New insights into the genetics of spermatogenic failure: a review of the literature

SEPT14 complexes maintain sperm morphogenesis and function

Mutations in the septin (SEPT) family lead to male infertility. Septin 14 (SEPT14) is abundantly expressed in the testis, and its expression is significantly reduced in individuals with teratozoospermia, suggesting that SEPT14 may play a role in spermatogenesis. Here, we demonstrated that Sept14 is expressed mainly at the acroplaxome, manchette, neck, and annulus during spermiogenesis. To study the role of SEPT14 in sperm morphogenesis and function, the Sept14 knockout (Sept14-/-) mice were generated. The Sept14-/- male mice were subfertile and presented phenotypes such as irregular acrosomes, DNA damage, disorganized mitochondria, and displaced annuli. These abnormalities contributed to reduced sperm motility and impaired capacitation. Mechanistically, in the sperm head, SEPT14 interacted and colocalized with microtubules and actin during the manchette formation at the sperm metamorphosis phase. In the annulus, SEPT14 interacted with SEPT9, SEPT7, and SEPT2 to form the septin filaments to maintain the localization of the annulus. The GTP-binding domain (GBD) of SEPT14 interacted with the GBD of SEPT2, whereas the C-terminus of SEPT14 interacted with the GBD of SEPT7. Thus, our study reveals a role of SEPT14 in mediating sperm morphogenesis.

Mitochondrial dysfunction signatures in idiopathic primary male infertility: a validated proteomics-based diagnostic approach

Research question

Male infertility accounts for almost half of all infertility cases worldwide, with idiopathic male infertility accounting for up to 30% of the cases. Sperm proteomics has revealed critical molecular pathway changes in men with infertility. However, the sperm mitochondrial proteome remains poorly understood. We attempted to answer the following question: Do patients with idiopathic primary male infertility exhibit a proteomic signature associated with mitochondrial dysfunction that could be used as a target for future mechanistic investigations?

Design

Patients with idiopathic primary infertility (20-40 years old) referred to the Cleveland Clinic between March 2012 and April 2014 were compared with fertile donor controls. Sperm proteins were analyzed using sodium dodecyl sulphate-polyacrylamide gel electrophoresis page (SDS-PAGE) and liquid chromatography-mass spectrometry (LC-MS), and differentially expressed proteins (DEPs) were identified based on significance test results and fold change thresholds. Protein expression was validated using western blotting.

Results

Proteomic analysis of pooled samples from fertile donors (n = 5) and patients with idiopathic primary infertility (n = 5) identified 1,134 proteins, including 344 DEPs. Mitochondrial dysfunction topped the ingenuity toxicity list. Analysis of expression levels of three mitochondrial proteins known to combat oxidative stress revealed that peroxiredoxin-5 (PRDX5) and superoxide dismutase 2 (SOD2), but not glutathione disulphide reductase, were significantly decreased in patient samples compared with those in fertile-donor samples.

Conclusions

This study revealed an association of downregulated expression of PRDX5 and SOD2 in sperm samples of patients with idiopathic primary male infertility. Our results support future mechanistic studies and development of advanced diagnostic methods to better identify men with mitochondria-related male infertility.

Human-specific epigenomic states in spermatogenesis

Infertility is becoming increasingly common, affecting one in six people globally. Half of these cases can be attributed to male factors, many driven by abnormalities in the process of sperm development. Emerging evidence from genome-wide association studies, genetic screening of patient cohorts, and animal models highlights an important genetic contribution to spermatogenic defects, but comprehensive identification and characterization of the genes critical for male fertility remain lacking. High divergence of gene regulation in spermatogenic cells across species poses challenges for delineating the genetic pathways required for human spermatogenesis using common model organisms. In this study, we leveraged post-translational histone modification and gene transcription data for 15,491 genes in four mammalian species (human, rhesus macaque, mouse, and opossum), to identify human-specific patterns of gene regulation during spermatogenesis. We combined H3K27me3 ChIP-seq, H3K4me3 ChIP-seq, and RNA-seq data to define epigenetic states for each gene at two stages of spermatogenesis, pachytene spermatocytes and round spermatids, in each species. We identified 239 genes that are uniquely active, poised, or dynamically regulated in human spermatogenic cells distinct from the other three species. While some of these genes have been implicated in reproductive functions, many more have not yet been associated with human infertility and may be candidates for further molecular and epidemiologic studies. Our analysis offers an example of the opportunities provided by evolutionary and epigenomic data for broadly screening candidate genes implicated in reproduction, which might lead to discoveries of novel genetic targets for diagnosis and management of male infertility and male contraception.

A comprehensive study of common and rare genetic variants in spermatogenesis-related loci identifies new risk factors for idiopathic severe spermatogenic failure

STUDY QUESTION

Can genome-wide genotyping data be analysed using a hypothesis-driven approach to enhance the understanding of the genetic basis of severe spermatogenic failure (SPGF) in male infertility?

SUMMARY ANSWER

Our findings revealed a significant association between SPGF and the SHOC1 gene and identified three novel genes (PCSK4, AP3B1, and DLK1) along with 32 potentially pathogenic rare variants in 30 genes that contribute to this condition.

WHAT IS KNOWN ALREADY

SPGF is a major cause of male infertility, often with an unknown aetiology. SPGF can be due to either multifactorial causes, including both common genetic variants in multiple genes and environmental factors, or highly damaging rare variants. Next-generation sequencing methods are useful for identifying rare mutations that explain monogenic forms of SPGF. Genome-wide association studies (GWASs) have become essential approaches for deciphering the intricate genetic landscape of complex diseases, offering a cost-effective and rapid means to genotype millions of genetic variants. Novel methods have demonstrated that GWAS datasets can be used to infer rare coding variants that are causal for male infertility phenotypes. However, this approach has not been previously applied to characterize the genetic component of a whole case-control cohort.

STUDY DESIGN SIZE DURATION

We employed a hypothesis-driven approach focusing on all genetic variation identified, using a GWAS platform and subsequent genotype imputation, encompassing over 20 million polymorphisms and a total of 1571 SPGF patients and 2431 controls. Both common (minor allele frequency, MAF > 0.01) and rare (MAF < 0.01) variants were investigated within a total of 1797 loci with a reported role in spermatogenesis. This gene panel was meticulously assembled through comprehensive searches in the literature and various databases focused on male infertility genetics.

PARTICIPANTS/MATERIALS SETTING METHODS

This study involved a European cohort using previously and newly generated data. Our analysis consisted of three independent methods: (i) variant-wise association analyses using logistic regression models, (ii) gene-wise association analyses using combined multivariate and collapsing burden tests, and (iii) identification and characterisation of highly damaging rare coding variants showing homozygosity only in SPGF patients.

MAIN RESULTS AND THE ROLE OF CHANCE

The variant-wise analyses revealed an association between SPGF and SHOC1-rs12347237 (P = 4.15E-06, odds ratio = 2.66), which was likely explained by an altered binding affinity of key transcription factors in regulatory regions and the disruptive effect of coding variants within the gene. Three additional genes (PCSK4, AP3B1, and DLK1) were identified as novel relevant players in human male infertility using the gene-wise burden test approach (P < 5.56E-04). Furthermore, we linked a total of 32 potentially pathogenic and recessive coding variants of the selected genes to 35 different cases.

LARGE SCALE DATA

Publicly available via GWAS catalog (accession number: GCST90239721).

LIMITATIONS REASONS FOR CAUTION

The analysis of low-frequency variants presents challenges in achieving sufficient statistical power to detect genetic associations. Consequently, independent studies with larger sample sizes are essential to replicate our results. Additionally, the specific roles of the identified variants in the pathogenic mechanisms of SPGF should be assessed through functional experiments.

WIDER IMPLICATIONS OF THE FINDINGS

Our findings highlight the benefit of using GWAS genotyping to screen for both common and rare variants potentially implicated in idiopathic cases of SPGF, whether due to complex or monogenic causes. The discovery of novel genetic risk factors for SPGF and the elucidation of the underlying genetic causes provide new perspectives for personalized medicine and reproductive counselling.

STUDY FUNDING/COMPETING INTERESTS

This work was supported by the Spanish Ministry of Science and Innovation through the Spanish National Plan for Scientific and Technical Research and Innovation (PID2020-120157RB-I00) and the Andalusian Government through the research projects of 'Plan Andaluz de Investigación, Desarrollo e Innovación (PAIDI 2020)' (ref. PY20_00212) and 'Proyectos de Investigación aplicada FEDER-UGR 2023' (ref. C-CTS-273-UGR23). S.G.-M. was funded by the previously mentioned projects (ref. PY20_00212 and PID2020-120157RB-I00). A.G.-J. was funded by MCIN/AEI/10.13039/501100011033 and FSE 'El FSE invierte en tu futuro' (grant ref. FPU20/02926). IPATIMUP integrates the i3S Research Unit, which is partially supported by the Portuguese Foundation for Science and Technology (FCT), financed by the European Social Funds (COMPETE-FEDER) and National Funds (projects PEstC/SAU/LA0003/2013 and POCI-01-0145-FEDER-007274). S.S. is supported by FCT funds (10.54499/DL57/2016/CP1363/CT0019), ToxOmics-Centre for Toxicogenomics and Human Health, Genetics, Oncology and Human Toxicology, and is also partially supported by the Portuguese Foundation for Science and Technology (UIDP/00009/2020 and UIDB/00009/2020). S. Larriba received support from Instituto de Salud Carlos III (grant: DTS18/00101), co-funded by FEDER funds/European Regional Development Fund (ERDF)-a way to build Europe) and from 'Generalitat de Catalunya' (grant 2021SGR052). S. Larriba is also sponsored by the 'Researchers Consolidation Program' from the SNS-Dpt. Salut Generalitat de Catalunya (Exp. CES09/020). All authors declare no conflict of interest related to this study.

Single nucleotide polymorphisms of CFAP43 and TEX14 associated with idiopathic male infertility in a Vietnamese population

Male infertility is a multifactorial disease due to spermatogenesis impairment, with etiology remaining unknown for roughly one-third of infertile cases. Several studies have demonstrated that genetic variants are male infertility risk factors. CFAP43 and TEX14 are involved in the spermatogenesis process. The present study aimed to assess the association between single-nucleotide polymorphisms (SNPs) in CFAP43 (rs17116635 and rs10883979) and TEX14 (rs79813370 and rs34818467) and idiopathic male infertility in a Vietnamese population. A cohort of 206 infertile men and 195 controls were recruited for the study. CFAP43 and TEX14 SNPs were genotyped using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). Genotypes of randomly selected samples, accounting for 10% of the total, were confirmed using Sanger sequencing. The obtained data were analyzed using statistical methods. The results showed that 4 SNPs (rs17116635, rs10883979, rs79813370, and rs34818467) were in accordance with Hardy-Weinberg Equilibrium (HWE; P > .05). CFAP43 rs10883979 and TEX14 rs79813370 were associated with male infertility. For CFAP43 rs10883979, in the recessive model, the combination AA + AG was associated with male infertility when compared to the GG genotype (OR = 0.26; 95% CI: 0.06-0.85; P = .02). For TEX14 rs79813370, a protective effect against infertility risk was identified in the presence of the T allele of rs79813370 when compared to the G allele (OR = 0.48; 95% CI: 0.32-0.72; P < .001). Our results suggest that CFAP43 rs10883979 and TEX14 rs79813370 are likely associated with male infertility in the Vietnamese population, in which the G allele of rs79813370 may be a risk factor for male infertility.

Molecular characterization of DNAH6 and ATPase6 (Mitochondrial DNA) genes in asthenozoospermia patients in the northern region of India

BACKGROUND

Male infertility due to spermatogenesis defects affects millions of men worldwide. However, the genetic etiology of the vast majority remains unclear. The present study was undertaken to assess the association of DNAH6 and ATPase6 genes in asthenozoospermia patients in the northern region of India.

METHODS

A total of 60 semen samples were collected for the study, of which 30 were from the case group and 30 were from the control group. The semen samples for the case group (asthenozoospermia) and control groups were collected from IVF and Reproductive Biology Centre, Maulana Azad Medical College, New Delhi. Sperm count and motility were classified as per World Health Organization (WHO 2021) protocol. A total genomic DNA was extracted as per the stranded TRIZOL method with little modification.

RESULTS

In-vitro molecular characterizations of DNAH6 and ATPase6 genes in both groups were checked by Polymerase Chain Reaction (PCR). The 675 bp and 375 bp amplicons were amplified using PCR for ATPase6 and DNAH6 genes. Our study results showed a significant (P ≤ 0.05) null deletion of DNAH6 and ATPase6 genes in asthenozoospermia patients as compared to the control. We found the significant null deletion of DNAH6 in case 45.0%, and the control group was 11.7%. However, in the case of APTase6, it was 26.7% and 10.0%, respectively.

CONCLUSIONS

Our study concluded that the presence of DHAH6 and ATPase6 genes had a significant impact on male infertility.

Behind the Genetics: The Role of Epigenetics in Infertility-Related Testicular Dysfunction

In recent decades, we have witnessed a progressive decline in male fertility. This is partly related to the increased prevalence of chronic diseases (e.g., obesity and diabetes mellitus) and risky lifestyle behaviors. These conditions alter male fertility through various non-genetic mechanisms. However, there is increasing evidence that they are also capable of causing sperm epigenetic alterations, which, in turn, can cause infertility. Furthermore, these modifications could be transmitted to offspring, altering their general and reproductive health. Therefore, these epigenetic modifications could represent one of the causes of the progressive decline in sperm count recorded in recent decades. This review focuses on highlighting epigenetic modifications at the sperm level induced by non-genetic causes of infertility. In detail, the effects on DNA methylation, histone modifications, and the expression profiles of non-coding RNAs are evaluated. Finally, a focus on the risk of transgenerational inheritance is presented. Our narrative review aims to demonstrate how certain conditions can alter gene expression, potentially leading to the transmission of anomalies to future generations. It emphasizes the importance of the early detection and treatment of reversible conditions (such as obesity and varicocele) and the modification of risky lifestyle behaviors. Addressing these issues is crucial for individual health, in preserving fertility, and in ensuring the well-being of future generations.

Identification and involvement of DAX1 gene in spermatogenesis of boring giant clam Tridacna crocea

DAX1 (dosage-sensitive sex reversal, adrenal hypoplasia congenital critical region on X chromosome gene 1), a key sex determinant in various species, plays a vital role in gonad differentiation and development and controls spermatogenesis. However, the identity and function of DAX1 are still unclear in bivalves. In the present study, we identified a DAX1 (designed as Tc-DAX1) gene from the boring giant clam Tridacna crocea, a tropical marine bivalve. The full length of Tc-DAX1 was 1877 bp, encoding 462 amino acids, with a Molecular weight of 51.81 kDa and a theoretical Isoelectric point of 5.87 (pI). Multiple sequence alignments and phylogenetic analysis indicated a putative ligand binding domain (LBD) conserved regions clustered with molluscans DAX1 homologs. The tissue distributions in different reproductive stages revealed a dimorphic pattern, with the highest expression trend in the male reproductive stage, indicating its role in spermatogenesis. The DAX1 expression data from embryonic stages shows its highest expression profile (P < 0.05) in the zygote stage, followed by decreasing trends in the larvae stages (P > 0.05). The localization of DAX1 transcripts has also been confirmed by whole mount in situ hybridization, showing high positive signals in the fertilized egg, 2, and 4-cell stage, and gastrula. Moreover, RNAi knockdown of the Tc-DAX1 transcripts shows a significantly lower expression profile in the ds-DAX1 group compared to the ds-EGFP group. Subsequent histological analysis of gonads revealed that spermatogenesis was affected in a ds-DAX1 group compared to the ds-EGFP group. All these results indicate that Tc-DAX1 is involved in the spermatogenesis and early embryonic development of T. crocea, providing valuable information for the breeding and aquaculture of giant clams.

Human circBOULE RNAs as potential biomarkers for sperm quality and male infertility

Reliable molecular biomarkers to predict fertility remain scarce. The current study explored the potential of testis-specific circBOULE RNAs as biomarkers for male infertility and sperm quality. Using RT-PCR and RT-qPCR assays, we identified seven circular RNAs from the human BOULE gene in human sperm. We found that sperm circEx3-6 RNA exhibited a significantly decreased expression in asthenozoospermia while circEx2-6 and circEx2-7 expression decreased in teratozoospermia, compared with the controls. Furthermore, circEx2-6 expression exhibited a negative correlation with sperm DNA Fragmentation Index (DFI), and circEx2-7 levels were correlated with both fertilization and cleavage rates involving assisted reproductive technologies. Further functional analyses in a transgenic fly model lent support for the roles of circBOULE RNAs in sperm development and human fertility. Collectively, our findings support that sperm circBOULE RNAs may serve as diagnostic biomarkers for assessing sperm motility and DNA quality. Hence clinical application and significance of sperm circular RNAs in assisted reproductive technologies warrant further investigation.

AKAP3-mediated type I PKA signaling is required for mouse sperm hyperactivation and fertility†

The protein kinase A (PKA) signaling pathway, which mediates protein phosphorylation, is important for sperm motility and male fertility. This process relies on A-kinase anchoring proteins that organize PKA and its signalosomes within specific subcellular compartments. Previously, it was found that the absence of A-kinase anchoring protein 3 (AKAP3) leads to multiple morphological abnormalities in mouse sperm. But how AKAP3 regulates sperm motility is yet to be elucidated. AKAP3 has two amphipathic domains, here named dual and RI, in its N-terminus. These domains are responsible for binding regulatory subunits I alpha (RIα) and II alpha (RIIα) of PKA and for RIα only, respectively. Here, we generated mutant mice lacking the dual and RI domains of AKAP3. It was found that the deletion of these domains caused male mouse infertile, accompanied by mild defects in the fibrous sheath of sperm tails. Additionally, the levels of serine/threonine phosphorylation of PKA substrates and tyrosine phosphorylation decreased in the mutant sperm, which exhibited a defect in hyperactivation under capacitation conditions. The protein levels of PKA subunits remained unchanged. But, interestingly, the regulatory subunit RIα was mis-localized from principal piece to midpiece of sperm tail, whereas this was not observed for RIIα. Further protein-protein interaction assays revealed a preference for AKAP3 to bind RIα over RIIα. Collectively, our findings suggest that AKAP3 is important for sperm hyperactivity by regulating type-I PKA signaling pathway mediated protein phosphorylation via its dual and RI domains.

Correlation between LHCGR and NR5A1 genes polymorphism and male infertility risk

INTRODUCTION

Infertility is one of the important phenomena in human reproduction. Genetic factors are the most important cause of male infertility. Here, we aimed to investigate the correlation between idiopathic male infertility and SNPs of the LHCGR (rs2293275) and NR5A1 (rs1057517779) genes in the Iranian-Azeri population.

METHODS

This case-control study consisted of 100 males with infertility and 100 healthy males from the Iranian Azeri population. Genomic DNA isolation from whole blood samples and Tetra-primer amplification refractory mutation system-polymerase chain reaction (Tetra-ARMS-PCR) method was used for genotyping. The data analysis was performed by chi-square (χ2) and Fisher's exact tests.

RESULTS

Genotyping analysis for LHCGR (rs2293275) polymorphism indicated that the frequency of C in the case group was significantly higher than in the control group (P < .05). Moreover, genotyping analysis for NR5A1 (rs1057517779) polymorphism indicated that the frequencies of the A allele and heterozygote GA genotype in the case group were significantly higher than those in the control group (P < .05).

CONCLUSION

Our study demonstrated that the SNPs of LHCGR (rs2293275) and NR5A1 (rs1057517779) genes may play a critical role in male infertility in the Iranian Azeri population. However, further studies on other ethnic origins with larger sample sizes are essential for accessing more accurate results. Moreover, functional experiments might be needed to understand the role of these polymorphisms in the molecular pathways involved in male fertility.

Antioxidants for male infertility: therapeutic scheme and indications. A retrospective single-center real-life study

BACKGROUND

This single-center real-life study was conducted to evaluate the most effective combination of nutraceuticals and the most appropriate indications for the treatment of male infertile patients.

METHODS

Infertile patients aged 20-55 years were treated with a combination of antioxidants (Androlen®; Enfarma, Misterbianco, Catania, Italy) (group A), with Androlen® (Enfarma) and a mixture of fibrinolytic molecules (Lenidase®, Enfarma) (group B), or Androlen® (Enfarma) and other molecules different from those used for the patients of the group B (group C). Patients were also subdivided according to the presence of varicocele, mild testicular hypotrophy, idiopathic infertility, and chronic male accessory gland infection.

RESULTS

Forty-three patients were enrolled. In the overall analysis, only progressive motility significantly improved after therapy. Subgroup analysis showed a significant increase in progressive motility, total motile sperm count (TMSC), and in the percentage of alive spermatozoa after treatment in the group A. Progressive motility improved significantly in patients with varicocele, while the TMSC in patients with varicocele and those with idiopathic infertility. The percentage of alive spermatozoa increased in patients with testicular hypotrophy.

CONCLUSIONS

Treatment with antioxidants increased progressive sperm motility, especially in patients with varicocele or idiopathic infertility.

The construction of a testis transcriptional cell atlas from embryo to adult reveals various somatic cells and their molecular roles

BACKGROUND

The testis is a complex organ that undergoes extensive developmental changes from the embryonic stage to adulthood. The development of germ cells, which give rise to spermatozoa, is tightly regulated by the surrounding somatic cells.

METHODS

To better understand the dynamics of these changes, we constructed a transcriptional cell atlas of the testis, integrating single-cell RNA sequencing data from over 26,000 cells across five developmental stages: fetal germ cells, infants, childhood, peri-puberty, and adults. We employed various analytical techniques, including clustering, cell type assignments, identification of differentially expressed genes, pseudotime analysis, weighted gene co-expression network analysis, and evaluation of paracrine cell-cell communication, to comprehensively analyze this transcriptional cell atlas of the testis.

RESULTS

Our analysis revealed remarkable heterogeneity in both somatic and germ cell populations, with the highest diversity observed in Sertoli and Myoid somatic cells, as well as in spermatogonia, spermatocyte, and spermatid germ cells. We also identified key somatic cell genes, including RPL39, RPL10, RPL13A, FTH1, RPS2, and RPL18A, which were highly influential in the weighted gene co-expression network of the testis transcriptional cell atlas and have been previously implicated in male infertility. Additionally, our analysis of paracrine cell-cell communication supported specific ligand-receptor interactions involved in neuroactive, cAMP, and estrogen signaling pathways, which support the crucial role of somatic cells in regulating germ cell development.

CONCLUSIONS

Overall, our transcriptional atlas provides a comprehensive view of the cell-to-cell heterogeneity in the testis and identifies key somatic cell genes and pathways that play a central role in male fertility across developmental stages.

Transcriptome Studies Reveal the N6-Methyladenosine Differences in Testis of Yaks at Juvenile and Sexual Maturity Stages

Studying the mechanism of spermatogenesis is key to exploring the reproductive characteristics of male yaks. Although N6-methyladenosine (m6A) RNA modification has been reported to regulate spermatogenesis and reproductive function in mammals, the molecular mechanism of m6A in yak testis development and spermatogenesis remains largely unknown. Therefore, we collected testicular tissue from juvenile and adult yaks and found that the m6A level significantly increased after sexual maturity in yaks. In MeRIP-seq, 1702 hypermethylated peaks and 724 hypomethylated peaks were identified. The hypermethylated differentially methylated RNAs (DMRs) (CIB2, AK1, FOXJ2, PKDREJ, SLC9A3, and TOPAZ1) mainly regulated spermatogenesis. Functional enrichment analysis showed that DMRs were significantly enriched in the adherens junction, gap junction, and Wnt, PI3K, and mTOR signaling pathways, regulating cell development, spermatogenesis, and testicular endocrine function. The functional analysis of differentially expressed genes showed that they were involved in the biological processes of mitosis, meiosis, and flagellated sperm motility during the sexual maturity of yak testis. We also screened the key regulatory factors of testis development and spermatogenesis by combined analysis, which included BRCA1, CREBBP, STAT3, and SMAD4. This study indexed the m6A characteristics of yak testicles at different developmental stages, providing basic data for further research of m6A modification regulating yak testicular development.

Biallelic variants in KCTD19 associated with male factor infertility and oligoasthenoteratozoospermia

STUDY QUESTION

Can whole-exome sequencing (WES) reveal new genetic factors responsible for male infertility characterized by oligozoospermia?

SUMMARY ANSWER

We identified biallelic missense variants in the Potassium Channel Tetramerization Domain Containing 19 gene (KCTD19) and confirmed it to be a novel pathogenic gene for male infertility.

WHAT IS KNOWN ALREADY

KCTD19 is a key transcriptional regulator that plays an indispensable role in male fertility by regulating meiotic progression. Kctd19 gene-disrupted male mice exhibit infertility due to meiotic arrest.

STUDY DESIGN, SIZE, DURATION

We recruited a cohort of 536 individuals with idiopathic oligozoospermia from 2014 to 2022 and focused on five infertile males from three unrelated families. Semen analysis data and ICSI outcomes were collected. WES and homozygosity mapping were performed to identify potential pathogenic variants. The pathogenicity of the identified variants was investigated in silico and in vitro.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Male patients diagnosed with primary infertility were recruited from the Reproductive and Genetic Hospital of CITIC-Xiangya. Genomic DNA extracted from affected individuals was used for WES and Sanger sequencing. Sperm phenotype, sperm nuclear maturity, chromosome aneuploidy, and sperm ultrastructure were assessed using hematoxylin and eosin staining and toluidine blue staining, FISH and transmission electron microscopy. The functional effects of the identified variants in HEK293T cells were investigated via western blotting and immunofluorescence.

MAIN RESULTS AND THE ROLE OF CHANCE

We identified three homozygous missense variants (NM_001100915, c.G628A:p.E210K, c.C893T:p.P298L, and c.G2309A:p.G770D) in KCTD19 in five infertile males from three unrelated families. Abnormal morphology of the sperm heads with immature nuclei and/or nuclear aneuploidy were frequently observed in individuals with biallelic KCTD19 variants, and ICSI was unable to rescue these deficiencies. These variants reduced the abundance of KCTD19 due to increased ubiquitination and impaired its nuclear colocalization with its functional partner, zinc finger protein 541 (ZFP541), in HEK293T cells.

LIMITATIONS, REASONS FOR CAUTION

The exact pathogenic mechanism remains unclear, and warrants further studies using knock-in mice that mimic the missense mutations found in individuals with biallelic KCTD19 variants.

WIDER IMPLICATIONS OF THE FINDINGS

Our study is the first to report a likely causal relationship between KCTD19 deficiency and male infertility, confirming the critical role of KCTD19 in human reproduction. Additionally, this study provided evidence for the poor ICSI clinical outcomes in individuals with biallelic KCTD19 variants, which may guide clinical treatment strategies.

STUDY FUNDING/COMPETING INTEREST(S)

This work was supported by the National Key Research and Developmental Program of China (2022YFC2702604 to Y.-Q.T.), the National Natural Science Foundation of China (81971447 and 82171608 to Y.-Q.T., 82101961 to C.T.), a key grant from the Prevention and Treatment of Birth Defects from Hunan Province (2019SK1012 to Y.-Q.T.), a Hunan Provincial Grant for Innovative Province Construction (2019SK4012), and the China Postdoctoral Science Foundation (2022M721124 to W.W.). The authors declare no conflicts of interest.

TRIAL REGISTRATION NUMBER

N/A.

The Renaissance of Male Infertility Management in the Golden Age of Andrology

Infertility affects nearly 186 million people worldwide and the male partner is the cause in about half of the cases. Meta-regression data indicate an unexplained decline in sperm concentration and total sperm count over the last four decades, with an increasing prevalence of male infertility. This suggests an urgent need to implement further basic and clinical research in Andrology. Andrology developed as a branch of urology, gynecology, endocrinology, and, dermatology. The first scientific journal devoted to andrological sciences was founded in 1969. Since then, despite great advancements, andrology has encountered several obstacles in its growth. In fact, for cultural reasons, the male partner has often been neglected in the diagnostic and therapeutic workup of the infertile couple. Furthermore, the development of assisted reproductive techniques (ART) has driven a strong impression that this biotechnology can overcome all forms of infertility, with a common belief that having a spermatozoon from a male partner (a sort of sperm donor) is all that is needed to achieve pregnancy. However, clinical practice has shown that the quality of the male gamete is important for a successful ART outcome. Furthermore, the safety of ART has been questioned because of the high prevalence of comorbidities in the offspring of ART conceptions compared to spontaneous conceptions. These issues have paved the way for more research and a greater understanding of the mechanisms of spermatogenesis and male infertility. Consequently, numerous discoveries have been made in the field of andrology, ranging from genetics to several "omics" technologies, oxidative stress and sperm DNA fragmentation, the sixth edition of the WHO manual, artificial intelligence, management of azoospermia, fertility in cancers survivors, artificial testis, 3D printing, gene engineering, stem cells therapy for spermatogenesis, and reconstructive microsurgery and seminal microbiome. Nevertheless, as many cases of male infertility remain idiopathic, further studies are required to improve the clinical management of infertile males. A multidisciplinary strategy involving both clinicians and scientists in basic, translational, and clinical research is the core principle that will allow andrology to overcome its limits and reach further goals. This state-of-the-art article aims to present a historical review of andrology, and, particularly, male infertility, from its "Middle Ages" to its "Renaissance", a golden age of andrology.

Analysis of 29 Targeted Genes for Non-Obstructive Azoospermia: The Relationship between Genetic Testing and Testicular Histology

PURPOSE

To analyze the presence of potentially pathogenic variants of 29 candidate genes known to cause spermatogenic failure (SPGF) in patients with non-obstructive azoospermia (NOA) who underwent testicular histology.

MATERIALS AND METHODS

Forty-eight patients with unexplained NOA referred to the Department of Transfusion Medicine and Transplantation Biology, University Hospital Center Zagreb, Zagreb, Croatia for testicular biopsy. They were divided into three groups: those who had cryptorchidism (n=9), those with varicocele (n=14), and those with idiopathic NOA (n=25). All included patients underwent blood withdrawal for next-generation sequencing (NGS) analysis and gene sequencing.

RESULTS

We found a possible genetic cause in 4 patients with idiopathic NOA (16%) and in 2 with cryptorchidism (22%). No pathogenic or possibly pathogenic mutations were identified in patients with varicocele. Variants of undetermined significance (VUS) were found in 11 patients with idiopathic NOA (44%), 3 with cryptorchidism (33%), and 8 patients with varicocele (57%). VUSs of the USP9Y gene were the most frequently as they were found in 14 out of 48 patients (29%). In particular, the VUS USP9Y c.7434+14del was found in 11 patients. They showed varied histological pictures, including Sertoli cell-only syndrome, mixed atrophy, and hypospermatogenesis, regardless of cryptorchidism or varicocele. No direct correlation was found between the gene mutation/variant and the testicular histological picture.

CONCLUSIONS

Different mutations of the same gene cause various testicular histological pictures. These results suggest that it is not the gene itself but the type of mutation/variation that determines the testicular histology picture. Based on the data presented above, it remains challenging to design a genetic panel with prognostic value for the outcome of testicular sperm extraction in patients with NOA.

NECL2 regulates blood-testis barrier dynamics in mouse testes

The adhesion protein nectin-like molecule 2 (NECL2) is involved in spermatogenesis and participates in the connections between Sertoli cells and germ cells. Necl2 deficiency leads to infertility in male mice. We found that NECL2 is relatively highly expressed on the cell membranes of preleptotene spermatocytes. It is known that preleptotene spermatocytes pass through the blood-testis barrier (BTB) from the base of the seminiferous tubules to the lumen to complete meiosis. We hypothesized that the NECL2 protein on the surfaces of preleptotene spermatocytes has an effect on the BTB when crossing the barrier. Our results showed that Necl2 deficiency caused the levels of proteins in the BTB to be abnormal, such as those of Claudin 3, claudin 11, and Connexin43. NECL2 interacted and colocalized with adhesion proteins forming the BTB, such as Connexin43, Occludin, and N-cadherin. NECL2 regulated BTB dynamics when preleptotene spermatocytes passed through the barrier, and Necl2 deficiency caused BTB damage. Necl2 deletion significantly affected the testicular transcriptome, especially the expression of spermatogenesis-related genes. These results suggest that before meiosis and spermatid development occur, BTB dynamics regulated by NECL2 are necessary for spermatogenesis.

Temporal decline of sperm concentration: role of endocrine disruptors

INTRODUCTION

Male infertility is a widespread disease with an etiology that is not always clear. A number of studies have reported a decrease in sperm production in the last forty years. Although the reasons are still undefined, the change in environmental conditions and the higher exposure to endocrine-disrupting chemicals (EDCs), namely bisphenol A, phthalates, polychlorinated biphenyls, polybrominated diphenyl esters, dichlorodiphenyl-dichloroethylene, pesticides, and herbicides, organophosphates, and heavy metals, starting from prenatal life may represent a possible factor justifying the temporal decline in sperm count.

AIM

The aim of this study is to provide a comprehensive description of the effects of the exposure to EDCs on testicular development, spermatogenesis, the prevalence of malformations of the male genital tract (cryptorchidism, testicular dysgenesis, and hypospadias), testicular tumor, and the mechanisms of testicular EDC-mediated damage.

NARRATIVE REVIEW

Animal studies confirm the deleterious impact of EDCs on the male reproductive apparatus. EDCs can compromise male fertility by binding to hormone receptors, dysregulating the expression of receptors, disrupting steroidogenesis and hormonal metabolism, and altering the epigenetic mechanisms. In humans, exposure to EDCs has been associated with poor semen quality, increased sperm DNA fragmentation, increased gonadotropin levels, a slightly increased risk of structural abnormalities of the genital apparatus, such as cryptorchidism and hypospadias, and development of testicular tumor. Finally, maternal exposure to EDCs seems to predispose to the risk of developing testicular tumors.

CONCLUSION

EDCs negatively impact the testicular function, as suggested by evidence in both experimental animals and humans. A prenatal and postnatal increase to EDC exposure compared to the past may likely represent one of the factors leading to the temporal decline in sperm counts.

Contribution of TEX15 genetic variants to the risk of developing severe non-obstructive oligozoospermia

Background: Severe spermatogenic failure (SPGF) represents one of the most relevant causes of male infertility. This pathological condition can lead to extreme abnormalities in the seminal sperm count, such as severe oligozoospermia (SO) or non-obstructive azoospermia (NOA). Most cases of SPGF have an unknown aetiology, and it is known that this idiopathic form of male infertility represents a complex condition. In this study, we aimed to evaluate whether common genetic variation in TEX15, which encodes a key player in spermatogenesis, is involved in the susceptibility to idiopathic SPGF. Materials and Methods: We designed a genetic association study comprising a total of 727 SPGF cases (including 527 NOA and 200 SO) and 1,058 unaffected men from the Iberian Peninsula. Following a tagging strategy, three tag single-nucleotide polymorphisms (SNPs) of TEX15 (rs1362912, rs323342, and rs323346) were selected for genotyping using TaqMan probes. Case-control association tests were then performed by logistic regression models. In silico analyses were also carried out to shed light into the putative functional implications of the studied variants. Results: A significant increase in TEX15-rs1362912 minor allele frequency (MAF) was observed in the group of SO patients (MAF = 0.0842) compared to either the control cohort (MAF = 0.0468, OR = 1.90, p = 7.47E-03) or the NOA group (MAF = 0.0472, OR = 1.83, p = 1.23E-02). The genotype distribution of the SO population was also different from those of both control (p = 1.14E-02) and NOA groups (p = 4.33-02). The analysis of functional annotations of the human genome suggested that the effect of the SO-associated TEX15 variants is likely exerted by alteration of the binding affinity of crucial transcription factors for spermatogenesis. Conclusion: Our results suggest that common variation in TEX15 is involved in the genetic predisposition to SO, thus supporting the notion of idiopathic SPGF as a complex trait.

Compound heterozygous mutations in PMFBP1 cause acephalic spermatozoa syndrome: A case report

BACKGROUND

Acephalic spermatozoa syndrome (ASS) is an extremely rare form of severe teratozoospermia, where in most of the sperm either appear to lack heads or have disconnected or poorly connected heads and tails.

CASE SUMMARY

We reported the case of a male patient with secondary infertility whose sperm showed typical ASS upon morphological analysis. Whole-exome sequencing was performed on the patient’s peripheral blood, which revealed two heterozygous variants of the PMFBP1 gene: PMFBP1c.414+1G>T (p.?) and PMFBP1c.393del (p.C132Afs*3).

CONCLUSION

It is speculated that the compound homozygous mutation of PMFBP1 may be the cause of ASS. We conducted a literature review in order to provide the basis for genetic counseling and clinical diagnosis of patients with ASS.

Homeodomain-interacting protein kinase HIPK4 regulates phosphorylation of manchette protein RIMBP3 during spermiogenesis

Nonobstructive azoospermia (NOA) is the most serious form of spermatogenesis abnormalities in male infertility. Genetic factors are important to consider as elements leading to NOA. Although many pathogenic genes have been reported, the causative genes of NOA for many patients are still unknown. In this study, we found ten point mutations in the gene encoding homeodomain-interacting protein kinase 4 (HIPK4) in patients with NOA, and using in vitro studies, we determined a premature termination point mutation (p. Lys490∗, c.1468A>T) that can cause decreased expression of HIPK4. Our phosphoproteomic analysis of Hipk4^−/− testes revealed phosphorylation of multiple proteins regulated by HIPK4 during spermiogenesis. We also confirmed that a substrate of HIPK4 with four downregulated phosphorylation sites matching the xSPx motif is the known manchette-related protein RIMS-binding protein 3, which is required for sperm head morphogenesis. Therefore, we conclude HIPK4 regulates the phosphorylation of manchette protein RIMS-binding protein 3 and plays essential roles in sperm head shaping and male fertility.

Human obstructive (postvasectomy) and nonobstructive azoospermia - Insights from scRNA-Seq and transcriptome analysis

A substantial number of male infertility is caused by azoospermia. However, the underlying etiology and the molecular basis remain largely unknown. Through single-cell (sc)RNA sequencing, we had analyzed testis biopsy samples from two patients with obstructive azoospermia (OA) and nonobstructive azoospermia (NOA). We found only somatic cells in the NOA samples and explored the transcriptional changes in Sertoli cells in response to a loss of interactions with germ cells. Moreover, we observed a germ cell population discrepancy between an OA (postvasectomy) patient and a healthy individual. We confirmed this observation in a secondary study with two datasets at GSM3526588 and GSE124263 for detailed analysis wherein the regulatory mechanisms at the transcriptional level were identified. These findings thus provide valuable information on human spermatogenesis, and we also identified insightful information for further research on reproduction-related diseases.

Association of CATSPER1, SPATA16 and TEX11 genes polymorphism with idiopathic azoospermia and oligospermia risk in Iranian population

Background

Male infertility is a heterogeneous disease which can occur due to spermatogenesis defects. The idiopathic azoospermia and oligospermia are the common cause of male infertility with unknown underlying molecular mechanisms. The aim of this study was to investigate association of idiopathic azoospermia and oligospermia with single-nucleotide polymorphisms of CATSPER1, SPATA16 and TEX11 genes in Iranian-Azeri men.

Methods

In this case–control study, we recruited 100 infertile men (case group) and 100 fertile men (control group) from Azeri population in north western provinces, Iran, population. The genomic DNA was extracted using a proteinase K method from peripheral blood leukocytes. The genotypes analysis was conducted using tetra-primer amplification refractory mutation system-polymerase chain reaction method. The obtained data were analyzed by statistical software.

Results

We found a significant difference in the frequencies of heterozygote AB and mutant homozygote BB genotypes in the CATSPER1 (rs2845570) gene polymorphism between patients and healthy controls (p < 0.05). Moreover, we observed a significant difference in the frequencies of heterozygote BA genotype in the SPATA16 (rs1515442) gene polymorphism between patients and healthy controls (p < 0.05). However, no significant difference was found in genotypes distribution of case and control groups in the TEX11 (rs143246552) gene polymorphism.

Conclusion

Our finding showed that the CATSPER1 (rs2845570) and SPATA16 (rs1515442) genes polymorphism may play an important role in idiopathic azoospermia and oligospermia in Iranian Azeri population. However, more extensive studies with larger sample sizes from different ethnic origins are essential for access more accurate results.

The I510V mutation in KLHL10 in a patient with oligoasthenoteratozoospermia

Oligoasthenoteratozoospermia is a human infertility syndrome caused by defects in spermatogenesis, spermiogenesis, and sperm maturation, and its etiology remains unclear. Kelch-like 10 (KLHL10) is a component of ubiquitin ligase E3 10 (KLHL10) and plays an important role in male fertility. Deletion or mutation of the Klhl10 gene in Drosophila or mice results in defects in spermatogenesis or sperm maturation. However, the molecular mechanisms by which KLHL10 functions remain elusive. In this study, we identified a missense mutation (c.1528A→G, p.I510V) in exon 5 of KLHL10, which is associated with oligoasthenoteratozoospermia in humans. To investigate the effects of this mutation on KLHL10 function and spermatogenesis and/or spermiogenesis, we generated mutant mice duplicating the amino acid conversion using the clustered regularly interspaced palindromic repeat/caspase 9 (CRISPR/Cas9) system and designated them Klhl10^I510V mice. However, the Klhl10^I510V mice did not exhibit any defects in testis development, spermatogenesis, or sperm motility at ten-weeks-of-age, suggesting that this mutation does not disrupt the KLHL10 function, and may not be the cause of male infertility in the affected individual with oligoasthenoteratozoospermia.

Reciprocal translocation and Robertsonian translocation in relation to semen parameters: A retrospective study and systematic review

Reciprocal translocation and Robertsonian translocation are known to be causative factors of male infertility. However, the association between autosomal reciprocal translocation, Robertsonian translocation and semen parameters remains controversial. We performed a retrospective study and systematic review to investigate semen parameters in patients with autosomal reciprocal translocation or Robertsonian translocation. We recruited a total of 1,033 controls, 723 reciprocal translocation carriers and 326 Robertsonian translocation carriers. Men in the control, reciprocal translocation and Robertsonian translocation groups had a median age of 32.0 (95% CI, 32.0-33.0), 32.0 (95% CI, 32.0-33.0) and 33.0 (95% CI, 32.0-33.0) years respectively. Results showed that sperm concentration, total number per ejaculate, total motility, progressive motility of autosomal reciprocal translocation and Robertsonian translocation carriers were statistically lower than controls (p < .001). Eleven studies featuring 794 patients were enrolled in this systematic review. Compared with controls, autosomal reciprocal translocation and Robertsonian translocation carriers showed lower sperm concentration, total motility, progressive motility and normal morphology. Our results support the conclusion that sperm concentration, total number per ejaculate, total motility and progressive motility are significantly lower in autosomal reciprocal translocation and Robertsonian translocation carriers than in controls.

A homozygous loss-of-function mutation in FBXO43 causes human non-obstructive azoospermia

Non-obstructive azoospermia (NOA) represents one of the most serious forms of male infertility caused by spermatogenic failure. Despite multiple genes found to be associated with human NOA, the genetic basis of this idiopathic disease remains largely unknown. FBXO43 is a direct inhibitor of the anaphase-promoting complex/cyclosome (APC/C) E3 ligase and crucially important in mouse spermatogenesis. In this study, for the first time, we identified a homozygous nonsense mutation in FBXO43 c.1747C > T:p.Gln583X in two NOA brothers from a Chinese consanguineous family via whole-exome sequencing. FBXO43 was absent from testicular tissue of the proband, and FBXO43-immunostaining signals were invisible in the affected seminiferous tubules. Furthermore, in humans, FBXO43 defects cause meiotic arrest within early diplotene of prophase I. The results here demonstrate the pathogenicity of this loss-of-function mutation and confirmed that spermatocytes were unable to complete meiotic divisions without FBXO43 in humans. In mouse testicular protein extracts, three subunits of the APC/C, including ANAPC2, ANAPC8 and ANAPC10, were validated to interact directly with FBXO43, whereas no interactions were detected for FBXO43 and SKP1. This study furthers our understanding of the genetic basis of human NOA and provides insights into FBXO43 and male infertility.

The SEPT12 complex is required for the establishment of a functional sperm head-tail junction

The connecting pieces of the sperm neck link the flagellum and the sperm head, and they are important for initiating flagellar beating. The connecting pieces are important building blocks for the sperm neck; however, the mechanism of connecting piece assembly is poorly understood. In the present study, we explored the role of septins in sperm motility and found that Sept12D197N knock-in (KI) mice produce acephalic and immotile spermatozoa. Electron microscopy analysis showed defective connecting pieces in sperm from KI mice, indicating that SEPT12 is required for the establishment of connecting pieces. We also found that SEPT12 formed a complex with SEPT1, SEPT2, SEPT10 and SEPT11 at the sperm neck and that the D197N mutation disrupted the complex, suggesting that the SEPT12 complex is involved in the assembly of connecting pieces. Additionally, we found that SEPT12 interacted and colocalized with γ-tubulin in elongating spermatids, implying that SEPT12 and pericentriolar materials jointly contribute to the formation of connecting pieces. Collectively, our findings suggest that SEPT12 is required for the formation of striated columns, and the capitulum and for maintaining the stability of the sperm head-tail junction.

An NGS-based approach to identify Y-chromosome variation in non-obstructive azoospermia

Copy number variations (CNVs), including deletions and duplications on the Y chromosome, are known genetic factors in azoospermia. Therefore, it is important to identify novel pathogenic CNVs related to azoospermia. In this study, we compared CNVs detected by STS-PCR and NGS in 107 individuals with nonobstructive azoospermia (NOA). STS-PCR analysis revealed that 8.14% (9/107) of patients had AZF deletions. The highest percentage of deletions was located in the AZFc region, followed by AZFa and AZFb+c. Positive CNVs, including four duplications, six deletions and three complex CNVs, were detected using NGS methods in 12.15% (13/107) of NOA patients. Both the duplications and deletions detected in q11.223 were confirmed to increase the genetic risk for NOA. A comparison between the STS-PCR results and NGS methods revealed concordant CNV-positive results in 4 of 107 cases (3.74%). The discrepancies included 6 cases with CNVs identified by NGS but not detected by STS-PCR, and two cases were detected by STS-PCR but not by NGS. Notably, four duplications were not identified and three complex CNVs were detected as simple deletions using STS-PCR analysis. The NGS method provides comprehensive results in detecting Y chromosome-linked CNVs, including deletions and duplications, which might broaden our understanding of NOA.

Targeted next-generation sequencing panel screening of 668 Chinese patients with non-obstructive azoospermia

PURPOSE

We aimed (1) to determine the molecular diagnosis rate and the recurrent causative genes of patients with non-obstructive azoospermia (NOA) using targeted next-generation sequencing (NGS) panel screening and (2) to discuss whether these genes help in the prognosis for microsurgical testicular sperm extraction (micro-TESE).

METHODS

We used NGS panels to screen 668 Chinese men with NOA. Micro-TESE outcomes for six patients with pathogenic mutations were followed up. Functional assays were performed for two NR5A1 variants identified: p.I224V and p.R281C.

RESULTS

Targeted NGS panel sequencing could explain 4/189 (2.1% by panel 1) or 10/479 (2.1% by panel 2) of the patients with NOA after exclusion of karyotype abnormalities and Y chromosome microdeletions. Almost all mutations detected were newly described except for NR5A1 p.R281C and TEX11 p.M156V. Two missense NR5A1 mutations-p.R281C and p.I244V-were proved to be deleterious by in vitro functional assays. Mutations in TEX11, TEX14, and NR5A1 genes are recurrent causes of NOA, but each gene explains only a very small percentage (less than 4/668; 0.6%). Only the patient with NR5A1 mutations produced viable spermatozoa through micro-TESE, but other patients with TEX11 and TEX14 had poor micro-TESE prognoses.

CONCLUSIONS

A targeted NGS panel is a feasible diagnostic method for patients with NOA. Because each gene implicated explains only a small proportion of such cases, more genes should be included to further increase the diagnostic rate. Considering previous reports, we suggest that only a few genes that are directly linked to meiosis can indicate poor micro-TESE prognosis, such as TEX11, TEX14, and SYCE1.

Leukocytospermia in late adolescents: possible clinical interpretations

BACKGROUND

No data are currently available on the implication of amicrobial leukocytospermia in male adolescents. Therefore, the primary aim of this study was to evaluate the prevalence of amicrobial leukocytospermia among non-smoker late adolescents who were exposed to other risky lifestyles for the andrological health. The main andrological clinical features of adolescents with leukocytospermia were also reported.

METHODS

This is a cross-sectional study carried out in 80 boys. Each adolescent underwent a physical examination, and to the assessment of sperm conventional parameters, seminal leukocytes concentration and immature germ cell evaluation. A possible correlation between seminal leukocytes and immature germ cells and testicular volume (TV) was tested.

RESULTS

The adolescents enrolled in this study had 18.0 ± 0.4 (range 18.1-18.9) years. Unprotected sexual intercourse was referred by 38% of them. Sexual dysfunctions were found in 25% and isolated hypoactive sexual desire in 12.5% of boys. Low TV and penile length in flaccidity were found in 44% and 30% of them, respectively. Only 41% had normozoospermia at the sperm analysis, whereas 19% had isolated oligozoospermia, 15% oligo-asthenozoospermia, and 25% oligo-astheno-teratozoospermia. Leukocytospermia occurred in 25% (20 out of 80) of adolescents. No seminal infection was detected in 19% (15 out of 80) of them. Adolescents with leukocytospermia had lower progressive sperm motility, percentage of normal forms, TV, and a higher percentage of immature germ cells compared to those without leukocytospermia. Semen leukocyte concentration correlated negatively with TV and positively with the percentage of immature germ cells in the ejaculate.

CONCLUSION

Leukocytospermia, increased immature germ cell number, and low TV identify a distinct phenotype suggestive of testicular tubulopathy. Primary prevention of male infertility and the counselling for andrological risky lifestyles is mandatory and should be started as early as possible.

HAART exacerbates testicular damage and impaired spermatogenesis in anti-Koch-treated rats via dysregulation of lactate transport and glutathione content

Highly active anti-retroviral therapy (HAART) is an effective anti-retroviral cocktail. Similarly, anti-Koch is highly potent against Mycobacterium tuberculosis. However, these drugs have been shown to impair male fertility. This study investigated the impact of HAART and anti-Koch, when used alone and co-administered, on testicular and sperm integrity. Thirty-two adult male Wistar rats were assigned randomly into four groups (n = 8), namely normal control, HAART-treated, anti-Koch-treated, and HAART + anti-Koch-treated. The doses of drugs were the human equivalent doses for rats. Administration was once daily per os and lasted for eight weeks. HAART aggravated anti-Koch-induced reduction in testicular and penile weights. In addition, anti-Koch also led to a distortion of testicular cytoarchitecture, disturbed spermatogenesis, and caused low sperm quality, including sperm dysmotility. More so, anti-Koch led to a significant elevation of uric acid and dysregulation of testicular lactate transport and glutathione content. These events were accompanied by enhanced lipid peroxidation and inflammation of the testicular tissue and reduced testicular and sperm DNA integrity. These adverse effects of anti-Koch were aggravated by co-administration of HAART. Thus, our results infer that HAART exacerbates anti-Koch-induced impairment of spermatogenesis and testicular and sperm toxicity through up-regulation of uric acid generation and dysregulation of lactate transport and glutathione system.

Testis developmental related gene 1 (TDRG1) encodes a progressive motility-associated protein in human spermatozoa

STUDY QUESTION

Is there an association between the human testis-specific gene, testis developmental related gene 1 (TDRG1) and human sperm motility?

SUMMARY ANSWER

TDRG1 is associated with asthenozoospermia and involved in regulating human sperm motility.

WHAT IS KNOWN ALREADY

Many testis-specific proteins potentially regulate spermatogenesis and sperm motility. We have identified a novel human testis-specific gene, TDRG1, which encodes a 100-amino-acid protein localized in the human sperm tail, yet little is known about its role in human spermatozoa.

STUDY DESIGN, SIZE, DURATION

Sperm samples were obtained from normozoospermic men and asthenozoospermic men who visited the reproductive medical center at Jiangxi Maternal and Child Health Hospital, Nanchang, Jiangxi, China between February 2018 and January 2019. In total, 27 normozoospermic men and 25 asthenozoospermic men were recruited to participate in the study.

PARTICIPANTS/MATERIALS, SETTING, METHODS

The level of TDRG1 in sperm of normozoospermic and asthenozoospermic men was examined by immunoblotting and immunofluorescence assays. Progressive motility was examined by computer-aided sperm analysis. The correlation between the TDRG1 protein level and progressive motility was analyzed by linear regression. TDRG1 was imported into the sperm of normozoospermic and asthenozoospermic men using a cell-penetrating peptide (CPP)-fused TDRG1 recombinant protein (CPP-TDRG1), and the progressive motility was examined. Also, the altered proteins associated with TDRG1 in asthenozoospermic sperm were detected using label-free quantification method-based quantitative proteomic technology. TDRG1-interacting proteins were identified by co-immunoprecipitation coupled with tandem mass spectrometry analysis.

MAIN RESULTS AND THE ROLE OF CHANCE

The mean level of TDRG1 was significantly decreased in sperm of asthenozoospermic men compared with normozoospermic men (P < 0.05) and was positively correlated with percentage of progressively motile sperm (r2 = 0.75, P = 0.0001). The introduction of TDRG1 into human sperm, using CPP, significantly increased progressive motility (P < 0.05) and improved the progressive motility of sperm from asthenozoospermic men to the normal level. TDRG1 forms a protein complex with sperm-motility related proteins in human sperm and its downregulation was associated with a decrease in other motility-related proteins.

LARGE SCALE DATA

N/A.

LIMITATIONS, REASONS FOR CAUTION

The sample size was limited and larger cohorts are needed for verifying the positive effect of CPP-TDRG1 on human sperm motility. Furthermore, the caution should be paid that a comprehensive safety examination would be performed to evaluate whether CPP-TDRG1 is a possible treatment approach for asthenozoospermia.

WIDER IMPLICATIONS OF THE FINDINGS

Our results provide new insights into the mechanisms of sperm motility which may contribute to the diagnosis and treatment for asthenozoospermia.

STUDY FUNDING/COMPETING INTEREST(S)

National Natural Science Foundation of China (81501317 and 81871207 to H.C.; 81771644 to T.L.; 31671204 to X.Z.; 81571432 to Y.T.). The authors have no conflicts of interest to declare.

A simultaneous next-generation sequencing approach to the diagnosis of couple infertility

BACKGROUND

Infertility is a disorder of the male and/or female reproductive system, characterized by failure to establish a clinical pregnancy after 12 months of regular unprotected sexual intercourse. On a world basis, about one in six couplesare affected by infertility during their reproductive lifespan. Despite a comprehensive diagnostic work-up, infertility in about 50% of couples remains idiopathic. In this context, a next-generation sequencing (NGS) approach has been suggested to increase diagnostic yield. Accordingly, this study aimed to evaluate the effectiveness of a custom-made NGS gene panel for the simultaneous genetic diagnosis of both partners of a large population of infertile couples.

METHODS

We developed a custom-made NGS panel for 229 genes associated with male and female infertility. The panel targeted exons and their flanking regions and was used to screen 99 couples with idiopathic infertility.

RESULTS

NGS sequencing revealed five pathogenic variants in six couples and 17 likely pathogenic variants or variants with uncertain significance (VUS). The pathogenic variants were identified in the following genes: GNRHR, CCDC39, DNAH5, and CCDC103; likely pathogenic variants were identified in TAC3, PROKR2, and CFTR; VUS were identified in CATSPER2, FGFR1, LRRC6, DNAH5, DNAH11, TGFBR3, and DNAI1.

CONCLUSIONS

The panel of genes designed for this study allowed the identification of pathogenetic gene mutations and the presence of VUS in 6.1% and 17.2%, respectively, of couples with idiopathic infertility. This is the first study to successfully apply an NGS-based genetic screening including 229 genes known to play a role in both male and female infertility.

Human testis-expressed (TEX) genes: a review focused on spermatogenesis and male fertility

Spermatogenesis is a complex process regulated by a multitude of genes. The identification and characterization of male-germ-cell-specific genes is crucial to understanding the mechanisms through which the cells develop. The term “TEX gene” was coined by Wang et al. (Nat Genet. 2001; 27: 422–6) after they used cDNA suppression subtractive hybridization (SSH) to identify new transcripts that were present only in purified mouse spermatogonia. TEX (Testis expressed) orthologues have been found in other vertebrates (mammals, birds, and reptiles), invertebrates, and yeasts. To date, 69 TEX genes have been described in different species and different tissues. To evaluate the expression of each TEX/tex gene, we compiled data from 7 different RNA-Seq mRNA databases in humans, and 4 in the mouse according to the expression atlas database.

Various studies have highlighted a role for many of these genes in spermatogenesis. Here, we review current knowledge on the TEX genes and their roles in spermatogenesis and fertilization in humans and, comparatively, in other species (notably the mouse). As expected, TEX genes appear to have a major role in reproduction in general and in spermatogenesis in humans but also in all mammals such as the mouse. Most of them are expressed specifically or predominantly in the testis. As most of the TEX genes are highly conserved in mammals, defects in the male (gene mutations in humans and gene-null mice) lead to infertility. In the future, cumulative data on the human TEX genes’ physiological functions and pathophysiological dysfunctions should become available and is likely to confirm the essential role of this family in the reproductive process. Thirteen TEX genes are now referenced in the OMIM database, and 3 have been linked to a specific phenotype. TEX11 (on Xq13.1) is currently the gene most frequently reported as being associated with azoospermia.

Expression of the Testis-Specific Serine/Threonine Kinases Suggests Their Role in Spermiogenesis of Bay Scallop Argopecten irradians

Members of the testis-specific serine/threonine kinases (Tssk) family play critical roles in spermatogenesis in vertebrates. But in mollusks, research on Tssk family is still lagging. In this study, we systematically identified Tssk family based on the genomic and transcriptomic data from a commercially important scallop Argopecten irradians and detected the spatiotemporal expression in adult gonads. Five members were identified, with the gene length varying from 1,068 to 10,729 bp and the protein length ranging from 294 to 731 aa. All the Tssks possess a serine/threonine protein kinase catalytic (S_TKc) domain. Phylogenetic analysis revealed existence of four homologs of vertebrate Tssk1/2, Tssk3, Tssk4, Tssk5, and absence of Tssk6 in the scallop. The remaining gene (Tssk7) formed an independent clade with Tssks of other mollusks and arthropods, indicating that it may be a new member of Tssk family unique to protostomes. By investigating the expression of Tssks in four developmental stages of testes and ovaries, we found all five Tssks were primarily expressed in mature testis. In situ hybridization experiment revealed the five Tssks were localized in the spermatids and spermatozoa. The testis-predominant expression of Tssk family suggests Tssks may play pivotal roles in spermiogenesis in the scallop. Our study provides basic information on the characteristics and expression profiles of Tssk family of A. irradians. To our knowledge, it represents the first comprehensive analysis of Tssk family in mollusks.

CFTR gene variants as a reason for impaired spermatogenesis: a pilot study and a Meta-analysis of published data

There is increasing data that IVS8-5T variand and TG repeats could lead to impaired spermatogenesis. To investigate this we performed Sanger sequencing on 50 Bulgarian men with a sperm count below 5 × 10⁶/mL and 20 normal fertile men. Frequencies of the results were compared among the two groups. A meta-analysis was perfomed by using the data for 6,423 patients and 5,834 control subjects, tested for the IVS8-5T polymorphism. One case subject (2.0%) was homozygote for the 5 T/5T variant whereas two (4.0%) were heterozygotes for the 5 T/7T variant. No 5 T alleles were found in the control group. The genotypes of the two groups showed a statistically significant difference (p = 0.04, α < 0.05). Also, the odds ratio was 3.73, but this was unsignificant (p = 0.38). All control subjects had 11 TG repeats and for the test group: 47 (94.0%) men with 11 TG repeats and three (6.00%) with 10 TG repeats. Fisher's test showed no significant difference (p = 0.55). The meta-analysis showed that IVS8-5T variant was a risk factor for impaired spermatogenesis (OR = 2.84, p < 0.05) and this was more prominent for non-European (OR = 4.50, p < 0.05) compared to European (OR = 1.28, p < 0.05) men. The IVS8 - 5 T variant could be associated with disorders of sperm production.

Palindromes in DNA-A Risk for Genome Stability and Implications in Cancer

A palindrome in DNA consists of two closely spaced or adjacent inverted repeats. Certain palindromes have important biological functions as parts of various cis-acting elements and protein binding sites. However, many palindromes are known as fragile sites in the genome, sites prone to chromosome breakage which can lead to various genetic rearrangements or even cell death. The ability of certain palindromes to initiate genetic recombination lies in their ability to form secondary structures in DNA which can cause replication stalling and double-strand breaks. Given their recombinogenic nature, it is not surprising that palindromes in the human genome are involved in genetic rearrangements in cancer cells as well as other known recurrent translocations and deletions associated with certain syndromes in humans. Here, we bring an overview of current understanding and knowledge on molecular mechanisms of palindrome recombinogenicity and discuss possible implications of DNA palindromes in carcinogenesis. Furthermore, we overview the data on known palindromic sequences in the human genome and efforts to estimate their number and distribution, as well as underlying mechanisms of genetic rearrangements specific palindromic sequences cause.

Genetic basis of acephalic spermatozoa syndrome, and intracytoplasmic sperm injection outcomes in infertile men: a systematic scoping review

PURPOSE

Acephalic spermatozoa syndrome (ASS) is known as a severe type of teratozoospermia, defined as semen composed of mostly headless spermatozoa that affect male fertility. In this regard, this systematic review aimed to discuss gene variants associated with acephalic spermatozoa phenotype as well as the clinical outcomes of intracytoplasmic sperm injection (ICSI) treatment for the acephalic spermatozoa-associated male infertility.

METHODS

A systematic search was performed on PubMed, Embase, Scopus, and Ovid databases until May 17, 2020. This systematic scoping review was reported in terms of the Preferred Reporting Items for Systematic reviews and Meta-Analyses extension for Scoping Reviews (PRISMA-ScR) statement.

RESULTS

Twenty articles were included in this systematic review. Whole-exome and Sanger sequencing have helped in the identification of variants in SUN5, PMFBP1, BRDT, TSGA10, DNAH6, HOOK1, and CEP112 genes as possible causes of this phenotype in humans. The results of the ICSI are conflicting due to both positive and negative reports of ICSI outcomes.

CONCLUSION

ASS has a genetic origin, and several genetic alterations related to the pathogenesis of this anomaly have been recently identified. Notably, only SUN5 and PMFBP1 mutations are well-known to be implicated in ASS. Accordingly, more functional studies are needed to confirm the pathogenicity of other variants. ICSI could provide a promising treatment for acephalic spermatozoa-associated male infertility. Besides the importance of sperm head-tail junction integrity, some other factors, whether within the sperm cell or female factors, may be involved in the ICSI outcome.

Next-generation sequencing: toward an increase in the diagnostic yield in patients with apparently idiopathic spermatogenic failure

A large proportion of patients with idiopathic spermatogenic failure (SPGF; oligozoospermia or nonobstructive azoospermia [NOA]) do not receive a diagnosis despite an extensive diagnostic workup. Recent evidence has shown that the etiology remains undefined in up to 75% of these patients. A number of genes involved in germ-cell proliferation, spermatocyte meiotic divisions, and spermatid development have been called into play in the pathogenesis of idiopathic oligozoospermia or NOA. However, this evidence mainly comes from case reports. Therefore, this study was undertaken to identify the molecular causes of SPGF. To accomplish this, 15 genes (USP9Y, NR5A1, KLHL10, ZMYND15, PLK4, TEX15, TEX11, MEIOB, SOHLH1, HSF2, SYCP3, TAF4B, NANOS1, SYCE1, and RHOXF2) involved in idiopathic SPGF were simultaneously analyzed in a cohort of 25 patients with idiopathic oligozoospermia or NOA, accurately selected after a thorough diagnostic workup. After next-generation sequencing (NGS) analysis, we identified the presence of rare variants in the NR5A1 and TEX11 genes with a pathogenic role in 3/25 (12.0%) patients. Seventeen other different variants were identified, and among them, 13 have never been reported before. Eleven out of 17 variants were likely pathogenic and deserve functional or segregation studies. The genes most frequently mutated were MEIOB, followed by USP9Y, KLHL10, NR5A1, and SOHLH1. No alterations were found in the SYCP3, TAF4B, NANOS1, SYCE1, or RHOXF2 genes. In conclusion, NGS technology, by screening a specific custom-made panel of genes, could help increase the diagnostic rate in patients with idiopathic oligozoospermia or NOA.

SOX13 gene downregulation in peripheral blood mononuclear cells of patients with Klinefelter syndrome

Klinefelter syndrome (KS) is the most common sex chromosome disorder in men. It is characterized by germ cell loss and other variable clinical features, including autoimmunity. The sex-determining region of Y (SRY)-box 13 (Sox13) gene is expressed in mouse spermatogonia. In addition, it has been identified as islet cell autoantigen 12 (ICA12), which is involved in the pathogenesis of autoimmune diseases, including type 1 diabetes mellitus (DM) and primary biliary cirrhosis. Sox13 expression has never been investigated in patients with KS. In this age-matched, case-control study performed on ten patients with KS and ten controls, we found that SOX13 is significantly downregulated in peripheral blood mononuclear cells of patients with KS compared to controls. This finding might be consistent with the germ cell loss typical of patients with KS. However, the role of Sox13 in the pathogenesis of germ cell loss and humoral autoimmunity in patients with KS deserves to be further explored.

Assessment of sexual and emotional distress in infertile couple: validation of a new specific psychometric tool

BACKGROUND

The diagnosis of infertility strongly impacts on psychological and sexological couple health. In this regard, some feelings and psychological states were demonstrated in association with reproductive problems. Depression and anxiety are the most common psychopathologies associated with infertility, although also sexuality is strongly involved in infertility conditions.

OBJECTIVES

The aim of this study is to develop a tool to probe and assess the emotional aspects, sexuality, and social relationships of the couple seeking medical care for infertility.

MATERIALS AND METHODS

A self-reported questionnaire that we will refer to as SEIq (Sexuality and Emotions in Infertility questionnaire) was constructed and developed and, consequently, administered to 162 heterosexual couples (324 subjects) seeking help for reproductive problems. Hence, we performed a specific statistical analysis to assess and validate this new psychometric tool.

RESULTS

About 60% of men and women (both partners in 43% of couples) declare that infertility has changed their life (Q10). Moreover, the incidence of sexual disorder declared by the subjects is quite rare in men (10%) but more frequent in women (29%) (p < 0.01).

CONCLUSION AND DISCUSSION

The results of this pilot test show that the diagnosis of infertility impacts on the couple relationship affecting the emotional area, interpersonal relationships, and sexual functions of the couples. Moreover, the SEIq appears a valuable tool to coherently probe and relate sexological, psychological, relational, and emotive aspects in partners and couples facing the infertility diagnosis. The explorative factor analysis of SEIq data allows to understand the women, men, and couples' behavior in our sample, individuating a reduced set of factors, prone to an easier evaluation. On the whole, the psychometric evaluation through SEIq might be suitable for the couples during Assisted Reproductive Technologies treatments.

Clinical Evaluation of a Custom Gene Panel as a Tool for Precision Male Infertility Diagnosis by Next-Generation Sequencing

BACKGROUND

Up to 15% of couples are infertile and male factor infertility accounts for approximately 50% of these cases. Male infertility is a multifactorial pathological condition. The genetic of male infertility is very complex and at least 2000 genes are involved in its etiology. Genetic testing by next-generation sequencing (NGS) technologies can be relevant for its diagnostic value in male infertile patients. Therefore, the aim of this study was to implement the diagnostic offer with the use of an NGS panel for the identification of genetic variants.

METHODS

We developed an NGS gene panel that we used in 22 male infertile patients. The panel consisted of 110 genes exploring the genetic causes of male infertility; namely spermatogenesis failure due to single-gene mutations, central hypogonadism, androgen insensitivity syndrome, congenital hypopituitarism, and primary ciliary dyskinesia.

RESULTS

NGS and a subsequent sequencing of the positive pathogenic or likely pathogenic variants, 5 patients (23%) were found to have a molecular defect. In particular, pathogenic variants were identified in TEX11, CCDC39, CHD7, and NR5A1 genes. Moreover, 14 variants of unknown significance and 7 novel variants were found that require further functional studies and family segregation.

CONCLUSION

This extended NGS-based diagnostic approach may represent a useful tool for the diagnosis of male infertility. The development of a custom-made gene panel by NGS seems capable of reducing the proportion of male idiopathic infertility.

Personalized Medicine for the Infertile Male

Personalized medicine uses a patient's genotype, environment, and lifestyle choices to create a tailored diagnosis and therapy plan, with the goal of minimizing side effects, avoiding lost time with ineffective treatments, and guiding preventative strategies. Although most precision medicine strategies are still within the laboratory phase of development, this article reviews the promising technologies with the greatest potential to improve the diagnosis and treatment options for male infertility, including sperm cell transplantation, genomic editing, and new biomarker assays, based on the latest proteomic and epigenomic studies.

Seminal Plasma Transcriptome and Proteome: Towards a Molecular Approach in the Diagnosis of Idiopathic Male Infertility

As the “-omic” technology has largely developed, its application in the field of medical science seems a highly promising tool to clarify the etiology, at least in part, of the so-called idiopathic male infertility. The seminal plasma (SP) is made-up of secretions coming from the male accessory glands, namely epididymis, seminal vesicles, and prostate. It is not only a medium for sperm transport since it is able to modulate the female reproductive environment and immunity, to allow the acquisition of sperm competence, to influence the sperm RNA content, and even embryo development. The aim of this systematic review was to provide an updated and comprehensive description of the main transcripts and proteins reported by transcriptome and proteome studies performed in the human SP of patients with idiopathic infertility, in the attempt of identifying possible candidate molecular targets. We recurrently found that micro RNA (miR)-34, miR-122, and miR-509 are down-regulated in patients with non-obstructive azoospermia (NOA) and oligozoospermia compared with fertile controls. These molecules may represent interesting targets whose predictive role in testicular sperm extraction (TESE) or assisted reproductive techniques (ART) outcome deserves further investigation. Furthermore, according to the available proteomic studies, ECM1, TEX101, lectingalactoside-binding andsoluble 3 binding protein (LGALS3BP) have been reported as accurate predictors of TESE outcome. Interestingly, ECM1 is differently expressed in patients with different ART outcomes. Further prospective, ample-sized studies are needed to validate these molecular targets that will help in the counseling of patients with NOA or undergoing ART.

Genetic disorders and male infertility

BACKGROUND

At present, one out of six couples is infertile, and in 50% of cases, infertility is attributed to male infertility factors. Genetic abnormalities are found in 10%-20% of patients showing severe spermatogenesis disorders, including non-obstructive azoospermia.

METHODS

Literatures covering the relationship between male infertility and genetic disorders or chromosomal abnormalities were studied and summarized.

MAIN FINDINGS RESULTS

Genetic disorders, including Klinefelter syndrome, balanced reciprocal translocation, Robertsonian translocation, structural abnormalities in Y chromosome, XX male, azoospermic factor (AZF) deletions, and congenital bilateral absence of vas deferens were summarized and discussed from a practical point of view. Among them, understanding on AZF deletions significantly changed owing to advanced elucidation of their pathogenesis. Due to its technical progress, AZF deletion test can reveal their delicate variations and predict the condition of spermatogenesis. Thirty-nine candidate genes possibly responsible for azoospermia have been identified in the last 10 years owing to the advances in genome sequencing technologies.

CONCLUSION

Genetic testing for chromosomes and AZF deletions should be examined in cases of severe oligozoospermia and azoospermia. Genetic counseling should be offered before and after genetic testing.

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.

Development of a novel next-generation sequencing panel for diagnosis of quantitative spermatogenic impairment

PURPOSE

To develop and assess a novel custom next-generation sequencing (NGS) panel for male infertility genetic diagnosis.

METHODS

A total of 241 subjects with diagnosis of idiopathic infertility ranging from azoospermia to normozoospermia were sequenced by a custom NGS panel including AR, FSHB, FSHR, KLHL10, NR5A1, NANOS1, SEPT12, SYCP3, TEX11 genes. Variants with minor allele frequency < 1% were confirmed by Sanger sequencing.

RESULTS

Nineteen missense variants were detected in 23 subjects with abnormal sperm count, whilst no variants were identified in normozoospermic men. Of identified variants, we prioritized variants classified as pathogenic and of uncertain significance (VUS) (63.1%, 12/19). No missense variants were found in males with normal seminal parameters (0/67). Therefore, the prevalence of variants was significantly higher in patients with spermatogenic impairment (16/174 vs 0/67, p = 0.007).

CONCLUSION

This study confirms the utility to apply NGS panel for infertility diagnosis in order to find new genetic variants potentially linked to male infertility with much higher accuracy than standard tests suggested by guidelines. Indeed, based on biological significance, prevalence in the general population and clinical data of patients, it is plausible that identified variants in this study might be linked to quantitative spermatogenic impairment, although further studies are needed.

Molecular Biology of Spermatogenesis: Novel Targets of Apparently Idiopathic Male Infertility

Male infertility affects half of infertile couples and, currently, a relevant percentage of cases of male infertility is considered as idiopathic. Although the male contribution to human fertilization has traditionally been restricted to sperm DNA, current evidence suggest that a relevant number of sperm transcripts and proteins are involved in acrosome reactions, sperm‒oocyte fusion and, once released into the oocyte, embryo growth and development. The aim of this review is to provide updated and comprehensive insight into the molecular biology of spermatogenesis, including evidence on spermatogenetic failure and underlining the role of the sperm-carried molecular factors involved in oocyte fertilization and embryo growth. This represents the first step in the identification of new possible diagnostic and, possibly, therapeutic markers in the field of apparently idiopathic male infertility.