Clinical Review#: State of the art for genetic testing of infertile men

Uncovering the Association Between Complete AZFc Microduplications and Spermatogenic Ability: The First Reported Series

Purpose This article aims to report the first series of men with complete AZFc microduplications and their clinical and reproductive characteristics. Methods We sampled 3000 men who presented for reproductive urology evaluation from 2012-2020, of which 104 men underwent high-resolution Y-chromosome microarray testing, and five men were identified to have complete AZFc microduplications. Medical, surgical, and reproductive histories were obtained. Semen and hormonal parameters as well as response to fertility therapies were recorded. Results Five men were identified as having complete AZFc microduplications. The mean age was 33.75 years, representing 0.2% (5/3000) of men presenting for fertility investigation, 4.8% (5/104) of men undergoing microarray testing, and 21% (5/24) of men with AZFc abnormalities. Two of the men had prior undescended testicles and one had several autoimmune processes. The mean follicle-stimulating hormone (FSH) was 5.5 IU/L, luteinizing hormone (LH) 3.6 IU/L, and testosterone 14.56 nmol/L. One man was azoospermic, one man alternated between severe oligospermia and rare non-motile sperm, one had variable parameters, with one semen analysis demonstrating azoospermia and a second demonstrating a total motile sperm count (TMSC) of 4 ×106, one man was persistently oligospermic with TMSCs ranging 3.96-12.6 ×106, and one man initially had severe oligospermia, with a mean TMSC of 1.5 ×106, which increased to 21.7 ×106 after intervention (varicocele embolization, clomiphene citrate). This last man then fathered a spontaneous pregnancy. Conclusion AZFc complete microduplications are a rare cause of spermatogenic failure but not an uncommon form of AZFc abnormality. Clinically, they represent a heterogeneous group, having a variable reproductive potential. Cases should be managed on an individual basis.

The infertile individual analysis based on whole-exome sequencing in chinese multi-ethnic groups

BACKGROUND

Infertility is a common and rapidly growing health issue around the world. The genetic analysis based on the infertile population is crucial for intervention and treatment.

OBJECTIVE

To find candidate gene locus led to azoospermia in Chinese multi-ethnic groups and provide theoretical guidance for the diagnosis of genetic diseases to progressively aggravated infertility patients and sterile offspring with ART.

METHODS

The study based on whole-exome sequencing (WES) was presented for genetic characteristic analysis of multi-ethnics and identification of variants related to infertility in Xinjiang area of China.

RESULTS

The frequency of pathogenic variants showed significant ethnic differences among four main ethnics in Xinjiang. The population structure analysis confirmed that the Hui was close to the Han population, the Kazak was close to the Uygur population, and there are three ancestry components in the four ethnics. In addition, ten candidate variants potentially regulated azoospermia were detected, and KNTC1 (rs7968222: G > T) was chosen to validate the association. Through the analysis in the valid group, the frequency of rs7968222 (G > T) has a significant difference in the azoospermia population (11.76%, 8/68) and normospermia population (4.63%, 35/756) (P < 0.001). Interestingly, the proportion of people with abnormal follicle-stimulating hormone (FSH) level in the group carrying rs7968222 (G > T) was significantly higher than non-carriers (P < 0.05). Therefore, rs7968222 may regulate spermatogenesis through affecting hormone level.

CONCLUSION

Our study establishes the genetics analysis of Northwest China and finds a candidate gene locus KNTC1 (rs7968222: G > T), which is one of the genetic susceptibility factors for male azoospermia.

Impact of Advanced Paternal Age on Fertility and Risks of Genetic Disorders in Offspring

The average age of fathers at first pregnancy has risen significantly over the last decade owing to various variables, including a longer life expectancy, more access to contraception, later marriage, and other factors. As has been proven in several studies, women over 35 years of age have an increased risk of infertility, pregnancy problems, spontaneous abortion, congenital malformations, and postnatal issues. There are varying opinions on whether a father's age affects the quality of his sperm or his ability to father a child. First, there is no single accepted definition of old age in a father. Second, much research has reported contradictory findings in the literature, particularly concerning the most frequently examined criteria. Increasing evidence suggests that the father's age contributes to his offspring's higher vulnerability to inheritable diseases. Our comprehensive literature evaluation shows a direct correlation between paternal age and decreased sperm quality and testicular function. Genetic abnormalities, such as DNA mutations and chromosomal aneuploidies, and epigenetic modifications, such as the silencing of essential genes, have all been linked to the father's advancing years. Paternal age has been shown to affect reproductive and fertility outcomes, such as the success rate of in vitro fertilisation (IVF), intracytoplasmic sperm injection (ICSI), and premature birth rate. Several diseases, including autism, schizophrenia, bipolar disorders, and paediatric leukaemia, have been linked to the father's advanced years. Therefore, informing infertile couples of the alarming correlations between older fathers and a rise in their offspring's diseases is crucial, so that they can be effectively guided through their reproductive years.

Effects of Chromosomal Translocations on Sperm Count in Azoospermic and Oligospermic Cases

Purpose A number of mechanisms have been proposed for the effect of chromosomal translocations on spermatogenesis and sperm maturation. However, there are still numerous ambiguous issues regarding these two processes. The aim of this study is to evaluate the effect of chromosome break areas on sperm count in the light of the literature. Material and Methods The study was conducted on the data of 16 male patients with reciprocal or Robertsonian translocation among 152 patients who were admitted to Adana Numune Training and Research Hospital and Kanuni Sultan Süleyman Training and Research Hospital Genetic Diagnosis Centers between 2013 and 2016 due to azoospermia and oligospermia. Results 11 of these patients had reciprocal and five patients had Robertsonian translocations. All the patients with Robertsonian translocations were detected with azoospermia. Of the patients with reciprocal translocation, five of them were azoospermic and six of them were severe oligospermic. Conclusion A total of 21 chromosomal breakpoints were identified in the 11 patients with reciprocal translocations. These chromosomal breakpoints may contribute to the clarification of ambiguous issues related to spermatogenesis and sperm maturation. The results also showed the importance of genetic counselling in patients with translocations.

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.

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.

[Systematic karyotyping before ICSI: A necessary procedure? Analysis of case studies in the Nancy University Hospital Fertility Centre]

INTRODUCTION

A constitutional karyotype is often assayed for the couple before ICSI management. The objective of this study was to assess the prevalence of chromosomal abnormality in an infertile population, the impact on the care of couples and its cost.

METHODS

A single-center retrospective study was carried out at the Fertility Center of the University Hospital of Nancy, including all infertile couples who underwent a karyotype analysis from June 2009 to December 2016.

RESULTS

1252 couples were included. 7.9% had at least one abnormal karyotype. A change in care affected 22% of these couples, i.e. 1.7% of the total population. 9% of couples with karyotype abnormality underwent PGD. In the male population, the percentage of abnormal spermograms is significantly higher in the group with karyotype abnormality compared to the control group (85.7% vs. 46.5%, P<0.001).

DISCUSSION

The constitutional karyotype, due to its high economic and human cost, and limited interest, is a screening method for chromosomal abnormalities that has no place systematically before performing IVF. The future lies in the restriction of the indications for prescribing the karyotype as well as in the realization of PGS in targeted situations.

Semen analysis: a workflow for an appropriate assessment of the male fertility status

Infertility is a worldwide problem that affects 9-15% of couples of reproductive age. In about half of the cases, it recognizes, alone or in combination, a male cause. In addition to a reproductive problem, male infertility can result from a systemic disease. Consequently, semen analysis, a fundamental test in the diagnosis of male infertility, represents a useful indicator not only of a man's reproductive capacity but also of his health and lifestyle. Given the key role of semen analysis, only accredited laboratories should perform it and experienced clinicians should be called into play in its interpretation. In this article, we have extensively examined how the macroscopic and microscopic parameters of semen analysis, alone or associated with each other, allow clinicians to orient towards specific diagnoses that can be confirmed by further ad hoc tests. On this basis, we also proposed a diagnostic flowchart focused on the results of the semen analysis.

Genetics of Male Infertility - Present and Future: A Narrative Review

Infertility affects 8%–12% of couples worldwide with a male factor contributing to nearly 50% of couples either as a primary or contributing cause. Several genetic factors that include single-gene and multiple-gene defects associated with male infertility were reported in the past two decades. However, the etiology remains ambiguous in a majority of infertile men (~40%). The objective of this narrative review is to provide an update on the genetic factors associated with idiopathic male infertility and male reproductive system abnormalities identified in the last two decades. We performed a thorough literature search in online databases from January 2000 to July 2021. We observed a total of 13 genes associated with nonobstructive azoospermia due to maturation/meiotic arrest. Several studies that reported novel genes associated with multiple morphological abnormalities of the sperm flagella are also discussed in this review. ADGRG2, PANK2, SCNN1B, and CA12 genes are observed in non-CFTR-related vas aplasia. The genomic analysis should be quickly implemented in clinical practice as the detection of gene abnormalities in different male infertility phenotypes will facilitate genetic counseling.

Maternal and Paternal Representations in Assisted Reproductive Technology and Spontaneous Conceiving Parents: A Longitudinal Study

Aim of this study was to investigate whether parental mental representations during pregnancy and after delivery differed between parents who conceived after Assisted Reproductive Treatments (ART) and spontaneous conceiving (SC) parents. Effects of specific ART variables (previous ART attempts, treatment type and cause of infertility) were also taken into account. Seventeen ART couples and 25 SC couples were recruited at Santa Maria Nuova Hospital (Reggio Emilia, Italy). At both 32 weeks of gestation (T1) and 3 months postpartum (T2) participants completed the Semantic Differential of the IRMAG, a self-report tool which measures specific domains of mental representations pertaining either individual (Child, Self-as-woman/man, and Partner) or parental (Self-as-parent, Own parent) characteristics. Results showed that ART parents had significantly more positive representations of the child compared to SC parents, while the scores at Partner dimension improved from T1 to T2 for SC parents only. With regards to ART history, scores at the Self-as-woman/man dimension were significantly less positive for ICSI than IVF parents and improved substantially from T1 to T2 only in case of mothers with previous ART attempts and of fathers at the first ART cycle. The representation of own parents increased from T1 to T2 in case of infertility diagnosis due to male factors, while a decrease emerged when infertility was due to female factors. Findings suggest the need to investigate parental mental representations after ART, in order to improve the understanding on the transition to parenthood of infertile couples and to target more specific intervention for parenting support.

Male infertility due to testicular disorders

CONTEXT

Male infertility is defined as the inability to conceive following 1 year of regular unprotected intercourse. It is the causative factor in 50% of couples and a leading indication for assisted reproductive techniques (ART). Testicular failure is the most common cause of male infertility, yet the least studied to date.

EVIDENCE ACQUISITION

The review is an evidence-based summary of male infertility due to testicular failure with a focus on etiology, clinical assessment, and current management approaches. PubMed-searched articles and relevant clinical guidelines were reviewed in detail.

EVIDENCE SYNTHESIS/RESULTS

Spermatogenesis is under multiple levels of regulation and novel molecular diagnostic tests of sperm function (reactive oxidative species and DNA fragmentation) have since been developed, and albeit currently remain as research tools. Several genetic, environmental, and lifestyle factors provoking testicular failure have been elucidated during the last decade; nevertheless, 40% of cases are idiopathic, with novel monogenic genes linked in the etiopathogenesis. Microsurgical testicular sperm extraction (micro-TESE) and hormonal stimulation with gonadotropins, selective estrogen receptor modulators, and aromatase inhibitors are recently developed therapeutic approaches for men with the most severe form of testicular failure, nonobstructive azoospermia. However, high-quality clinical trials data is currently lacking.

CONCLUSIONS

Male infertility due to testicular failure has traditionally been viewed as unmodifiable. In the absence of effective pharmacological therapies, delivery of lifestyle advice is a potentially important treatment option. Future research efforts are needed to determine unidentified factors causative in "idiopathic" male infertility and long-term follow-up studies of babies conceived through ART.

Nonsurgical Management of Oligozoospermia

Male infertility secondary to oligozoospermia is surprisingly common. Although a majority of cases are idiopathic, oligozoospermia can be caused by endocrine dysfunction, anatomic abnormalities, medications, or environmental exposures. The work-up includes excluding reversible factors such as hormonal deficiency, medication effects, and retrograde ejaculation and identifying any underlying genetic syndrome and treating reversible medical causes. If no reversible cause is found, appropriate referrals to urology and assisted reproductive technology should be initiated. Lastly, clinicians should be aware of and respond to the psychological and general health ramifications of a diagnosis of oligozoospermia as part of the comprehensive care of men and couples struggling with a diagnosis of infertility.

Indication for Y Chromosome Microdeletion Analysis in Infertile Men: Is a New Sperm Concentration Threshold Needed?

OBJECTIVE

To describe the prevalence of Y-chromosome deletions in patients with a sperm concentration of less than 5 million/mL. To also determine a new sperm threshold for Y-chromosome analysis in men with infertility.

METHODS

A total of 3023 patients who had a semen concentration of less than 5 million/mL included in this retrospective study. All of these patients had a genetic evaluation, hormonal evaluation, and 2 abnormal semen analyses.

RESULTS

Y-chromosome deletions were present in 116 (3.8 %) patients with sperm concentration <5 million/mL. The frequency of a Y-chromosome deletions was 6.8%, 1.0%, 0.15% in azoospermic men, in men with sperm concentrations of 0-1 million /mL, in men with sperm concentrations of 1-5 million/mL. Patients were divided into 2 groups regarding the determined new sperm threshold. The sensitivity and specificity of the Y-chromosome deletions test were 92.2.7% and 49.3 %, 99.1%, and 22.1% in patients with azoospermia and sperm concentrations <1 million/mL, respectively. If the sperm concentration thresholds of azoospermia or <1 million/mL, are applied, the number of tests decreased to 50.5% (1442 tests) and 23.1% (643 tests), respectively. Approximately $108,150 and $48,225 would be saved if the sperm thresholds were azoospermia and <1 million/mL, respectively CONCLUSION: The current threshold of sperm concentration for Y-chromosome deletions is controversial. The new proposed sperm threshold for genetic testing of 1 million/mL would increase sensitivity and more cost-effective compared to the current threshold.

First custom next-generation sequencing infertility panel in Latin America: design and first results

Objective

To present the development of the first custom gene panel for the diagnosis of male and female infertility in Latin America.

Methods

We developed a next-generation sequencing (NGS) panel that assesses genes associated with infertility. The panel targeted exons and their flanking regions. Selected introns in the CFTR gene were also included. The FMR1 gene and Y chromosome microdeletions were analyzed with other recommended methodologies. An in-house developed bioinformatic pipeline was applied for the interpretation of the results. Clear infertility phenotypes, idiopathic infertility, and samples with known pathogenic variants were evaluated.

Results

A total of 75 genes were selected based on female (primary ovarian insufficiency, risk of ovarian hyperstimulation syndrome, recurrent pregnancy loss, oocyte maturation defects, and embryo development arrest) and male conditions (azoospermia, severe oligospermia, asthenozoospermia, and teratozoospermia). The panel designed was used to assess 25 DNA samples. Two of the variants found were classified as pathogenic and enable the diagnosis of a woman with secondary amenorrhea and a man with oligoasthenoteratozoospermia. Targeted NGS assay metrics resulted in a mean of 180X coverage, with more than 98% of the bases covered ≥20X.

Conclusion

Our custom gene sequencing panel designed for the diagnosis of male and female infertility caused by genetic defects revealed the underlying genetic cause of some cases of infertility. The panel will allow us to develop more precise approaches in assisted reproduction.

A framework for high-resolution phenotyping of candidate male infertility mutants: from human to mouse

Male infertility is a heterogeneous condition of largely unknown etiology that affects at least 7% of men worldwide. Classical genetic approaches and emerging next-generation sequencing studies support genetic variants as a frequent cause of male infertility. Meanwhile, the barriers to transmission of this disease mean that most individual genetic cases will be rare, but because of the large percentage of the genome required for spermatogenesis, the number of distinct causal mutations is potentially large. Identifying bona fide causes of male infertility thus requires advanced filtering techniques to select for high-probability candidates, including the ability to test causality in animal models. The mouse remains the gold standard for defining the genotype-phenotype connection in male fertility. Here, we present a best practice guide consisting of (a) major points to consider when interpreting next-generation sequencing data performed on infertile men, and, (b) a systematic strategy to categorize infertility types and how they relate to human male infertility. Phenotyping infertility in mice can involve investigating the function of multiple cell types across the testis and epididymis, as well as sperm function. These findings will feed into the diagnosis and treatment of male infertility as well as male health broadly.

MicroRNAs association with azoospermia, oligospermia, asthenozoospermia, and teratozoospermia: a systematic review

Infertility is a major health problem across the world. One of the main reasons for male infertility are defects in sperm. Semen analysis is the most common test utilized to evaluate male fertility and since it suffers from multiple drawbacks, reproduction scientists have tried to find new molecular markers for detecting sperm defects. MicroRNAs (miRNAs) are small molecules in cells which take part in regulating gene expression. Various studies have confirmed miRNAs to have a role in defining multiple sperm characteristics, including sperm count, motility, and morphology. In this paper, we have systematically reviewed the role of miRNAs in infertile men with sperm defects including azoospermia, oligospermia, asthenozoospermia, and teratozoospermia. Also, we have assembled various bioinformatics tools to come up with a pipeline for predicting novel miRNAs which could possibly participate in sperm count, motility, and morphology. Also, related KEGG and GO terms for predicted miRNAs have been included in order to highlight their role in sperm function. Our study emphasizes the potential role of miRNAs in male infertility and provides a general overview for future studies aiming to find robust molecular markers for this condition.

Influence of variation in global sperm DNA methylation level on the expression level of protamine genes and human semen parameters

An infertility problem is a complex issue that affects 15% approximately of couples worldwide. The current study was designed to evaluate if there is a variation in the status of global DNA methylation among the study groups and to assess their impact on the protamine expression level and human semen parameters. Totalling 200 semen samples were collected from men (50 proved fertile, 60 normospermia and 90 oligospermia) with an average age of 34.9 ± 4.3 years. The DNA and RNA were isolated from purified spermatozoa; then, ELISA and qPCR were applied to estimate the status of global sperm DNA methylation and protamine expression level respectively. Besides that, the sperm chromatin decondensation and sperm DNA fragmentation were assessed. A significant variation was found in the global sperm DNA methylation and the protamine 1 and protamine 2 expression level among the study groups (p ≤ .001). Down-regulation has been found in the protamine 1 and protamine 2 expression levels in the oligospermia group compared to the proved fertile group with fold change (0.001 and 0.0002 respectively). In conclusion, this study proposes that the alteration in global DNA methylation may influence the protamine expression level and may be lead to abnormalities in human semen parameters.

Genome-Wide Adductomics Analysis Reveals Heterogeneity in the Induction and Loss of Cyclobutane Thymine Dimers across Both the Nuclear and Mitochondrial Genomes

The distribution of DNA damage and repair is considered to occur heterogeneously across the genome. However, commonly available techniques, such as the alkaline comet assay or HPLC-MS/MS, measure global genome levels of DNA damage, and do not reflect potentially significant events occurring at the gene/sequence-specific level, in the nuclear or mitochondrial genomes. We developed a method, which comprises a combination of Damaged DNA Immunoprecipitation and next generation sequencing (DDIP-seq), to assess the induction and repair of DNA damage induced by 0.1 J/cm² solar-simulated radiation at the sequence-specific level, across both the entire nuclear and mitochondrial genomes. DDIP-seq generated a genome-wide, high-resolution map of cyclobutane thymine dimer (T<>T) location and intensity. In addition to being a straightforward approach, our results demonstrated a clear differential distribution of T<>T induction and loss, across both the nuclear and mitochondrial genomes. For nuclear DNA, this differential distribution existed at both the sequence and chromosome level. Levels of T<>T were much higher in the mitochondrial DNA, compared to nuclear DNA, and decreased with time, confirmed by qPCR, despite no reported mechanisms for their repair in this organelle. These data indicate the existence of regions of sensitivity and resistance to damage formation, together with regions that are fully repaired, and those for which > 90% of damage remains, after 24 h. This approach offers a simple, yet more detailed approach to studying cellular DNA damage and repair, which will aid our understanding of the link between DNA damage and disease.

Obstetric and perinatal outcomes of intracytoplasmic sperm injection for infertile men with Y chromosome microdeletions

BACKGROUND

To evaluate the safety of intracytoplasmic sperm injection (ICSI) for men with Y chromosome azoospermia factor (AZF) microdeletions.

METHODS

Twenty-five men with Y chromosome microdeletions and their partners underwent ICSI treatment. These subjects were matched against 50 ICSI cycles in which the patients had normal Y chromosomes.

RESULTS

Among the 25 couples, 17 achieved a clinical pregnancy of which 14 continued to a live birth. Sixteen men had deletions of AZFc markers (sY152, sY254, and sY255), 1 had a deletion of sY152, 3 had a deletion of sY254, sY255, 1 had a deletion of sY152, sY239, Sy242, sY254, and sY255, and 3 had deletions of sY152, sY254, sY255, and sY157. AZFb microdeletions (sY127, sY134, and sY143) were found in 1 patient. AZF microdeletions had no adverse effects on the clinical pregnancy, implantation or delivery rates, birth weight, gestational age, or sex ratio when compared with the control group. Overall, the multiple gestation and preterm delivery rates of the AZF microdeletion group were similar to those in the control group.

CONCLUSION

Men with AZF microdeletions can achieve the delivery of healthy children using ICSI. In this series, it produced good implantation rate and obstetric and perinatal outcomes.

The Challenges of Chromosome Y Analysis and the Implications for Chronic Kidney Disease

The role of chromosome Y in chronic kidney disease (CKD) remains unknown, as chromosome Y is typically excluded from genetic analysis in CKD. The complex, sex-specific presentation of CKD could be influenced by chromosome Y genetic variation, but there is limited published research available to confirm or reject this hypothesis. Although traditionally thought to be associated with male-specific disease, evidence linking chromosome Y genetic variation to common complex disorders highlights a potential gap in CKD research. Chromosome Y variation has been associated with cardiovascular disease, a condition closely linked to CKD and one with a very similar sexual dimorphism. Relatively few sources of genetic variation in chromosome Y have been examined in CKD. The association between chromosome Y aneuploidy and CKD has never been explored comprehensively, while analyses of microdeletions, copy number variation, and single-nucleotide polymorphisms in CKD have been largely limited to the autosomes or chromosome X. In many studies, it is unclear whether the analyses excluded chromosome Y or simply did not report negative results. Lack of imputation, poor cross-study comparability, and requirement for separate or additional analyses in comparison with autosomal chromosomes means that chromosome Y is under-investigated in the context of CKD. Limitations in genotyping arrays could be overcome through use of whole-chromosome sequencing of chromosome Y that may allow analysis of many different types of genetic variation across the chromosome to determine if chromosome Y genetic variation is associated with CKD.

Duplications in 19p13.3 are associated with male infertility

PURPOSE

To identify genomic imbalances and candidate loci in idiopathic male infertility.

METHODS

Affymetrix CytoScan 750K Array was used to analyze genomic imbalances and candidate loci in 34 idiopathic infertile cases of different phenotypes (hypo-spermatogenesis, n = 8; maturation arrest, n = 7; and Sertoli cell-only syndrome, n = 13, severe oligozoospermia, n = 6, and 10 normozoospermic fertile men). Ten ethnically matched controls were screened for comparison.

RESULTS

The cytogenetic array analysis detected a genomic gain at the 19p13.3 region in 9 (26.47%) cases, with the highest frequency in patients with Sertoli cell-only syndrome (SCOS) (38%). Its complete absence in the control group suggests its likely pathogenic nature. In addition to Y-classical, micro, and partial deletions, the duplication in 19p13.3 could serve as a unique biomarker for evaluation of infertility risk. The common region across the individuals harboring the duplication identified STK11, ATP5D, MIDN, CIRBP, and EFNA2 genes which make them strong candidates for further investigations. The largest duplicated region identified in this study displayed a major network of 7 genes, viz., CIRBP, FSTL3, GPX4, GAMT, KISS1R, STK11, and PCSK4, associated with reproductive system development and function. The role of chance was ruled out by screening of ethnically matched controls.

CONCLUSION

The result clearly indicates the significance of 19p13.3 duplication in infertile men with severe testicular phenotypes. The present study underlines the utility and significance of whole genomic analysis in the cases of male infertility which goes undiagnosed due to limitations in the conventional cytogenetic techniques and for identifying genes that are essential for spermatogenesis.

Decrease in semen quality and Leydig cell function in infertile men: a longitudinal study

STUDY QUESTION

Are infertile men with reduced semen quality at risk of a further decrease in testicular function?

SUMMARY ANSWER

Infertile men with severely reduced semen quality risk further deterioration of semen quality 15 years after treatment for infertility, and a lower baseline sperm concentration was associated with a more pronounced increase in LH and decrease in testosterone/LH ratio at follow-up.

WHAT IS KNOWN ALREADY

Male factors account for up to 50% of human infertility. The most common finding is spermatogenic failure (SgF) yet the life course of semen quality and testosterone production in such men has not been described.

STUDY DESIGN, SIZE, DURATION

A follow-up study of men with SgF was performed 15 years after the initial infertility assessment between January 1995 and December 2000.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Hospital records were used to identify potential participants in the study. A total of 137 men with primary male infertility due to SgF and 70 controls with good semen quality from couples with female factor infertility who attended a tertiary referral centre were included: the participation rate was 31% and 26%, respectively. The men provided semen samples and underwent a physical examination. Blood samples were taken to measure levels of reproductive hormones (FSH, LH, testosterone, sex hormone-binding globulin, estradiol and inhibin B). Current results were compared with results from the initial assessments.

MAIN RESULTS AND THE ROLE OF CHANCE

At the time of follow up the SgF men had significantly lower Leydig cell capacity than the control group as well as much lower semen quality. For the SgF men, between baseline sampling and follow up, the median sperm concentration decreased from 1.9 to 0.6 mill/ml and total sperm count from 7.7 to 2.0 million (P = 0.019 and 0.012, respectively), and 10% developed azoospermia. Calculated free testosterone (cFT), but not total testosterone (tT) decreased in the SgF group by ~0.6% (95% CI 0.1-1.2%) per year. In the SgF group, LH increased by 1.6% (CI 0.9-2.3%) annually, and consequently tT/LH and cFT/LH ratios had decreased by 1.3% (CI 0.5-2.1) and 2.1% (CI 1.2-3.0%), respectively. The increase in LH and the decreases in tT/LH and cFT/LH ratios were more pronounced in men with lower baseline sperm concentrations.

LIMITATIONS, REASONS FOR CAUTION

We consider the case group as representative of infertile men not in need of testosterone treatment at baseline investigation, but do not have information on those that chose not to participate in the follow-up study. There were alterations in some hormone analysis methods during the follow-up period that may introduce uncertainty in interpretation of long-term changes in hormone levels despite rigorous quality control. The validity of the control group suffers from a lack of hormone values at baseline. Also, at follow-up, for practical reasons only one semen sample could be obtained, which makes the effect estimate more uncertain and there is a risk of non-differential misclassification.

WIDER IMPLICATIONS OF THE FINDINGS

Without being able to predict individual outcomes, it is prudent to consider sperm cryopreservation or advise not to postpone fertility treatment when men present with infertility due to impaired semen quality. Whether partly compensated Leydig cell insufficiency in men with SgF will eventually develop into overt testosterone deficiency cannot be determined from our study.

STUDY FUNDING/COMPETING INTEREST(s)

Aase and Einar Danielsen (Grant no. 10-001053), Nordic Research Committee (Grant no. 5109), The Kirsten and Freddie Johansen Fund, and Rigshospitalet's Research Fund (grant no. R24-A812). There are no competing interests.

Sperm retrieval rate and reproductive outcome of infertile men with azoospermia factor c deletion

To evaluate the success rate in sperm retrieval (SR) through microdissection testicular sperm extraction (micro-TESE) in infertile azoospermia factor c (AZFc)-deleted men and determining their reproductive outcomes following ICSI, medical records of couples with AZFc-deleted male partners were reviewed on patient's age, serum hormone levels, karyotype, testicular pathology and pregnancy outcomes. A comparison on age and serum hormone level was conducted between groups with positive and negative sperm retrieval in both azoospermic and oligozoospermic AZFc-deleted men. Of 225 who had AZFc deletion, 195 cases followed clinical treatments. From 195 cases, 116 were azoospermic, 79 were oligozoospermic. Pathology profile was available in 103 of 195 subjects which the predominant trait was SCOS and was seen in 66.9% of cases (69 of 103). Success rate of sperm retrieval in azoospermic patients who underwent micro-TESE was 36.3% (28/77). Forty-three oligozoospermic and 17 azoospermic patients started ART cycle. Pregnancy rate in oligozoospermic group was 35.4% (17 cases), whilst there was no clinical pregnancy in azoospermic group. In conclusion, the pregnancy and delivery in oligozoospermic patients with AZFc deletion are comparable with other studies, but despite of sperm retrieval in azoospermic patients with AZFc deletion, the chance of pregnancy or delivery in these patients was very low.

Novel Epigenomic Biomarkers of Male Infertility Identified by Methylation Patterns of CpG Sites Within Imprinting Control Regions of H19 and SNRPN Genes

Male infertility is an important global health burden that can benefit from novel biomarkers and diagnostics innovation. Aberrant methylation of the imprinted genes H19 and SNRPN (small nuclear ribonucleoprotein polypeptide N) in sperm DNA has been implicated in abnormal sperm parameters and male infertility. However, whether certain methylation patterns of one or multiple CpG sites within an imprinted gene are pathological for multiple sperm defects remains poorly understood. To examine the diagnostic potential of certain methylation patterns of CpG sites for multiphenotype defects in human sperm, the sperm DNA methylation patterns of individual CpG sites within imprinting control regions (ICRs) of imprinted genes H19 and SNRPN were measured by bisulfite pyrosequencing in a Han Chinese population sample: 39 oligoasthenozoospermia (OA) patients, 36 asthenoteratozoospermia (AT) patients, and 50 normozoospermia (N) controls. A partial least squares discriminant analysis model was built with the CpG sites as independent variables. Among the 16 CpG sites screened, the methylation patterns of eight CpG sites within H19-ICR (CpG sites 1, 6-9, 12 and 15-16), and eight CpG sites within SNRPN-ICR (CpG sites 2, 5-6, 8-10, 13, and 16) correctly classified 74.4% and 72.0% of the samples in terms of male fertile status, respectively. Furthermore, by combination of these 16 selected CpG sites within ICRs of H19 and SNRPN, 88.0% of the samples could be successfully classified. Our study demonstrates that methylation profiles of CpG sites within ICRs of imprinted genes H19 and SNRPN may potentially serve as epigenomic biomarkers for assessment of infertility in men with multiple sperm defects. Further studies in independent population samples are called for diagnostic significance of methylation patterns of CpG sites within imprinted genes.

Disorders of spermatogenesis: Perspectives for novel genetic diagnostics after 20 years of unchanged routine

Infertility is a common condition estimated to affect 10-15% of couples. The clinical causes are attributed in equal parts to the male and female partners. Diagnosing male infertility mostly relies on semen (and hormone) analysis, which results in classification into the two major phenotypes of oligo- and azoospermia. The clinical routine analyses have not changed over the last 20 years and comprise screening for chromosomal aberrations and Y‑chromosomal azoospermia factor deletions. These tests establish a causal genetic diagnosis in about 4% of unselected men in infertile couples and 20% of azoospermic men. Gene sequencing is currently only performed in very rare cases of hypogonadotropic hypogonadism and the CFTR gene is routinely analysed in men with obstructive azoospermia. Still, a large number of genes have been proposed to be associated with male infertility by, for example, knock-out mouse models. In particular, those that are exclusively expressed in the testes are potential candidates for further analyses. However, the genome-wide analyses (a few array-CGH, six GWAS, and some small exome sequencing studies) performed so far have not lead to improved clinical diagnostic testing. In 2017, we started to routinely analyse the three validated male infertility genes: NR5A1, DMRT1, and TEX11. Preliminary analyses demonstrated highly likely pathogenic mutations in these genes as a cause of azoospermia in 4 men, equalling 5% of the 80 patients analysed so far, and increasing the diagnostic yield in this group to 25%. Over the past few years, we have observed a steep increase in publications on novel candidate genes for male infertility, especially in men with azoospermia. In addition, concerted efforts to achieve progress in elucidating genetic causes of male infertility and to introduce novel testing strategies into clinical routine have been made recently. Thus, we are confident that major breakthroughs concerning the genetics of male infertility will be achieved in the near future and will translate into clinical routine to improve patient/couple care.

A report of nine cases and review of the literature of infertile men carrying balanced translocations involving chromosome 5

Background

Balanced translocations may cause the loss of genetic material at the breakpoints and may result in failure of spermatogenesis. However, carriers of reciprocal translocation may naturally conceive. Genetic counseling of male carriers of translocations remains challenging. This study explores the clinical features of carriers of chromosome 5 translocations, enabling informed genetic counseling of these patients.

Results

Of 82 translocation carriers, 9 (11%) were carriers of a chromosome 5 translocation. One case had azoospermia, while three cases had experienced recurrent spontaneous abortions, two cases had each experienced stillbirth, and three cases produced a phenotypically normal child confirmed by amniocentesis. A literature review identified 106 patients who carried chromosome 5 translocations. The most common chromosome 5 translocation was t(4,5), observed in 13 patients. Breakpoint at 5p15 was observed in 11 patients. All breakpoints at chromosome 5 were associated with gestational infertility.

Conclusion

In genetic counseling, physicians should consider chromosome 5 and its breakpoints. Carriers of chromosome 5 translocations may continue with natural conception or use assisted reproductive technologies, such as preimplantation genetic diagnosis.

Ten cases with 46,XX testicular disorder of sex development: single center experience

Objective

To present clinical, chromosomal and hormonal features of ten cases with SRY-positive 46,XX testicular disorder of sex development who were admitted to our infertility clinic.

Cases and Methods

Records of the cases who were admitted to our infertility clinic between 2004 and 2015 were investigated. Ten 46,XX testicular disorder of sex development cases were detected. Clinical, hormonal and chromosomal assessments were analized.

Results

Mean age at diagnosis was 30.4, mean body height was 166.9cm. Hormonal data indicated that the patients had a higher FSH, LH levels, lower TT level and normal E2, PRL levels. Karyotype analysis of all patients confirmed 46,XX karyotype, and FISH analysis showed that SRY gene was positive and translocated to Xp. The AZFa, AZFb and AZFc regions were absent in 8 cases. In one case AZFb and AZFc incomplete deletion and normal AZFa region was present. In the other one all AZF regions were present.

Conclusion

Gonadal development disorders such as SRY-positive 46,XX testicular disorder of sex development can be diagnosed in infertility clinics during infertility work-up. Although these cases had no chance of bearing a child, they should be protected from negative effects of testosterone deficiency by replacement therapies.

Aberrations in sperm DNA methylation patterns of males suffering from reduced fecundity

The purpose of this study was to evaluate the aberrations in sperm DNA methylation patterns of males suffering from reduced fecundity. A total of 108 males (65 males suffering from reduced fecundity as cases and 43 proven fertile males as a control) were included in the study. Thirty samples were subjected to 450K arrays as a screening phase, and then, three CpG sites located in the following genes: TYRO3, CGβ and FAM189A1 were selected to validate on 78 samples using deep bisulphite sequencing. A significant difference in the methylation level was found between cases and controls at all CpGs in TYRO3 gene-related amplicon (CpG1, p ≤ .003, CpG2, p ≤ .0001, CpG3, p ≤ .003 and CpG4, p ≤ .030) and CpG1 in CGβ gene-related amplicon (p ≤ .0001). Besides, a significant difference was found at two CpGs (CpG1, p ≤ .004 and CpG2, p ≤ .002) tested in the FAM189A1 gene-related amplicon. A significant correlation was found between the methylation level at CpG1 in the FAM189A1 gene and the different types of sperm motility. In conclusion, an alteration in the methylation levels of sperm DNA from males with reduced fecundity was showed. In addition, a relationship between variations in the methylation level of these CpGs and sperm motility has been observed.

Relationship of genetic causes and inhibin B in non obstructive azoospermia spermatogenic failure

Background

Chromosomal disorders in non obstructive azoospermia (NOA) may have an important influence on spermatogenesis, which may be reflected by the serum inhibin B levels. Till now, few studies have concerned the relationship of genetic causes and inhibin B in NOA.

Methods

In this retrospective study, 322 men with NOA in Center for Reproductive Medicine, Nanfang Hospital, Southern Medical University were collected. The level of follicle stimulating hormone (FSH), inhibin B, Y chromosome microdeletion test (YCMD) and karyotype were measured.

Results

Abnormal karyotypes were present in 38.5% of NOA, and YCMD were present in 18.0%, there was a high correlation between karyotypes and YCMD (χ² = 11.892, P < 0.001). The level of inhibin B in chromosomal abnormality from lowest to highest was 46,XX (or 45,X), 47, XXY, mosaics, polymorphisms, inversion and translocation. And the level of inhibin B within Non-AZF a&b region deletion was higher than AZF a&b microdeletion.

Conclusion

According to the level of inhibin B, spermatogenesis in chromosomal abnormality from lowest to highest was 46,XX (or 45,X), 47, XXY, mosaics, polymorphisms, inversion and translocation. And spermatogenesis within Non-AZF a&b region deletion was better than AZF a&b microdeletion.

Incidence of Y-chromosome microdeletions in children whose fathers underwent vasectomy reversal or in vitro fertilization with epididymal sperm aspiration: a case-control study

Objective

To evaluate the incidence of Y-chromosome microdeletions in individuals born from vasectomized fathers who underwent vasectomy reversal or in vitro fertilization with sperm retrieval by epididymal aspiration (percutaneous epididymal sperm aspiration).

Methods

A case-control study comprising male children of couples in which the man had been previously vasectomized and chose vasectomy reversal (n=31) or in vitro fertilization with sperm retrieval by percutaneous epididymal sperm aspiration (n=30) to conceive new children, and a Control Group of male children of fertile men who had programmed vasectomies (n=60). Y-chromosome microdeletions research was performed by polymerase chain reaction on fathers and children, evaluating 20 regions of the chromosome.

Results

The results showed no Y-chromosome microdeletions in any of the studied subjects. The incidence of Y-chromosome microdeletions in individuals born from vasectomized fathers who underwent vasectomy reversal or in vitro fertilization with spermatozoa recovered by percutaneous epididymal sperm aspiration did not differ between the groups, and there was no difference between control subjects born from natural pregnancies or population incidence in fertile men.

Conclusion

We found no association considering microdeletions in the azoospermia factor region of the Y chromosome and assisted reproduction. We also found no correlation between these Y-chromosome microdeletions and vasectomies, which suggests that the assisted reproduction techniques do not increase the incidence of Y-chromosome microdeletions.

A nonsense mutation in Ccdc62 gene is responsible for spermiogenesis defects and male infertility in repro29/repro29 mice

Phenotype-driven mutagenesis is an unbiased method to identify novel genes involved in spermatogenesis and other reproductive processes. Male repro29/repro29 mice generated by the Reproductive Genomics Program at the Jackson Laboratory were infertile with deformed sperm and poor motility. Using selected exonic capture and massively parallel sequencing technologies, we identified a nonsense mutation in the exon 6 of coiled-coil domain-containing 62 gene (Ccdc62), which results in a formation of a premature stop codon and a truncated protein. Among the tissues examined, CCDC62 was found to be expressed at the highest level in mouse testis by reverse transcriptase-PCR (RT-PCR) and Western blot analysis. With immunofluorescent staining, we demonstrated that CCDC62 was expressed in the cytoplasm and the developing acrosome in the spematids of mouse testis, and was specifically localized at the acrosome in mature sperm. The complementation analysis by mating repro29/+ mice with Ccdc62 -/- mice (generated by CRISPR-Cas9 strategy) further provided genetic proof that the infertility of repro29/repro29 mice was caused by Ccdc62 mutation. Finally, it was found that intracellular colocalization and interaction of CCDC62 and Golgi-associated PDZ and coiled-coil motif-containing protein may be important for acrosome formation. Taken together, this study identified a nonsense mutation in Ccdc62, which directly results in male infertility in repro29/repro29 mice.

Outcomes of intracytoplasmic sperm injection in oligozoospermic men with Y chromosome AZFb or AZFc microdeletions

We investigated whether the presence of Y chromosome azoospermia factor (AZF) microdeletions impacts upon the outcomes of intracytoplasmic sperm injection (ICSI) using fresh ejaculated spermatozoa. Sixteen oligozoospermia patients with Y chromosome AZFb or AZFc microdeletions and undergoing ICSI cycles between March 2013 and November 2014 were studied. Twenty-six infertile men with normal Y chromosomes and also undergoing IVF/ICSI in the same time period were used as controls. A retrospective case-control study approach was used. Among the 16 cases, 12 (75%, 12/16) had deletions of AZFc markers (sY152, sY254 and sY255), one (6.25%, 1/16) had a deletion of sY152, and two (12.5%, 2/16) had deletions of sY152, sY254, sY255 and sY157. AZFb microdeletions were found in one patient (6.25%, 1/16). There were no significant differences between groups for cleaved embryo rate, high-grade embryo rate, blastocyst formation rate, embryo implantation rate, clinical pregnancy rate and delivery rate. The clinical outcomes of ICSI for oligozoospermic patients with Y chromosome AZF microdeletion are comparable to those of infertile patients with normal Y chromosomes. Our findings indicate that ICSI should be offered to patients with an AZFc deletion and that oligozoospermia patients with AZFb microdeletions are likely to father children.

Boar Differences In Artificial Insemination Outcomes: Can They Be Minimized?

In Western countries, where pig breeding and production are intensive, there is a documented variability in fertility between farms with boar-related parameters only accounting to 6% of this total variation of in vivo fertility. Such low boar effect could be a result of the rigorous control of sires and ejaculates yielding AI-doses exerted by the highly specialized AI-centres that monopolize the market. However, some subfertile boars pass through these rigorous controls and consequently reach the AI-programmes. Here, we discuss why testing young boars for chromosomal defects, sperm nuclear chromatin integrity and in vitro fertilizing ability can be discriminative and economically sound for removing these less fertile boars. Alongside, we discuss why boars differ in the ability of their sperm to tolerate cryopreservation or sex sorting.

Male Reproductive Disorders and Fertility Trends: Influences of Environment and Genetic Susceptibility

It is predicted that Japan and European Union will soon experience appreciable decreases in their populations due to persistently low total fertility rates (TFR) below replacement level (2.1 child per woman). In the United States, where TFR has also declined, there are ethnic differences. Caucasians have rates below replacement, while TFRs among African-Americans and Hispanics are higher. We review possible links between TFR and trends in a range of male reproductive problems, including testicular cancer, disorders of sex development, cryptorchidism, hypospadias, low testosterone levels, poor semen quality, childlessness, changed sex ratio, and increasing demand for assisted reproductive techniques. We present evidence that several adult male reproductive problems arise in utero and are signs of testicular dysgenesis syndrome (TDS). Although TDS might result from genetic mutations, recent evidence suggests that it most often is related to environmental exposures of the fetal testis. However, environmental factors can also affect the adult endocrine system. Based on our review of genetic and environmental factors, we conclude that environmental exposures arising from modern lifestyle, rather than genetics, are the most important factors in the observed trends. These environmental factors might act either directly or via epigenetic mechanisms. In the latter case, the effects of exposures might have an impact for several generations post-exposure. In conclusion, there is an urgent need to prioritize research in reproductive physiology and pathophysiology, particularly in highly industrialized countries facing decreasing populations. We highlight a number of topics that need attention by researchers in human physiology, pathophysiology, environmental health sciences, and demography.

XX testicular disorder of sex differentiation: case report

The 46 XX, testicular sex differentiation disorder, or XX male syndrome, is a rare condition detected by cytogenetics, in which testicular development occurs in the absence of the Y chromosome. It occurs in 1:20,000 to 25,000 male newborns and represents 2% of cases of male infertility. About 90% of individuals present with normal phenotype at birth and are generally diagnosed after puberty for hypoganadism, gynecomastia, and/or infertility. The authors present the report of an XX male with complete masculinization and infertility.

Molecular Dissection Using Array Comparative Genomic Hybridization and Clinical Evaluation of An Infertile Male Carrier of An Unbalanced Y;21 Translocation: A Case Report and Review of The Literature

Chromosomal defects are relatively frequent in infertile men however, translocations between the Y chromosome and autosomes are rare and less than 40 cases of Y-autosome translocation have been reported. In particular, only three individuals has been described with a Y;21 translocation, up to now. We report on an additional case of an infertile man in whom a Y;21 translocation was associated with the deletion of a large part of the Y chromosome long arm. Applying various techniques, including conventional cytogenetic procedures, fluorescence in situ hybridisation (FISH) analysis and array comparative genomic hybridization (array-CGH) studies, we identified a derivative chromosome originating from a fragment of the short arm of the chromosome Y translocated on the short arm of the 21 chromosome. The Y chromosome structural rearrangement resulted in the intactness of the entire short arm, including the sex-determining region Y (SRY) and the short stature homeobox (SHOX) loci, although translocated on the 21 chromosome, and the loss of a large part of the long arm of the Y chromosome, including azoospermia factor-a (AZFa), AZFb, AZFc and Yq heterochromatin regions. This is the first case in which a (Yp;21p) translocation has been ascertained using an array-CGH approach, thus reporting details of such a rearrangement at higher resolution.

Epigenetics and male reproduction: the consequences of paternal lifestyle on fertility, embryo development, and children lifetime health

The correlation between epigenetics and human reproduction represents a very interesting field of study, mainly due to the possible transgenerational effects related to epigenetic modifications of male and female gametes. In the present review, we focused our attention to the role played by epigenetics on male reproduction, evidencing at least four different levels at which sperm epigenetic modifications could affect reproduction: (1) spermatogenesis failure; (2) embryo development; (3) outcome of assisted reproduction technique (ART) protocols, mainly as concerning genomic imprinting; and (4) long-term effects during the offspring lifetime. The environmental agents responsible for epigenetic modifications are also examined, suggesting that the control of paternal lifestyle prior to conception could represent in the next future a novel hot topic in the management of human reproduction.

A PLK4 mutation causing azoospermia in a man with Sertoli cell-only syndrome

About 15% of couples wishing to have children are infertile; approximately half these cases involve a male factor. Polo-like kinase 4 (PLK-4) is a member of the polo protein family and a key regulator of centriole duplication. Male mice with a point mutation in the Plk4 gene show azoospermia associated with germ cell loss. Mutational analysis of 81 patients with azoospermia and Sertoli cell-only syndrome (SCOS) identified one man with a heterozygous 13-bp deletion in the Ser/Thr kinase domain of PLK4. Division of centrioles occurred in wild-type PLK4-transfected cells, but was hampered in PLK-4-mutant transfectants, which also showed abnormal nuclei. Thus, this PLK4 mutation might be a cause of human SCOS and nonobstructive azoospermia.

Male infertility and its genetic causes

AIM

Infertility is a serious social problem in advanced nations, with male factor infertility accounting for approximately half of all cases of infertility. Here, we aim to discuss our laboratory results in the context of recent literature on critical genes residing on the Y chromosome or autosomes that play important roles in human spermatogenesis.

METHODS

The PubMed database was systematically searched using the following keywords: 'genetics of male factor infertility'; 'male infertility genes', 'genetics of spermatogenesis' to retrieve information for this review.

RESULTS

Striking progress has recently been made in the elucidation of mechanisms of spermatogenesis using knockout mouse models. This information has, in many cases, not been directly translatable to humans. Nevertheless, mutations in several critical genes have been shown to cause male infertility. We discuss here the contribution to male factor infertility of a number of genes identified in the azoospermia factor (AZF) region on the Y chromosome, as well as the autosomally located genes: SYKP3, KLHL10, AURKC and SPATA16.

CONCLUSIONS

Non-obstructive azoospermia is the most severe form of azoospermia. However, the presence of spermatozoa can only be confirmed through procedures, which may prove to be unnecessary. Elucidation of the genes underlying male factor infertility, and thereby a better understanding of the mechanisms that cause it, will result in more tailored, evidence-based decisions in treatment of patients.

Bringing epigenetics into the diagnostics of the andrology laboratory: challenges and perspectives

Recent studies have shown significant associations of aberrant DNA methylation in spermatozoa with idiopathic male infertility, increased frequency of spontaneous abortions and imprinting disorders. Thus, the analysis of DNA methylation of specific genes in spermatozoa has the potential to become a new valuable diagnostic marker in clinical andrology. This perspective article discusses the current state and value of DNA methylation analysis in the diagnostic setup of infertile men and outlines challenges and perspectives. It highlights the potential of DNA methylation in andrological diagnostics and its putative benefit in the examination of hitherto idiopathic infertile patients is described.

Effects of increased paternal age on sperm quality, reproductive outcome and associated epigenetic risks to offspring

Over the last decade, there has been a significant increase in average paternal age when the first child is conceived, either due to increased life expectancy, widespread use of contraception, late marriages and other factors. While the effect of maternal ageing on fertilization and reproduction is well known and several studies have shown that women over 35 years have a higher risk of infertility, pregnancy complications, spontaneous abortion, congenital anomalies, and perinatal complications. The effect of paternal age on semen quality and reproductive function is controversial for several reasons. First, there is no universal definition for advanced paternal ageing. Secondly, the literature is full of studies with conflicting results, especially for the most common parameters tested. Advancing paternal age also has been associated with increased risk of genetic disease. Our exhaustive literature review has demonstrated negative effects on sperm quality and testicular functions with increasing paternal age. Epigenetics changes, DNA mutations along with chromosomal aneuploidies have been associated with increasing paternal age. In addition to increased risk of male infertility, paternal age has also been demonstrated to impact reproductive and fertility outcomes including a decrease in IVF/ICSI success rate and increasing rate of preterm birth. Increasing paternal age has shown to increase the incidence of different types of disorders like autism, schizophrenia, bipolar disorders, and childhood leukemia in the progeny. It is thereby essential to educate the infertile couples on the disturbing links between increased paternal age and rising disorders in their offspring, to better counsel them during their reproductive years.

LRGUK-1 is required for basal body and manchette function during spermatogenesis and male fertility

Male infertility affects at least 5% of reproductive age males. The most common pathology is a complex presentation of decreased sperm output and abnormal sperm shape and motility referred to as oligoasthenoteratospermia (OAT). For the majority of OAT men a precise diagnosis cannot be provided. Here we demonstrate that leucine-rich repeats and guanylate kinase-domain containing isoform 1 (LRGUK-1) is required for multiple aspects of sperm assembly, including acrosome attachment, sperm head shaping and the initiation of the axoneme growth to form the core of the sperm tail. Specifically, LRGUK-1 is required for basal body attachment to the plasma membrane, the appropriate formation of the sub-distal appendages, the extension of axoneme microtubules and for microtubule movement and organisation within the manchette. Manchette dysfunction leads to abnormal sperm head shaping. Several of these functions may be achieved in association with the LRGUK-1 binding partner HOOK2. Collectively, these data establish LRGUK-1 as a major determinant of microtubule structure within the male germ line.