increased in the subgroup of NOA patients showing maturation arrest (MA) of germ cells compared to the remaining NOA cases under the recessive model (OR = 4.45, p = 0.044). The PEX10-rs2477686 SNP was associated with a negative testicular sperm extraction (TESE) outcome under the additive model (OR = 1.32, p = 0.034). The analysis of functional annotations suggested that these variants affect the testis-specific expression of nearby genes and that lincRNA may play a role in SpF.

CONCLUSIONS

Our data support the association of three previously reported NOA risk variants in Asians (ABLIM1-rs7099208, CDC42BPA-rs3000811, and PEX10-rs2477686) with different manifestations of SpF in Iberians of European descent, likely by influencing gene expression and lincRNA deregulation.

Weighted Correlation Gene Network Analysis Reveals New Potential Mechanisms and Biomarkers in Non-obstructive Azoospermia

Non-obstructive azoospermia (NOA) denotes a severe form of male infertility, whose etiology is still poorly understood. This is mainly due to limited knowledge on the molecular mechanisms that lead to spermatogenesis failure. In this study, we acquired microarray data from GEO DataSets and identified differentially expressed genes using the limma package in R. We identified 1,261 differentially expressed genes between non-obstructive and obstructive azoospermia. Analysis of their possible biological functions and related signaling pathways using the cluster profiler package revealed an enrichment of genes involved in germ cell development, cilium organization, and oocyte meiosis. Immune infiltration analysis indicated that macrophages were the most significant immune component of NOA, cooperating with mast cells and natural killer cells. The weighted gene coexpression network analysis algorithm generated three related functional modules, which correlated closely with clinical parameters derived from histopathological subtypes of NOA. The resulting data enabled the construction of a protein–protein interaction network of these three modules, with CDK1, CDC20, CCNB1, CCNB2, and MAD2L1 identified as hub genes. This study provides the basis for further investigation of the molecular mechanism underlying NOA, as well as indications about potential biomarkers and therapeutic targets of NOA. Finally, using tissues containing different tissue types for differential expression analysis can reflect the expression differences in different tissues to a certain extent. But this difference in expression is only related and not causal. The specific causality needs to be verified later.

Novel Gene Regulation in Normal and Abnormal Spermatogenesis

Spermatogenesis is a complex and dynamic process which is precisely controlledby genetic and epigenetic factors. With the development of new technologies (e.g., single-cell RNA sequencing), increasingly more regulatory genes related to spermatogenesis have been identified. In this review, we address the roles and mechanisms of novel genes in regulating the normal and abnormal spermatogenesis. Specifically, we discussed the functions and signaling pathways of key new genes in mediating the proliferation, differentiation, and apoptosis of rodent and human spermatogonial stem cells (SSCs), as well as in controlling the meiosis of spermatocytes and other germ cells. Additionally, we summarized the gene regulation in the abnormal testicular microenvironment or the niche by Sertoli cells, peritubular myoid cells, and Leydig cells. Finally, we pointed out the future directions for investigating the molecular mechanisms underlying human spermatogenesis. This review could offer novel insights into genetic regulation in the normal and abnormal spermatogenesis, and it provides new molecular targets for gene therapy of male infertility.

Strategies to Identify Genetic Variants Causing Infertility

Genetic causes are thought to underlie about half of infertility cases, but understanding the genetic bases has been a major challenge. Modern genomics tools allow more sophisticated exploration of genetic causes of infertility through population, family-based, and individual studies. Nevertheless, potential therapies based on genetic diagnostics will be limited until there is certainty regarding the causality of genetic variants identified in an individual. Genome modulation and editing technologies have revolutionized our ability to functionally test such variants, and also provide a potential means for clinical correction of infertility variants. This review addresses strategies being used to identify causative variants of infertility.

Association study between single-nucleotide variants rs12097821, rs2477686, and rs10842262 and idiopathic male infertility risk in Serbian population with meta-analysis

PURPOSE

A genome-wide association study conducted in the Han Chinese population identified three single nucleotide variants rs12097821, rs2477686, and rs10842262 as being significantly associated with non-obstructive azoospermia. Our aim was to evaluate the possible association between these susceptibility loci and idiopathic male infertility risk in the Serbian population.

METHODS

A case-control study was conducted on 431 male individuals from the Serbian population divided into two groups. The case group consisted of 208 males diagnosed with oligoasthenozoospermia or non-obstructive azoospermia, while the control group involved 223 fertile men who have fathered at least one child.

RESULTS

According to codominant (P_codom = 0.048, OR_codom = 0.57, 95%CI 0.35-0.92) and overdominant (P_overdom = 0.017, OR_overdom = 0.62, 95%CI 0.42-0.92) genetic models, rs10842262 was found to be associated with male infertility. Stratifying infertile men according to diagnosis yielded statistically significant results for non-obstructive azoospermia cases under multiple genetic models (P_codom = 0.038, OR_codom = 0.47, 95%CI 0.26-0.85; P_dom = 0.031, OR_dom = 0.53, 95%CI 0.30-0.94; P_overdom = 0.016, OR_overdom = 0.55, 95%CI 0.33-0.90). Minor allele C of rs2477686 genetic variant was shown to be associated with the reduced risk of oligoasthenozoospermia under the log-additive genetic model (P = 0.03, OR = 0.69, 95%CI 0.50-0.97). The results of the meta-analysis indicate both rs2477686 and rs10842262 to be associated with male infertility.

CONCLUSION

Our results show variants rs2477686 and rs10842262 to be significantly associated with male infertility in the Serbian population. Nevertheless, case-control studies in other populations are needed to validate their association with infertility in males diagnosed with oligoasthenozoospermia and non-obstructive azoospermia.

MRI findings of nonobstructive azoospermia: lesions in and out of pelvic cavity

Nonobstructive azoospermia (NOA) can be caused by various diseases, including congenital disorders, endocrine disorders, infections, tumor or tumor-like diseases, vascular diseases, etc. Diagnosis of the underlying cause of NOA is complicated and challenging. In this study, we introduce an MR examination protocol for the etiological diagnosis of NOA, and demonstrate a series of NOA patients with different causes and imaging findings. Except for lesions of testes, the patients may also combine abnormalities of adrenal glands and central nervous system. In such cases, the patients could benefit from additional abdominal and intracranial scans.

Whole-exome sequencing of a large Chinese azoospermia and severe oligospermia cohort identifies novel infertility causative variants and genes

Rare coding variants have been proven to be one of the significant factors contributing to spermatogenic failure in patients with non-obstructive azoospermia (NOA) and severe oligospermia (SO). To delineate the molecular characteristics of idiopathic NOA and SO, we performed whole-exome sequencing of 314 unrelated patients of Chinese Han origin and verified our findings by comparing to 400 fertile controls. We detected six pathogenic/likely pathogenic variants and four variants of unknown significance, in genes known to cause NOA/SO, and 9 of which had not been earlier reported. Additionally, we identified 20 novel NOA candidate genes affecting 25 patients. Among them, five (BRDT, CHD5, MCM9, MLH3 and ZFX) were considered as strong candidates based on the evidence obtained from murine functional studies and human single-cell (sc)RNA-sequencing data. These genetic findings provide insight into the aetiology of human NOA/SO and pave the way for further functional analysis and molecular diagnosis of male infertility.

Human X chromosome exome sequencing identifies BCORL1 as contributor to spermatogenesis

BACKGROUND

Infertility affects approximately 15% of couples worldwide with male infertility being responsible for approximately 50% of cases. Although accumulating evidence demonstrates the critical role of the X chromosome in spermatogenesis during the last few decades, the expression patterns and potential impact of the X chromosome, together with X linked genes, on male infertility are less well understood.

METHODS

We performed X chromosome exome sequencing followed by a two-stage independent population validation in 1333 non-obstructive azoospermia cases and 1141 healthy controls to identify variant classes with high likelihood of pathogenicity. To explore the functions of these candidate genes in spermatogenesis, we first knocked down these candidate genes individually in mouse spermatogonial stem cells (SSCs) using short interfering RNA oligonucleotides and then generated candidate genes knockout mice by CRISPR-Cas9 system.

RESULTS

Four low-frequency variants were identified in four genes (BCORL1, MAP7D3, ARMCX4 and H2BFWT) associated with male infertility. Functional studies of the mouse SSCs revealed that knocking down Bcorl1 or Mtap7d3 could inhibit SSCs self-renewal and knocking down Armcx4 could repress SSCs differentiation in vitro. Using CRISPR-Cas9 system, Bcorl1 and Mtap7d3 knockout mice were generated. Excitingly, Bcorl1 knockout mice were infertile with impaired spermatogenesis. Moreover, Bcorl1 knockout mice exhibited impaired sperm motility and sperm cells displayed abnormal mitochondrial structure.

CONCLUSION

Our data indicate that the X-linked genes are associated with male infertility and involved in regulating SSCs, which provides a new insight into the role of X-linked genes in spermatogenesis.

Long noncoding RNAs expression profile and long noncoding RNA-mediated competing endogenous RNA network in nonobstructive azoospermia patients

Aim: To analyze the expression profile and competing endogenous RNA (ceRNA) network of long noncoding RNAs (lncRNAs) in nonobstructive azoospermia (NOA). Materials & methods: The lncRNA expression profile in NOA was determined by microarray reanalysis. Differential expression analysis was performed by R software. The ceRNA network was constructed using correlation analysis and gene target miRNA prediction. Metascape was used for enrichment analysis. Again ceRNA network was validated by quantitative real-time PCR. Results: Many lncRNAs are differently expressed in NOA. LncRNAs might participate in spermatogenesis through ceRNA mechanism. The ceRNA network included male gamete generation and other pathways. LINC00467 in the network regulated the expression of LRGUK and TDRD6. Conclusion: LncRNAs are involved in NOA and potential biomarkers and therapeutic targets for NOA.

Testicular biopsies microarray analysis reveals circRNAs are involved in the pathogenesis of non-obstructive azoospermia

Circular RNAs (circRNAs) have been reported to be involved in many diseases. But there is no report on circRNAs in non-obstructive azoospermia (NOA). The purpose of this paper is to explore the circular RNA expression profile and potential functions of circRNAs in NOA patients. We first preformed circRNA expression profiling analysis using a circRNA microarray in testicular samples from NOA and obstructive azoospermia (OA) patients. CircRNAs were validated by qRT-PCR. Bioinformatics analysis were used to construct the ceRNA network. GO and KEGG enrichment analysis were performed by using DAVID. Microarray analysis identified 82 differentially expressed circRNAs in NOA specimens. The differential expression of hsa_circRNA_402130, hsa_circRNA_072697, hsa_circRNA_030050, hsa_circRNA_100812 and hsa_circRNA_406168 was confirmed by qRT-PCR. Enrichment analysis revealed the association of hsa_circRNA_402130 and hsa_circRNA_072697 with multiple signaling pathways. The data indicated that circRNAs were significantly dysregulated in NOA specimens and might involve in the pathogenesis of NOA.

Genetic Landscape of Nonobstructive Azoospermia and New Perspectives for the Clinic

Nonobstructive azoospermia (NOA) represents the most severe expression of male infertility, involving around 1% of the male population and 10% of infertile men. This condition is characterised by the inability of the testis to produce sperm cells, and it is considered to have an important genetic component. During the last two decades, different genetic anomalies, including microdeletions of the Y chromosome, karyotype defects, and missense mutations in genes involved in the reproductive function, have been described as the primary cause of NOA in many infertile men. However, these alterations only explain around 25% of azoospermic cases, with the remaining patients showing an idiopathic origin. Recent studies clearly suggest that the so-called idiopathic NOA has a complex aetiology with a polygenic inheritance, which may alter the spermatogenic process. Although we are far from a complete understanding of the molecular mechanisms underlying NOA, the use of the new technologies for genetic analysis has enabled a considerable increase in knowledge during the last years. In this review, we will provide a comprehensive and updated overview of the genetic basis of NOA, with a special focus on the possible application of the recent insights in clinical practice.

Recent advances in mammalian reproductive biology

Reproductive biology is a uniquely important topic since it is about germ cells, which are central for transmitting genetic information from generation to generation. In this review, we discuss recent advances in mammalian germ cell development, including preimplantation development, fetal germ cell development and postnatal development of oocytes and sperm. We also discuss the etiologies of female and male infertility and describe the emerging technologies for studying reproductive biology such as gene editing and single-cell technologies.

Genetics of male infertility

Male infertility is a multifactorial pathological condition affecting approximately 7% of the male population. The genetic landscape of male infertility is highly complex as semen and testis histological phenotypes are extremely heterogeneous, and at least 2,000 genes are involved in spermatogenesis. The highest frequency of known genetic factors contributing to male infertility (25%) is in azoospermia, but the number of identified genetic anomalies in other semen and aetiological categories is constantly growing. Genetic screening is relevant for its diagnostic value, clinical decision making, and appropriate genetic counselling. Anomalies in sex chromosomes have major roles in severe spermatogenic impairment. Autosome-linked gene mutations are mainly involved in central hypogonadism, monomorphic teratozoospermia or asthenozoospermia, congenital obstructive azoospermia, and familial cases of quantitative spermatogenic disturbances. Results from whole-genome association studies suggest a marginal role for common variants as causative factors; however, some of these variants can be important for pharmacogenetic purposes. Results of studies on copy number variations (CNVs) demonstrate a considerably higher CNV load in infertile patients than in normozoospermic men, whereas whole-exome analysis has proved to be a highly successful diagnostic tool in familial cases of male infertility. Despite such efforts, the aetiology of infertility remains unknown in about 40% of patients, and the discovery of novel genetic factors in idiopathic infertility is a major challenge for the field of androgenetics. Large, international, and consortium-based whole-exome and whole-genome studies are the most promising approach for the discovery of the missing genetic aetiology of idiopathic male infertility.

Targeted Next-Generation Sequencing Identifies Novel Sequence Variations of Genes Associated with Nonobstructive Azoospermia in the Han Population of Northeast China

Background

This study aimed to screen common and low-frequency variants of nonobstructive azoospermia (NOA)-associated genes, and to construct a database for NOA-associated single nucleotide variants (SNVs).

Material/Methods

Next-generation sequencing of 466 NOA-associated genes was performed in 34 patients with NOA (mean age, 29.06±4.49 years) and 40 sperm donors (mean age, 25.08±5.75 years) from the Han population of northeast China. The SNV database was constructed by summarizing NOA non-negatively-associated SNVs showing statistical differences between NOA cases and controls, and then selecting low-frequency variants using Baylor’s pipeline, to identify statistically valid SNVs.

Results

There were 65 SNVs identified that were significantly different between both groups (p<0.05). Five genetic variants showed positive correlations with NOA: MTRR c.537T>C (rs161870), odds ratios (OR), 3.686, 95% confidence interval (CI), 1.228–11.066; MTRR, c.1049A>G (rs162036), OR, 3.686, 95% CI, 1.228–11.066; PIWIL1, c.1580G>A (rs1106042), OR, 4.737, 95% CI, 1.314–17.072; TAF4B, c.1815T>C (rs1677016), OR, 3.599, 95% CI, 1.255–10.327; and SOX10 c.927T>C (rs139884), OR, 3.192, 95% CI, 1.220–8.353. Also, 52 NOA non-negatively associated SNVs and 39 SNVs were identified by Baylor’s pipeline and selected for the SNV database.

Conclusions

Five genetic variants were shown to have positive correlations with NOA. The SNV database constructed contained NOA non-negatively associated SNVs and low-frequency variants. This study showed that this approach was an effective strategy to identify risk alleles of NOA.

The arginine methyltransferase CARM1 represses p300•ACT•CREMτ activity and is required for spermiogenesis

CARM1 is a protein arginine methyltransferase (PRMT) that has been firmly implicated in transcriptional regulation. However, the molecular mechanisms by which CARM1 orchestrates transcriptional regulation are not fully understood, especially in a tissue-specific context. We found that Carm1 is highly expressed in the mouse testis and localizes to the nucleus in spermatids, suggesting an important role for Carm1 in spermiogenesis. Using a germline-specific conditional Carm1 knockout mouse model, we found that it is essential for the late stages of haploid germ cell development. Loss of Carm1 led to a low sperm count and deformed sperm heads that can be attributed to defective elongation of round spermatids. RNA-seq analysis of Carm1-null spermatids revealed that the deregulated genes fell into similar categories as those impacted by p300-loss, thus providing a link between Carm1 and p300. Importantly, p300 has long been known to be a major Carm1 substrate. We found that CREMτ, a key testis-specific transcription factor, associates with p300 through its activator, ACT, and that this interaction is negatively regulated by the methylation of p300 by Carm1. Thus, high nuclear Carm1 levels negatively impact the p300•ACT•CREMτ axis during late stages of spermiogenesis.

Semen quality is affected by HLA class I alleles together with sexually transmitted diseases

BACKGROUND

The human leukocyte antigen (HLA) locus includes several genes with key roles in antigen presentation and immune response, some of them inclusively found to be associated with non-obstructive azoospermia. Still, HLA connections to other infertility phenotypes such as semen hyperviscosity (SHV), asthenozoospermia (AST), and oligozoospermia (OLI) have been often neglected.

OBJECTIVES

In this work, we aimed to evaluate the association of HLA class I and II genes with SHV, AST, and OLI phenotypes while exploring a possible role in an adaptive immune response to sexually transmitted diseases (STD).

MATERIALS AND METHODS

Whole-exome sequencing was performed in a Portuguese cohort of 71 infertility cases and 68 controls, followed by HLA typing using a specific software-HLA*PRG:LA tool. Molecular screenings of seven STD were carried out in a subset of 72 samples (30 cases and 42 controls).

RESULTS

Statistical tests uncovered three protective alleles: HLA-A*11:01, associated with all forms of male infertility (p = 0.0006); HLA-DQB1*03:02 with SHV and OLI (P_SHV   = 0.0303, P_OLI   = 0.0153); and HLA-A*29:02 with OLI (p = 0.0355), which was found to interfere in sperm number together with HPV (p = 0.0313). Five risk alleles were also identified: two linked with SHV (HLA-B*50:01, p = 0.0278; and HLA-C*06:02, p = 0.0461), another one with both SHV and OLI (HLA-DQA1*05:01, P_SHV   = 0.0444 and P_OLI =0.0265), and two with OLI (HLA-C*03:03, p = 0.0480; and HLA-DQB1*03:01, p = 0.0499). Here, HLA-C*03:03 carriers tend to be HPV infected.

CONCLUSIONS

The application of HLA*PRG:LA tool to the study of male infertility provided novel insights for an HLA correlation with semen quality, namely among SHV and OLI phenotypes. The discovery of an HLA-A*29:02/HPV crosstalk, together with former reports of HLA alleles conferring resistance-susceptibility to diverse human pathogens, raises the hypothesis of a mechanistic link between male infertility, HLA polymorphism, and host response to STD.

PEX10, SIRPA-SIRPG, and SOX5 gene polymorphisms are strongly associated with nonobstructive azoospermia susceptibility

PURPOSE

Male infertility is a multifactorial syndrome encompassing a wide variety of disorders. A previous Chinese genome-wide single-nucleotide polymorphism (SNP) association studies have identified four SNPs (rs12097821 in PRMT6 gene, rs2477686 in PEX10 gene, rs6080550 in SIRPA-SIRPG, and rs10842262 in SOX5 gene) as being significantly associated with risk factors for nonobstructive azoospermia (NOA). However, the results were not fully repeated in later studies, which calls for further investigations.

METHODS

We here performed a case-control study in a central Chinese population to explore the association between the four SNPs and male infertility, which included 631 infertile men (NOA and oligozoospermia) and 720 healthy fertile men. The genotyping was performed using the polymerase chain reaction-restriction fragment length polymorphism and confirmed by sequencing.

RESULTS

The results showed that rs12097821 and rs10842262 were strongly associated with the risk of NOA but not total male infertility or oligozoospermia, while rs2477686 and rs6080550 were not associated with the risk of total male infertility, NOA, or oligozoospermia. To improve the statistical strength, a meta-analysis was conducted. The results suggested that rs2477686, rs6080550, and rs10842262 were significantly associated with male infertility, especially with NOA, while rs12097821 was only found to be associated with total male infertility.

CONCLUSIONS

Collectively, the rs2477686, rs6080550, and rs10842262 may indeed be the genetic risk factors for NOA, which requires further investigation using larger independent sets of samples in different ethnic populations.

Ubiquitin-specific protease 26 (USP26) is not essential for mouse gametogenesis and fertility

Ubiquitin-specific protease 26 (USP26) is a deubiquitylating enzyme belonging to the USPs family with a transcription pattern restricted to the male germline. Since protein ubiquitination is an essential regulatory mechanism during meiosis, many efforts have been focused on elucidating the function of USP26 and its relationship with fertility. During the last decade, several studies have reported the presence of different polymorphisms in USP26 in patients with non-obstructive azoospermia (NOA) or severe oligozoospermia suggesting that this gene may be associated with human infertility. However, other studies have revealed the presence of these and novel polymorphisms, including nonsense mutations, in men with normal spermatogenesis as well. Thus, the results remain controversial and its function is unknown. In the present study, we describe the in vivo functional analysis of mice lacking USP26. The phenotypic analysis of two different Usp26-null mutants showed no overt-phenotype with both males and females being fertile. Cytological analysis of spermatocytes showed no defects in synapsis, chromosome dynamics, DNA repair, or recombination. Histopathological analysis revealed a normal distribution and number of the different cell types in both male and female mice. Finally, normal counts were observed in fertility assessments. These results represent the first in vivo evidence showing that USP26 is not essential for mouse gametogenesis.

Shorter leukocyte telomere length is associated with risk of nonobstructive azoospermia

OBJECTIVE

To determine the association between leukocyte telomere length and the risk of nonobstructive azoospermia (NOA).

DESIGN

The mean leukocyte telomere length (LTL) among men with NOA, obstructive azoospermia (OA), and normospermic subjects was determined by quantitative polymerase chain reaction (PCR). We used logistic regression to investigate the association between LTL and the risk of NOA after adjustment for age and body mass index (BMI). Partial correlation analysis was also used to evaluate the relationship of clinical parameters with the mean LTL among men with OA and NOA.

SETTING

Reproductive medicine center.

PATIENTS(S)

A total of 866 men, including 270 normospermic controls, 247 OA and 349 NOA patients.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

Leukocyte telomere length.

RESULT(S)

The mean relative LTL of men with NOA was significantly shorter than that of those with OA and in normospermic controls (odds ratio [OR] 0.81, 95% confidence interval [CI] 0.64-0.98 vs. OR 0.92, 95% CI 0.70-1.24 vs. OR 0.99, 95% CI 0.83-1.22), respectively). Subjects with shorter telomeres (lowest tertile) had a significantly higher risk of NOA than those with longer telomeres (highest tertile). Interestingly, we also found that a low relative LTL was associated with poor efficiency of spermatogenesis using the Johnsen score after testis biopsy and histopathology in azoospermic patients, after adjusting for patient age and BMI.

CONCLUSION(S)

This is the first report that short LTL is associated with NOA, shedding light on an important biological pathway involved in the etiology of this form of male factor infertility.

Fine mapping the MHC region identified rs4997052 as a new variant associated with nonobstructive azoospermia in Han Chinese males

OBJECTIVE

To investigate the association between genetic variants in the major histocompatibility complex (MHC) region and nonobstructive azoospermia (NOA) susceptibility.

DESIGN

MHC region fine-mapping analysis based on previous NOA genome-wide association study (GWAS) data.

SETTING

Medical university.

PATIENT(S)

Nine hundred and eighty-one men with NOA and 1,657 normal fertile male controls.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

The MHC region imputation assessed with SNP2HLA software, taking the specific Han-MHC database as a reference panel; statistical significance of the MHC variants calculated using logistic regression models; functional annotation based on online public databases; and phenotypic variances explained by specific groups of genetic variants estimated using the fixed effects model from individual associations.

RESULT(S)

Two independent risk loci, rs7194 (odds ratio [OR] 1.37) at MHC class II molecules and rs4997052 (OR 1.30) at MHC class I molecules, were identified. Functional annotation showed rs7194 may tag the effect of multiple amino acid residues and the expression of HLA-DQB1 and HLA-DRB1; while rs4997052 showed the effect of amino acid changes of HLA-B at position 116 as well as the expression of HLA-B and CCHCR1, which coexpressed with genes enriched in pathways of spermatogenesis and male gamete generation. The novel variant rs4997052 identified in our study can explain another approximately 0.66% of the phenotypic variances of NOA.

CONCLUSION(S)

We fine-mapped the MHC region and identified two loci that independently drove NOA susceptibility. These results provide a deeper understanding of the association mechanisms of MHC and NOA risk.

Taste receptor polymorphisms and male infertility

STUDY QUESTION

Are polymorphisms of taste receptor genes associated with male infertility?

SUMMARY ANSWER

This study has showed the associations between three single nucleotide polymorphisms (SNPs) in taste receptors genes (TASR) and male infertility.

WHAT IS KNOWN ALREADY

Recent studies showed the expression of taste receptors in the testis and in spermatozoa, suggesting their possible role in infertility. The vast genetic variability in taste genes results in a large degree of diversity in various human phenotypes.

STUDY DESIGN, SIZE, DURATION

In this study, we genotyped 19 SNPs in 12 taste related genes in a total of 494 Caucasian male patients undergoing semen evaluation at the Centre of Couple Sterility of the Siena University Hospital. Consecutive patients were enrolled during infertility investigations from October 2014 to February 2016.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Median age of the patients was 36 years (18-58) and 141 were smokers. Genotyping was performed using the allele-specific PCR. The statistical analysis was carried out using generalized linear model (GLM) to explore the association between age, smoking, the genetic polymorphisms and sperm parameters.

MAIN RESULTS AND THE ROLE OF CHANCE

We observed that the homozygous carriers of the (G) allele of the TAS2R14-rs3741843 polymorphism showed a decreased sperm progressive motility compared to heterozygotes and (A) homozygotes (P = 0.003). Moreover, the homozygous carriers of the (T) allele of the TAS2R3-rs11763979 SNP showed fewer normal acrosome compared with the heterozygous and the homozygous carriers of the (G) allele (P = 0.002). Multiple comparisons correction was applied and the Bonferroni-corrected critical P-value was = 0.003.

LIMITATIONS, REASONS FOR CAUTION

The analysis is restricted to SNPs within genes and to men of Caucasian ancestry.

WIDER IMPLICATIONS OF THE FINDINGS

In silico analyses strongly point towards a functional effect of the two SNPs: TAS2R14-rs3741843 regulates TAS2R43 expression, a gene that is involved in cilia motility and therefore could influences sperm mobility; the (T) allele of TAS2R3-rs11763979 increases the expression of the WEE2 antisense RNA one gene (WEE2-AS1). According to Genotype-Tissue Expression (GTEx) project the WEE2 gene is expressed in the testes where presumably it has the role of down regulating meiotic cell division. It is plausible to hypothesize that the WEE2-AS1 increased expression may down regulate WEE2 which in turn can alter the natural timing of sperm maturation increasing the number of abnormal sperm cells.

STUDY FUNDING/COMPETING INTEREST(S)

None.

Strong association of SLC1A1 and DPF3 gene variants with idiopathic male infertility in Han Chinese

Male infertility is a multifactorial syndrome encompassing a wide variety of disorders. In recent years, several genome-wide single-nucleotide polymorphism (SNP) association studies (GWAS) have been performed on azoospermia and/or oligozoospermia in different populations including two GWAS on nonobstructive azoospermia in China; however, the association of SNPs with idiopathic male infertility, especially asthenozoospermia and oligozoospermia, and their correlation with semen parameters are still not clear. To investigate genetic variants associated with idiopathic male infertility (asthenozoospermia, oligozoospermia, and oligoasthenozoospermia) in Chinese Han people, 20 candidate SNPs were selected from GWAS results and genotyped using the Sequenom MassARRAY assay. A total of 136 subfertile men and 456 healthy fertile men were recruited. rs6476866 in SLC1A1 (P = 1.919E-4, OR = 0.5905, 95% CI: 0.447–0.78) and rs10129954 in DPF3 (P = 0.0023, OR = 2.199, 95% CI: 1.311–3.689) were strongly associated with idiopathic male infertility. In addition, positive associations were observed between asthenozoospermia and rs215702 in LSM5 (P = 0.0016, OR = 1.479, 95% CI: 1.075–2.033) and between oligoasthenozoospermia and rs2477686 in PEX10 (P = 0.0011, OR = 2.935, 95% CI: 1.492–5.775). In addition, six SNPs (rs215702 in LSM5, rs6476866 in SLC1A1, rs10129954 in DPF3, rs1801133 in MTHFR, rs2477686 in PEX10, and rs10841496 in PED3A) were significantly correlated with semen quality alterations. Our results suggest that idiopathic male infertility in different ethnic groups may share the same mechanism or pathway. Cohort expansion and further mechanistic studies on the role of genetic factors that influence spermatogenesis and sperm progressive motility are suggested.

Copy number gain of VCX, X-linked multi-copy gene, leads to cell proliferation and apoptosis during spermatogenesis

Male factor infertility affects one-sixth of couples worldwide, and non-obstructive azoospermia (NOA) is one of the most severe forms. In recent years there has been increasing evidence to implicate the participation of X chromosome in the process of spermatogenesis. To uncover the roles of X-linked multi-copy genes in spermatogenesis, we performed systematic analysis of X-linked gene copy number variations (CNVs) and Y chromosome haplogrouping in 447 idiopathic NOA patients and 485 healthy controls. Interestingly, the frequency of individuals with abnormal level copy of Variable charge, X-linked (VCX) was significantly different between cases and controls after multiple test correction (p = 5.10 × 10⁻⁵). To discriminate the effect of gain/loss copies in these genes, we analyzed the frequency of X-linked multi-copy genes in subjects among subdivided groups. Our results demonstrated that individuals with increased copy numbers of Nuclear RNA export factor 2 (NXF2) (p = 9.21 × 10⁻⁸) and VCX (p = 1.97 × 10⁻⁴) conferred the risk of NOA. In vitro analysis demonstrated that increasing copy number of VCX could upregulate the gene expression and regulate cell proliferation and apoptosis. Our study establishes a robust association between the VCX CNVs and NOA risk.

Genome-wide association study identifies ERBB4 on 2q34 as a novel locus associated with sperm motility in Japanese men

Background

The decrease in sperm motility has a potent influence on fertilisation. Sperm motility, represented as the percentage of motile sperm in ejaculated sperms, is influenced by lifestyle habits or environmental factors and by inherited factors. However, genetic factors contributing to individual differences in sperm motility remain unclear. To identify genetic factors that influence human sperm motility, we performed a genome-wide association study (GWAS) of sperm motility.

Methods

A two-stage GWAS was conducted using 811 Japanese men in a discovery stage, followed by a replication study using an additional 779 Japanese men.

Results

In the two-staged GWAS, a single nucleotide polymorphism rs3791686 in the intron of gene for erb-b2 receptor tyrosine kinase 4 (ERBB4) on chromosome 2q34 was identified as a novel locus for sperm motility, as evident from the discovery and replication results using meta-analysis (β=−4.01, combined P=5.40×10⁻⁹).

Conclusions

Together with the previous evidence that Sertoli cell-specific Erbb4-knockout mice display an impaired ability to produce motile sperm, this finding provides the first genetic evidence for further investigation of the genome-wide significant association at the ERBB4 locus in larger studies across diverse human populations.

Efficient generation of functional haploid spermatids from human germline stem cells by three-dimensional-induced system

Generation of functional spermatids from human spermatogonial stem cells (SSCs) in vitro is of utmost importance for uncovering mechanisms underlying human germ cell development and treating infertility. Here we report a three-dimensional-induced (3D-I) system by which human SSCs were efficiently differentiated into functional haploid spermatids. Human SSCs were isolated and identified phenotypically. Meiotic chromatin spreads and DNA content assays revealed that spermatocytes and haploid cells were effectively generated from human SSCs by 3D-I system. Haploid cells derived from human SSCs harbored normal chromosomes and excluded Y chromosome microdeletions. RNA sequencing and bisulfite sequencing analyses reflected similarities in global gene profiles and DNA methylation in human SSCs-derived spermatids and normal round spermatids. Significantly, haploid spermatids generated from human SSCs via 3D-I system were capable of fertilizing mouse oocytes, which subsequently enabled the development of hybrid embryos. This study thus provides invaluable human male gametes for treating male infertility.

Transcriptome-wide association study revealed two novel genes associated with nonobstructive azoospermia in a Chinese population

OBJECTIVE

To investigate the associations between genetically cis-regulated gene expression levels and nonobstructive azoospermia (NOA) susceptibility.

DESIGN

Transcriptome-wide association study (TWAS).

SETTING

Medical university.

INTERVENTIONS

None.

MAIN OUTCOME MEASURE(S)

The cis-hg² values for each gene were estimated with GCTA software. The effect sizes of cis-single-nucleotide polymorphisms (SNPs) on gene expression were measured using GEMMA software. Gene expression levels were entered into our existing NOA GWAS cohort using GEMMA software. The TWAS P-values were calculated using logistic regression models.

RESULT(S)

Expression levels of 1,296 cis-heritable genes were entered into our existing NOA GWAS data. The TWAS results identified two novel genes as statistically significantly associated with NOA susceptibility: PILRA and ZNF676. In addition, 6p21.32, previously reported in NOA GWAS, was further validated to be a susceptible region to NOA risk.

CONCLUSION(S)

Analysis with TWAS provides fruitful targets for follow-up functional studies.

Association between JMJD1A Expression and Sperm Retrieval in Non-Obstructive Azoospermic Patients

Identification of molecular markers which can predict the outcome of sperm retrieval non-invasively in patients with non-obstructive azoospermia (NOA) are valuable in clinical andrology. Jumonji domain-containing 1a (JMJD1A) is a significant epigenetic regulator during spermatogenesis, which plays an important role in the differentiation of post-meiotic germ cells into mature spermatozoa. We therefore aimed to examine the potential association between JMJD1A expression and the outcome of sperm retrieval in patients with NOA. Testicular biopsy specimens from 50 NOA patients with either successful sperm retrieval (sperm+, n=22) or failed sperm retrieval (sperm-, n=28) were collected and then examined for JMJD1A expression by reverse transcription-quantitative polymerase chain reaction (RT-qPCR). In addition, conventional clinical parameters including luteinizing hormone, follicle-stimulating hormone, testosterone, age, and testicular volume were compared between the two NOA groups. The expression of JMJD1A in the sperm+ group was significantly higher than in the sperm- group (P<0.001), however, no significant difference was observed between the two groups in clinical parameters. The receiver operating characteristic (ROC) curve of JMJD1A expression in predicting the sperm retrieval outcome showed a sensitivity of 90.91% and a specificity of 89.29% with significant discriminatory ability between the sperm+ and sperm- groups [area under the ROC curve (AUC)= 0.91]. This study demonstrates a significant association between the expression of JMJD1A and the success of sperm recovery in patients with NOA, and thus suggests that JMJD1A expression quantification in testicular biopsies may be a valuable biomarker along with conventional parameters in predicting the presence of spermatozoa.

Association of TUSC1 and DPF3 gene polymorphisms with male infertility

PURPOSE

Recently, genome-wide association studies of a Hutterite population in the USA revealed that five single nucleotide polymorphisms (SNPs) with a significant association with sperm quality and/or function in ethnically diverse men from Chicago were significantly correlated with family size. Of these, three SNPs (rs7867029, rs7174015, and rs12870438) were found to be significantly associated with the risk of azoospermia and/or oligozoospermia in a Japanese population. In this study, we investigated whether the rs10966811 (located in an intergenic region between the TUSC1 and IZUMO3 genes) and rs10129954 (located in the DPF3 gene) SNPs, previously related to family size, are associated with male infertility. In addition, we performed association analysis between rs12348 in TUSC1 and rs2772579 in IZUMO3 and male infertility.

METHODS

We genotyped 145 patients with infertility (including 83 patients with azoospermia and 62 with oligozoospermia) and 713 fertile controls by PCR-RFLP technique for polymorphism. Because rs10966811 has no restriction sites, the SNP rs12376894 with strong linkage disequilibrium was selected as an alternative to rs10966811.

RESULTS

There was a statistically significant association between rs12376894 proxy SNP of rs10966811 and oligozoospermia. Also, a statistically significant association between rs10129954 and azoospermia, and oligozoospermia was observed. When we assessed the relationship between rs12348 in TUSC1 and rs2772579 in IZUMO3 and male infertility traits, we found that rs12348 in TUSC1 was significantly associated with azoospermia and oligozoospermia, but rs2772579 in IZUMO3 was not associated with male infertility.

CONCLUSION

We found that the polymorphisms in TUSC1 and DPF3 displayed strong associations with male infertility.

Distinct Expression Profiles and Novel Targets of MicroRNAs in Human Spermatogonia, Pachytene Spermatocytes, and Round Spermatids between OA Patients and NOA Patients

Human spermatogenesis includes three main stages, namely, the mitosis of spermatogonia, meiosis of spermatocytes, and spermiogenesis of spermatids, which are precisely regulated by epigenetic and genetic factors. Abnormality of epigenetic and genetic factors can result in aberrant spermatogenesis and eventual male infertility. However, epigenetic regulators in controlling each stage of normal and abnormal human spermatogenesis remain unknown. Here, we have revealed for the first time the distinct microRNA profiles in human spermatogonia, pachytene spermatocytes, and round spermatids between obstructive azoospermia (OA) patients and non-obstructive azoospermia (NOA) patients. Human spermatogonia, pachytene spermatocytes, and round spermatids from OA patients and NOA patients were isolated using STA-PUT velocity sedimentation and identified by numerous hallmarks for these cells. RNA deep sequencing showed that 396 microRNAs were differentially expressed in human spermatogonia between OA patients and NOA patients and 395 differentially expressed microRNAs were found in human pachytene spermatocytes between OA patients and NOA patients. Moreover, 378 microRNAs were differentially expressed in human round spermatids between OA patients and NOA patients. The differential expression of numerous microRNAs identified by RNA deep sequencing was verified by real-time PCR. Moreover, a number of novel targeting genes for microRNAs were predicted using various kinds of software and further verified by real-time PCR. This study thus sheds novel insights into epigenetic regulation of human normal spermatogenesis and the etiology of azoospermia, and it could offer new targets for molecular therapy to treat male infertility.