Human male infertility and its genetic causes

Sperm retrieval rate and patient factors in azoospermia factor c microdeletion azoospermia: a systematic review

OBJECTIVE

To reveal the overall sperm retrieval rate (SRR) and range in patients with azoospermia factor c (AZFc) microdeletion azoospermia by microdissection testicular sperm extraction (mTESE) and discuss the differences of preoperative patient factors among studies with various SRRs.

PATIENTS AND METHODS

We searched PubMed, Web of Science and Embase until February 2023. All studies reporting SRRs by mTESE and required parameters of patients with AZFc microdeletions were included. The primary outcome was the SRR and, if available, the pregnancy rate (PR) and live-birth rate (LBR) after intracytoplasmic sperm injection were also investigated as secondary outcomes.

RESULTS

Eventually 11 cohort studies were included in this review. A total number of 441 patients underwent mTESE and in 275 of them sperm was obtained, reaching an overall SRR of 62.4%. The SRRs among studies had a wide range from 25.0% to 85.7%. The studies reporting higher SRRs generally had older mean ages, and higher follicle-stimulating hormone and testosterone levels. Only four studies provided practical data on pregnancies and live-born children of patients with AZFc microdeletions, so the overall PR and LBR were unavailable.

CONCLUSIONS

The overall SRR of patients with AZFc microdeletion azoospermia was 62.4%. The effect of patient factors in SR needs further evidence in future work.

Exploration of tissue fixation methods suitable for digital pathological studies of the testis

BACKGROUND

The way of testicular tissue fixation directly affects the correlation and structural integrity between connective tissue and seminiferous tubules, which is essential for the study of male reproductive development. This study aimed to find the optimal fixative and fixation time to produce high-quality testicular histopathological sections, and provided a suitable foundation for in-depth study of male reproductive development with digital pathology technology.

METHODS

Testes were removed from both sides of 25 male C57BL/6 mice. Samples were fixed in three different fixatives, 10% neutral buffered formalin (10% NBF), modified Davidson's fluid (mDF), and Bouin's Fluid (BF), for 8, 12, and 24 h, respectively. Hematoxylin and eosin (H&E) staining, periodic acid Schiff-hematoxylin (PAS-h) staining, and immunohistochemistry (IHC) were used to evaluate the testicle morphology, staging of mouse seminiferous tubules, and protein preservation. Aperio ScanScope CS2 panoramic scanning was used to perform quantitative analyses.

RESULTS

H&E staining showed 10% NBF resulted in an approximately 15-17% reduction in the thickness of seminiferous epithelium. BF and mDF provided excellent results when staining acrosomes with PAS-h. IHC staining of synaptonemal complexes 3 (Sycp3) was superior in mDF compared to BF-fixed samples. Fixation in mDF and BF improved testis tissue morphology compared to 10% NBF.

CONCLUSIONS

Quantitative analysis showed that BF exhibited a very low IHC staining efficiency and revealed that mouse testes fixed for 12 h with mDF, exhibited morphological details, excellent efficiency of PAS-h staining for seminiferous tubule staging, and IHC results. In addition, the morphological damage of testis was prolonged with the duration of fixation time.

Metabolomics of male infertility

This review explores the use of metabolomics in male infertility. Metabolomics, an evolving omics technology that targets the products of cellular metabolism, is valuable for elucidating underlying pathophysiology of many disorders including male infertility. The identification of reliable biomarkers is essential for accurate diagnosis and for developing precision therapeutics for those afflicted by reproductive dysfunction. Unfortunately, despite significant progress to date, the intricate relationships between these metabolic pathways and male infertility remain elusive. It is clear, however, that additional research is required to more fully characterize the role of metabolomics in this disorder and in the potential development of targeted therapies for precision medicine.

Subfertility as Overlapping of Nutritional, Endocrine, Immune, and Cardiometabolic Dysregulations-A Study Focused on Biochemical Endophenotypes of Subfertile Couples

Subfertility is a global health issue, and as many as 30% of cases are attributed to unexplained reasons. A hypercaloric, high-fat diet stimulates the expansion of pro-inflammatory gut microbiota with a consequent rise in circulating lipopolysaccharides. Adverse gut microbiota remodeling can exacerbate insulin resistance, while sex and thyroid hormones may influence the variability in gut microbiota. This cross-sectional study included 150 participants and was designed to determine a biochemical, nutritional-related pattern that may distinguish subfertile from fertile individuals and couples. A panel of 28 biomarkers was assessed. Four biochemical phenotypes of unexplained subfertility were found, including two metabolic and two immune, when assessed using binary logistic regression models. Two phenotypes were distinguished in women: cardio-metabolic with atherogenic dyslipidemia (LowHDL-cholesterol: OR = 10.9; p < 0.05) and autoimmune thyroid disorder (Highanti-thyroid-peroxidase: OR = 5.5; p < 0.05) and two in men: hepato-metabolic with elevated liver injury enzymes (HighHOMA-IR: OR = 6.1; p < 0.05) and immune type-2 response (HighIgE: OR = 6.4; p < 0.05). The chances of a couple's subfertility rose with the number of laboratory components of metabolic syndrome in the couple (OR = 1.7; p < 0.05) and if at least one partner had an elevated total IgE level (>100 kU/L) (OR = 6.5; p < 0.05). This study found that unexplained subfertility may be accompanied by mutually overlapping immune and metabolic dysregulations in individuals and couples. We propose one-time laboratory diagnostics taking into account the lipid profile, insulin resistance, anti-thyroid-peroxidase, and total IgE in both males and females with unexplained subfertility. This may allow for a one-time assessment of targeted medical and nutritional interventions and help optimize patients' health. The gut-organ axes related to subfertility are discussed in the context of the obtained results.

Evaluation of Predicting Factors Affecting Sperm Retrieval in Patients with Klinefelter Syndrome: A Prospective Study

BACKGROUND

This study aimed to evaluate the predicting factors affecting sperm retrieval. We prospectively assessed the relationship between sonographic and microdissection testicular sperm extraction (mTESE) findings in Klinefelter syndrome (KS).

MATERIALS AND METHODS

In this prospective study, 44 azoospermic men with 47, XXY karyotypes participated in this study. In order to evaluate the amount of blood supply in different parts of testicular tissue, a doppler ultra-sonographic was performed. Also, for the detection of sperm in this group mTESE technique was performed.

RESULTS

The age average of positive mTESE and negative mTESE groups was 29.4 and 33.6 years, respectively. By comparing the testicle volume (based on the data obtained from the clinical examinations conducted by the urologist) it was determined that there is no significant difference between mTESE positive and negative groups. Folliclestimulating hormone (FSH) levels in men with negative mTESE (P=0.03) and testosterone levels in men with positive mTESE significantly increased (P=0.017). The overall rate of testis vascularity was significantly higher in the positive mTESE group than in the negative mTESE group. The clinical pregnancy rate in positive mTESE men was 9% per cycle, 16.6% per embryos were transferred (ET), and 12.5% per cycle.

CONCLUSION

Totally, our observation indicated that there is not a significant relationship between sonographic and mTESE results in KS patients. However, more investigations with bigger sample Size can be useful to validate our results.

Is sperm telomere length altered in teratozoospermia specimens? A case-control study

Background

Male factor infertility is a multifactorial defect, and many of its etiologies are unknown. Teratozoospermia is determined by the existence of over 85% morphologically abnormal spermatozoa in semen which are almost incompetent in fertilization function. One of the most novel issues in genetic alterations studies is the variation of sperm telomere lengths (STL) and its collaboration with male infertility. The present study has been focused on STL alterations in teratozoospermia.

Objective

Investigation of differences in telomere length of teratozoospermia specimens and sperms with normal parameters.

Materials and Methods

In this case-control study, 60 men referred to Arak Fertility Clinic, Markazi province, Iran from November 2017 to February 2018 were categorized into teratozoospermia and normozoospermic groups. Sperm genomic DNA extraction was conducted, and STL were evaluated using quantitative polymerase chain reaction.

Results

Statistical evaluation of relative telomere length was calculated by the ratio of telomere to single-copy gene for teratozoospermia and normal specimens. Results significantly demonstrated that relative telomere length in teratozoospermia samples is nearly 3 times shorter than in normal samples (p > 0.001).

Conclusion

Our results represent the reduction of telomeres length in teratozoospermia and suggest that this alteration might be one of the factors contributing to the sperm fertility potential of this kind of specimen. However, defining relevant molecular processes requires further detailed investigations.

A Three-Year Prospective Study Assessing the Application of Chromosomal Microarray Analysis in 576 High-Risk Pregnant Women

Background

The use of chromosomal microarray analysis (CMA) in prenatal diagnosis of chromosomal and genetic diseases has resulted in a significant improvement in the diagnosis of genetically caused congenital malformations, neurodevelopmental disorders, and congenital anomalies, with a high diagnostic yield in selected prenatal cases.

Objective

The objective of this study was to evaluate the application of CMA in the prenatal diagnosis of high-risk pregnant women.

Method

A total of 576 pregnancies were selected from May 2018 to October 2020 in our hospital, including amniotic fluid chromosome, karyotype analysis, and CMA detection. The study group was divided into two groups based on the indications for testing: group A has 88 patients at the age of 35 years or older, and group B patients were in high-risk pregnancies, which consisted of 33 cases of bad pregnancy history, 252 high-risk serological screenings, 70 high-risk non-invasive prenatal testing (NIPT), 65 cases of B-ultrasound indicated fetal development abnormalities or ultrasonic soft marker abnormalities, and 68 other cases of pregnant women or both who have genetic or chromosomal abnormalities. At last, we have an analysis of the detection rate from different testing methods.

Results

Based on the follow-up test, 576 high-risk pregnant women showed an amniotic fluid chromosome karyotype rate of 18.1% (104/576), and the remaining 472 of these cases suffered a CNV ratio of 14.2% (67/472). 472 women of low clinical relevance are at 4.87% (23/472), 16 people showed a clear cause ratio = 3.39% (16/472), and 28 of the 472 (5.93%) cases showed polymorphism.

Conclusions

In our study, CMA significantly improved the fetal detection rate and diagnosis rate in high-risk pregnant women, which proved to be a very useful method in the diagnosis of genetically caused neurodevelopmental disorders and congenital anomalies. The use of CMA in high-risk pregnant women is justified, and these women can detect an additional (3.40%, 16/472) of pathogenic microdeletions and microduplications in the cases.

lncRNA 1700101O22Rik and NONMMUG030480.1 Are Not Essential for Spermatogenesis in Mice

Many testis-specific lncRNAs are highly expressed in late spermatogenesis, especially in spermiogenesis. However, their functions and the underlying mechanisms in male fertility are largely unknown. Here, we screened two highly expressed lncRNAs, 1700101O22Rik (O22Rik) and NONMMUG030480.1 (NM480) in testes, to investigate the roles in spermatogenesis using lncRNA knockout (KO) mouse generated by CRISPER/Cas9 technology. Both testis-specific lncRNAs were mainly expressed from secondary spermatocytes to round spermatids, suggesting that they might be involved in spermiogenesis. Phenotypic analysis showed that the deletion of O22Rik or NM480 did not affect the development of testis and epididymis or spermatogenesis. These results were confirmed in both young and middle-aged male mice. In addition, there was no significant difference in sperm morphology and other parameters including concentration and motility between wild type (WT) and KO mice. Fertility tests showed that litter size was significantly lower in O22Rik KO mice compared with WT controls. Although O22Rik did not exert dramatic roles in spermatogenesis, on molecular levels, its surrounding gene expression was disturbed significantly. Gm32773 was decreased; however, Gm32828 was increased in KO mice. In conclusion, lncRNA O22Rik and NM480 are not individually essential for spermatogenesis in mice.

miR-188-3p-targeted regulation of ATG7 affects cell autophagy in patients with nonobstructive azoospermia

BACKGROUND

Nonobstructive azoospermia (NOA) is one of the most difficult forms of male infertility to treat, and its pathogenesis is still unclear. miRNAs can regulate autophagy by affecting their target gene expression. Our previous study found that miR-188-3p expression in NOA patients was low. There are potential binding sites between the autophagy gene ATG7 and miR-188-3p. This study aimed to verify the binding site between miR-188-3p and ATG7 and whether miR-188-3p affects autophagy and participates in NOA by regulating ATG7 to influence the autophagy marker genes LC3 and Beclin-1.

METHODS

Testicular tissue from 16 NOA patients and 16 patients with normal spermatogenesis and 5 cases in each group of pathological sections were collected. High-throughput sequencing was performed to detect mRNA expression differences. Quantitative real-time polymerase chain reaction (qRT-PCR), Western blotting, immunohistochemical staining and immunofluorescence were used to detect protein localization and expression. Autophagosome changes were detected by electron microscopy. The targeting relationship between miR-188-3p and ATG7 was confirmed by a luciferase assay.

RESULTS

ATG7 protein was localized in the cytoplasm of spermatogenic cells at all levels, and the ATG7 gene (p = 0.019) and protein (p = 0.000) were more highly expressed in the NOA group. ATG7 expression after overexpression/inhibition of miR-188-3p was significantly lower (p = 0.029)/higher (p = 0.021) than in the control group. After overexpression of miR-188-3p, the ATG7 3'UTR-WT luciferase activity was impeded (p = 0.004), while the ATG7 3'UTR-MUT luciferase activity showed no significant difference (p = 0.46). LC3 (p = 0.023) and Beclin-1 (p = 0.041) expression in the NOA group was significantly higher. LC3 and Beclin-1 gene expression after miR-188-3p overexpression/inhibition was significantly lower (p = 0.010 and 0.024, respectively) and higher (p = 0.024 and 0.049, respectively). LC3 punctate aggregation in the cytoplasm decreased after overexpression of miR-188-3p, while the LC3 punctate aggregation in the miR-188-3p inhibitor group was higher. The number of autophagosomes in the miR-188-3p mimic group was lower than the number of autophagosomes in the mimic NC group.

CONCLUSIONS

LC3 and Beclin-1 were more highly expressed in NOA testes and negatively correlated with the expression of miR-188-3p, suggesting that miR-188-3p may be involved in the process of autophagy in NOA. miR-188-3p may regulate its target gene ATG7 to participate in autophagy anDual luciferase experiment d affect the development of NOA.

Target-Sequencing of Female Infertility Pathogenic Gene Panel and a Novel TUBB8 Loss-of-Function Mutation

Genetic screening is an important approach for etiology determination and helps to optimize administration protocols in reproductive centers. After the first pathogenic gene of female infertility was reported in 2016, more and more new pathogenic genes were discovered, and we sought to develop an efficient and cost-effective method for genetic screening in patients. In this study, we designed a target-sequencing panel with 22 female infertility-related genes, namely, TUBB8, PATL2, WEE2, and PANX1 and sequenced 68 primary infertility (PI) and recurrent pregnancy loss (RPL) patients. We sequenced 68 samples reaching an average depth of 1559× and detected 3,134 variants. Among them, 62.2% were synonymous single-nucleotide variants (SNVs) and 36.3% were non-synonymous SNVs. The remaining 1.5% are indels (insertions and deletions) and stop-gains. DNAH11 and TUBB8 are the two genes that mutated most frequently. We also found a novel TUBB8 variant (c.898_900del; p.300_300del), proved its loss-of-function mechanism, and profiled the interactome of the wild-type (WT) and mutant TUBB8 proteins. Overall, this target-sequencing method provides an efficient and cost-effective approach for screening in IVF clinics and will support researchers for the discovery of new pathogenic variants.

Microenvironment for spermatogenesis and sperm maturation

The male reproductive system consists of testes, a series of ducts connecting the testes to the external urethral orifice, accessory sex glands, and the penis. Spermatogonial stem cells differentiate and mature in testes and epididymides, and spermatozoa are ejaculated with exocrine fluids secreted by accessory sex glands. Many studies have clarified the detailed structure and function of the male reproductive system, and have shown that various biologic controls, including genomics, epigenetics, and the neuroendocrine-immune system regulate proliferation, differentiation, and maturation of germ cells. In other words (1) genetic deletion or abnormalities, (2) aberration of DNA methylation and histone modifications, as well as small RNA dysfunction, and (3) neuroendocrine-immune disorders are involved in functional failure of the male reproductive system. In this article, we review these three factors for germ cell microcircumstance, especially focused on the immunoendocrine environment. In particular, the relation between factors protecting germ cells with strong auto-immunogenicity and opposite factors compromising this protection are discussed. Reductions in sperm count, concentration, and semen quality are serious problems in developed countries, although the causes are complex and remain unclear. The accumulation of basic knowledge regarding the structure, function, and regulation of the male reproductive system under various experimental conditions will be important to resolve these problems.

Novel exon mutation in SYCE1 gene is associated with non-obstructive azoospermia

Non‐obstructive azoospermia (NOA) is a common cause of male infertility, and genetic problems, such as chromosomal abnormalities and gene mutations, are important causes of NOA. Our centre received a case of NOA, in which no mature sperm was found during microdissection testicular sperm extraction. A postoperative pathological examination revealed that testicular spermatogenesis was blocked. Target region capture combined with high‐throughput sequencing was used to screen for male infertility‐related gene mutations. Sanger sequencing further confirmed that the SYCE1 gene, a central component of the synaptonemal complex (SC) during meiosis, had a homozygous deletion mutation in the tenth exon (c.689_690del; p.F230fs). Through molecular biological studies, we discovered altered expression and nuclear localization of the endogenous mutant SYCE1. To verify the effects in vitro, wild‐ and mutated‐type SYCE1 vectors were constructed and transfected into a human cell line. The results showed that the expression and molecular weight were decreased for SYCE1 containing c.689_690del. In addition, mutated SYCE1 was abnormally located in the cytoplasm rather than in the nucleus. In summary, our research suggests that the novel homozygous mutation (c.689_690del; p.F230fs) altered the SYCE1 expression pattern and may have disturbed SC assembly, leading to male infertility and to a barrier to gamete formation. We reported for the first time that a frameshift mutation occurred in the exon region of SYCE1 in an NOA patient. This study is beneficial for accurate NOA diagnosis and the development of corresponding gene therapy strategies.

The Sixth Edition of the WHO Manual for Human Semen Analysis: A Critical Review and SWOT Analysis

Semen analysis is the cornerstone of male fertility evaluation with WHO guidelines providing the basis for procedural standardization and reference values worldwide. The first WHO manual was published in 1980, and five editions have been subsequently released over the last four decades. The 6th Edition was published in July 2021. In this review, we identify the key changes of this 6th Edition. Additionally, we evaluate the utility of this 6th Edition in clinical practice using SWOT (strengths, weaknesses, opportunities, and threats) analysis. This new Edition has made the analysis of basic semen parameters more robust, taking into account the criticisms and grey areas of the previous editions. The tests assessing sperm DNA fragmentation and seminal oxidative stress are well-described. The main novelty is that this latest edition abandons the notion of reference thresholds, suggesting instead to replace them with “decision limits”. While this seems attractive, no decision limits are proposed for either basic semen parameters, or for extended or advanced parameters. This critical review of the 6th Edition of the WHO laboratory manual combined with a SWOT analysis summarizes the changes and novelties present in this new Edition and provides an in-depth analysis that could help its global use in the coming years.

Protective effects of Lepidium draba L. leaves extract on testis histopathology, oxidative stress indicators, serum reproductive hormones and inflammatory signalling in oxymetholone-treated rat

This study was aimed to investigate the protective effects of Lepidium draba L. (L. draba) extract on oxymetholone (OM)-induced testicular injury in rat. Six groups of n = 5 adult male rats were used as; 1: control, 2: OM (5 mg/kg OM orally), 3, 4 and 5: L. draba extract (100, 200 and 400 mg kg^-1  day^-1 ) +OM (5 mg kg^-1  day^-1 OM) and 6:400 mg/kg/d L. draba extract for 30 days. Serum testosterone (T), follicle-stimulating hormone (FSH) and luteinising hormone (LH), inflammatory cytokines (IL-6, IL-10, TNF-α, IL-1β), oxidative stress (OS) indicators [superoxide dismutase, catalase, glutathione peroxidase and nitric oxide (NO)], apoptotic related genes (Bcl-2, p53, caspase-3 (c3) and Bax) were investigated. OM significantly increased the serum levels of T, proinflammatory cytokines and pro-apoptotic genes expression. Also, it decreased LH and FSH, sperm viability, count and motility. L. draba extract especially could markedly normalise the serum levels of LH and FSH, and T, restore serum antioxidant enzymes and suppressed the pro-inflammatory cytokines. Also, germ cells apoptosis was inhibited against via downregulating the p53, c3, Bax and upregulating Bcl-2. It concluded that L. draba extract could protect the function and structure of testis against OM-induced testicular toxicity via its antioxidant and anti-inflammatory properties.

Gene Alterations and Expression Spectrum of NANOS3 in Nonobstructive Azoospermia

Nanos3, a zinc finger RNA-binding protein, suppresses the apoptosis in primordial germ cells (PGCs) during migration to gonads and maintains the PGC population. The genetic variations and expression of NANOS3 in patients with non-obstructive azoospermia (NOA) were evaluated in this study. The study included 100 idiopathic infertile men with NOA and 100 fertile men as the as the case and control groups, respectively. NANOS3 gene variations were analyzed using the standard polymerase chain reaction (PCR) and sequencing. For mRNA and protein expression analysis, testicular biopsy specimens from 27 patients including 9 obstructive azoospermia (OA), 9 maturation arrest (MA), and 9 Sertoli cell-only syndromes (SCOS) were collected and evaluated using the real-time PCR technique and immunohistochemistry. Although the evaluation of the 5`UTR regulatory region has shown the significant difference in the numbers of TG repeats in rs11182456 between groups, the odd ratio was not strong enough to consider that as a certain risk factor lead to azoospermia and infertility. Meanwhile, NANOS3 expression at mRNA level had a significant difference among OA, SCOS, and MA groups.

Role of laminin and collagen chains in human spermatogenesis - Insights from studies in rodents and scRNA-Seq transcriptome profiling

Studies have demonstrated that biologically active fragments are generated from the basement membrane and the Sertoli cell-spermatid adhesion site known as apical ectoplasmic specialization (apical ES, a testis-specific actin-based anchoring junction) in the rat testis. These bioactive fragments or peptides are produced locally across the seminiferous epithelium through proteolytic cleavage of constituent proteins at the basement membrane and the apical ES. Studies have shown that they are being used to modulate and coordinate cellular functions across the seminiferous epithelium during different stages of the epithelial cycle of spermatogenesis. In this review, we briefly summarize recent findings based on studies using rat testes as a study model regarding the role of these bioactive peptides that serve as a local regulatory network to support spermatogenesis. We also used scRNA-Seq transcriptome datasets in the public domain for OA (obstructive azoospermia) and NAO (non-obstructive azoospermia) human testes versus testes from normal men for analysis in this review. It was shown that there are differential expression of different collagen chains and laminin chains in these testes, suggesting the possibility of a similar local regulatory network in the human testis to support spermatogenesis, and the possible disruption of such network in men is associated with OA and/or NOA.

Mesenchymal Stem Cells in Preclinical Infertility Cytotherapy: A Retrospective Review

Infertility is a global reproductive disorder which is caused by a variety of complex diseases. Infertility affects the individual, family, and community through physical, psychological, social and economic consequences. The results from recent preclinical studies regarding stem cell-based therapies are promising. Stem cell-based therapies cast a new hope for infertility treatment as a replacement or regeneration strategy. The main features and application prospects of mesenchymal stem cells in the future of infertility should be understood by clinicians. Mesenchymal stem cells (MSCs) are multipotent stem cells with abundant source, active proliferation, and multidirectional differentiation potential. MSCs play a role through cell homing, secretion of active factors, and participation in immune regulation. Another advantage is that, compared with embryonic stem cells, there are fewer ethical factors involved in the application of MSCs. However, a number of questions remain to be answered prior to safe and effective clinical application. In this review, we summarized the recent status of MSCs in the application of the diseases related to or may cause to infertility and suggest a possible direction for future cytotherapy to infertility.

[Testicular sperm extraction in male infertility : Indications, success rates, practical implementation, and possible complications]

BACKGROUND

Unwanted childlessness is a burden on a couple's relationship. The therapeutic spectrum of male infertility has increased significantly in recent years so that even azoospermia patients can be given biological paternity by testicular sperm extraction (TESE).

OBJECTIVES

The indications, success rates, practical implementation, and possible complications of conventional and microscopic TESE in male infertility are presented in this review.

METHODS

A nonsystematic search of the relevant literature was carried out.

RESULTS

In obstructive azoospermia (OA), primarily desobstructive surgical procedures are used, while TESE is the surgical procedure of choice in nonobstructive azoospermia (NOA). In the latter, sperm extraction can be performed conventionally or microscopically (mTESE) assisted, whereby the latter offers an advantage in terms of sperm detection rate in the case of small testicular volumes (<12 ml), chemotherapy, Klinefelter's disease and AZFc microdeletions. The sperm detection rate of TESE is about 50%. Postoperative controls are useful because of the possible induction of symptomatic hypogonadism.

CONCLUSION

Before performing TESE, determining the hormone status and human genetic clarification are necessary. Any costs incurred and the possibility of missing sperm proof must be discussed. Close cooperation between andrologists, gynecologists, reproductive physicians, and human geneticists is necessary. All in all, TESE is a safe surgical procedure with a low complication rate.

Histology and sperm retrieval among men with Y chromosome microdeletions

In this review of Y chromosome microdeletions, azoospermia factor (AZF) deletion subtypes, histological features and microTESE sperm retrieval rates are summarized after a systematic literature review. PubMed was searched and papers were identified using Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Approximately half of infertile couples have a male factor contributing to their infertility. One of the most common genetic etiologies are Y chromosome microdeletions. Men with Y chromosome microdeletions may have rare sperm available in the ejaculate or undergo surgical sperm retrieval and subsequent intracytoplasmic sperm injection to produce offspring. Azoospermia or severe oligozoospermia are the most common semen analysis findings found in men with Y chromosome microdeletions, associated with impaired spermatogenesis. Men with complete deletions of azoospermia factor a, b, or a combination of any loci have severely impaired spermatogenesis and are nearly always azoospermic with no sperm retrievable from the testis. Deletions of the azoospermia factor c or d often have sperm production and the highest likelihood of a successful sperm retrieval. In men with AZFc deletions, histologically, 46% of men demonstrate Sertoli cell only syndrome on biopsy, whereas 38.2% have maturation arrest and 15.7% have hypospermatogenesis. The microTESE sperm retrieval rates in AZFc-deleted men range from 13-100% based on the 32 studies analyzed, with a mean sperm retrieval rate of 47%.

A comparative study of transabdominal and transvaginal ultrasound guidance on consequences of embryo transfer at Mahdiyeh hospital of Tehran in 2020: An RCT

Background

Infertility is an important problem that affects many couples worldwide. Assisted reproductive technology (ART) helps infertile couples to have offspring. One of the critical parts of ART is embryo transfer (ET).

Objective

To compare the effect of transvaginal and transabdominal ultrasonography-guided ET on ART outcomes.

Materials and Methods

In this randomized clinical trial study, 90 women who were candidates for in vitro fertilization (IVF) referred to Mahdiyeh hospital of Tehran, Iran during the yr 2020 were randomly divided into two groups (n = 45/each) of transvaginal and transabdominal ultrasonography-guided ET. The embryos were transferred two-three days after oocyte retrieval. The patient pain, duration and difficulty of the procedure, three-dimensional vision quality and successful pregnancy rate were measured.

Results

In this study, 63.2% of the 45 women who underwent IVF under the guidance of the transvaginal guidance and 36.8% of the 45 women who underwent IVF under the transabdominal guidance had a successful pregnancy, which was not significantly different (p = 0.19). Also, based on other results there was no difference between the two groups in terms of patient pain (p = 0.53), duration (p ≥ 0.50), difficulty of procedures (p ≥ 0.50) and ultrasonography vision; however, the three-dimensional vision quality in the transvaginal ultrasonography was better than that in the transabdominal ultrasonography (p < 0.01).

Conclusion

Overall, the ART outcomes in the transvaginal and transabdominal ultrasonography-guided ET were similar, so we suggest that physicians evaluate the patient's situation, the hospital equipment, and their ability before selecting the type of ultrasonography.

SCF Improves In Vitro Differentiation of SSCs Through Transcriptionally Up-regulating PRTM1, STRA8, c-KIT, PIWIL2, and OCT4 Genes

Several lines of evidence strongly suggest that retinoic acid (RA) and stem cell factor (SCF)/c-Kit signal transduction pathways are involved in the differentiation of spermatogonial stem cells (SSCs). This study was aimed to investigate the effect of RA and SCF on in vitro differentiation of SSCs via evaluation of the mRNA expression of meiosis-specific genes in cultured testicular tissues. Testicular tissue samples were obtained from bilaterally vasectomized rats and also healthy adult rats and then were cultured for 25, 30, and 35 days on different conditions. The cultured testicular pieces were sectioned and stained with PAS to histological analysis. The total RNA was extracted from cultured testicular samples, and the expression of ACR, PRTM1, SYCP3, STRA8, c-KIT, PIWIL2, and OCT4 genes at mRNA level was quantified using real-time polymerase chain reaction (qPCR) procedure. After 1-month surgery, bilateral testicular weight showed a significant decrease in vasectomized adult rats compared with healthy adult rats (P < 0.05). Reduction in the diameter of the seminiferous tubules and depletion of advanced germinal elements in vasectomized rats compared with healthy adult rats were also observed. Our findings also demonstrated that the mRNA expression level of PRTM1, STRA8, c-KIT, PIWIL2, and OCT4 genes in cultured testicular tissues significantly up-regulated in experimental group II compared with the control group (P < 0.001). Our findings lead us to conclude that SCF improves in vitro differentiation of SSCs in the OA rats, at least partially, by transcriptionally upregulating PRTM1, STRA8, c-KIT, PIWIL2, and OCT4 genes.

Integrative bioinformatics approaches for identifying potential biomarkers and pathways involved in non-obstructive azoospermia

Background

Non-obstructive azoospermia (NOA) is a disease related to spermatogenic disorders. Currently, the specific etiological mechanism of NOA is unclear. This study aimed to use integrated bioinformatics to screen biomarkers and pathways involved in NOA and reveal their potential molecular mechanisms.

Methods

GSE145467 and GSE108886 gene expression profiles were obtained from the Gene Expression Omnibus (GEO) database. The differentially expressed genes (DEGs) between NOA tissues and matched obstructive azoospermia (OA) tissues were identified using the GEO2R tool. Common DEGs in the two datasets were screened out by the VennDiagram package. For the functional annotation of common DEGs, DAVID v.6.8 was used to perform Gene Ontology (GO) and the Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis. In accordance with data collected from the Search Tool for the Retrieval of Interacting Genes/Proteins (STRING) database, a protein–protein interaction (PPI) network was constructed by Cytoscape. Cytohubba in Cytoscape was used to screen the hub genes. Furthermore, the hub genes were validated based on a separate dataset, GSE9210. Finally, potential micro RNAs (miRNAs) of hub genes were predicted by miRWalk 3.0.

Results

A total of 816 common DEGs, including 52 common upregulated and 764 common downregulated genes in two datasets, were screened out. Some of the more important of these pathways, including focal adhesion, PI3K-Akt signaling pathway, cell cycle, oocyte meiosis, AMP-activated protein kinase (AMPK) signaling pathway, FoxO signaling pathway, and Huntington disease, were involved in spermatogenesis. We further identified the top 20 hub genes from the PPI network, including CCNB2, DYNLL2, HMMR, NEK2, KIF15, DLGAP5, NUF2, TTK, PLK4, PTTG1, PBK, CEP55, CDKN3, CDC25C, MCM4, DNAI1, TYMS, PPP2R1B, DNAI2, and DYNLRB2, which were all downregulated genes. In addition, potential miRNAs of hub genes, including hsa-miR-3666, hsa-miR-130b-3p, hsa-miR-15b-5p, hsa-miR-6838-5p, and hsa-miR-195-5p, were screened out.

Conclusions

Taken together, the identification of the above hub genes, miRNAs and pathways will help us better understand the mechanisms associated with NOA, and provide potential biomarkers and therapeutic targets for NOA.

Genes predisposing to syndromic and nonsyndromic infertility: a narrative review

Background

Advanced biological techniques have helped produce more insightful findings on the genetic etiology of infertility that may lead to better management of the condition. This review provides an update on genes predisposing to syndromic and nonsyndromic infertility.

Main body

The review identified 65 genes linked with infertility and infertility-related disorders. These genes regulate fertility. However, mutational loss of the functions of the genes predisposes to infertility. Twenty-three (23) genes representing 35% were linked with syndromic infertility, while 42 genes (65%) cause nonsyndromic infertility. Of the 42 nonsyndromic genes, 26 predispose to spermatogenic failure and sperm morphological abnormalities, 11 cause ovarian failures, and 5 cause sex reversal and puberty delay. Overall, 31 genes (48%) predispose to male infertility, 15 genes (23%) cause female infertility, and 19 genes (29%) predispose to both. The common feature of male infertility was spermatogenic failure and sperm morphology abnormalities, while ovarian failure has been the most frequently reported among infertile females. The mechanisms leading to these pathologies are gene-specific, which, if targeted in the affected, may lead to improved treatment.

Conclusions

Mutational loss of the functions of some genes involved in the development and maintenance of fertility may predispose to syndromic or nonsyndromic infertility via gene-specific mechanisms. A treatment procedure that targets the affected gene(s) in individuals expressing infertility may lead to improved treatment.

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.

Over-expression of hsa_circ_0000116 in patients with non-obstructive azoospermia and its predictive value in testicular sperm retrieval

BACKGROUND

Non-obstructive azoospermia (NOA), identified in approximately 10% of infertile males, is a multifactorial disease whose molecular mechanisms remain unknown.

OBJECTIVES

The aim of this study was to identify the role of hsa_circ_0000116 in NOA and illustrate its predictive value in testicular sperm retrieval.

MATERIALS AND METHODS

The study included 78 individuals, 58 with NOA and 20 with obstructive azoospermia (OA). Serum hormones including testosterone (T), follicle-stimulating hormone (FSH), luteinizing hormone (LH), prolactin (PRL), and estradiol II (E2) were measured. Testicular histopathology was analyzed by at least two pathologists. The expression of hsa_circ_0000116 in testicular tissue samples was detected using real-time PCR, and the circRNA-miRNA-mRNA networks were predicted using bioinformatics analysis.

RESULTS

Our study illustrated that the expression of hsa_circ_0000116 was significantly higher in testicular tissue samples of NOA patients than in that of OA patients. Moreover, hsa_circ_0000116 was aberrantly expressed in three different pathological types of NOA: It was significantly up-regulated in patients with Sertoli cell-only syndrome (SCOS) when compared to patients with hypospermatogenesis (HS). In addition, the expression of hsa_circ_0000116 was negatively correlated with Johnsen score, while it was positively correlated with serum FSH level. A multivariate logistic regression model demonstrated that a high level of hsa_circ_0000116 was associated with a low rate of successful testicular sperm retrieval. Bioinformatics analysis and verification experiments showed that one of the most probable potential target miRNA for hsa_circ_0000116 was hsa-miR-449a. Further analysis indicated that hsa_circ_0000116 may be affecting the fertility function through a hsa_circ_0000116-miR-449-autophagy-related competing endogenous RNA (ceRNA) network.

DISCUSSION AND CONCLUSION

We report for the first time that hsa_circ_0000116 may play pivotal roles in regulating spermatogenesis and may also be a potential biomarker for the diagnosis and treatment of NOA, while acting as a predictive tool for the rate of successful testicular sperm retrieval in NOA patients.

Case report: A non-obstructive azoospermia patient with heat shock factor-2 mutation

RATIONALE

Infertility is a common medical condition that affects nearly 15% of the world population. Non-obstructive azoospermia (NOA) is one of the most severe forms of male infertility. Some common structural variants, single nucleotide polymorphisms (SNPs), and genetic factors were reported to be associated with NOA. However, the underlying etiology and genetic mechanism(s) remain largely unclear. This report aimed to describe the associated mutation of the heat shock factor-2 (HSF2) gene in Chinese infertile men with NOA.

PATIENT CONCERNS

An apparently healthy 27-year-old man with a body mass index (BMI) of 23.31 kg/m had a 2-year history of primary infertility.

DIAGNOSES

The semen analysis of the patient showed a sperm concentration of 0/mL in 6.5 mL of semen. The patient was diagnosed with NOA by performing the comprehensive examinations including a detailed medical history, physical examination, chromosome analysis, Y-chromosome microdeletions, semen analysis, and hormone profiles.

INTERVENTIONS

The couple received artificial insemination by donor (AID) and a healthy girl was born after the embryo transfer.

OUTCOMES

We found a novel deletion-insertion variation c.326_326delinsGGAAGGTGAGCTATTGT in the exon 3 of the HSF2 gene by performing next-generation sequencing on him who was diagnosed NOA. We performed Sanger sequencing on this patient and confirmed the heterozygous missing insertion mutation in the patient. This is a novel mutation. The variant was heterozygous and categorized as pathogenic.

LESSONS

A novel deletion-insertion variation c.326_326delinsGGAAGGTGAGCTATTGT in the exon 3 of HSF2 gene HSF2 is predicted to be pathogenic and associated with the occurrence of NOA.

Association between X-ray repair cross-complementing group 1 Arg399Gln polymorphism and male infertility: An update meta-analysis

Numerous studies concentrate on the association between X-ray repair cross-complementing group 1 (XRCC1) gene polymorphism and male infertility; however, the results remain inconclusive and inconsistent. Hence, this meta-analysis was conducted to get a precise estimation of the correlation. PubMed, Web of Science, Embase, Scopus and China National Knowledge Infrastructure (CNKI) databases were searched to identify the all relevant studies before 3 May 2020. Summary odds ratios (ORs) and 95% confidence intervals (95% CIs) were used to assess the strength of the association. Finally, six studies with 1,886 cases and 1,212 controls were included in our study. The result indicated that XRCC1 Arg399Gln polymorphism was significantly associated with male infertility under allelic model (A-allele vs. G-allele: OR = 1.183, p = .003), heterozygote genetic model (AA vs. GA: OR = 1.256, p = .027), recessive genetic model (AA vs. GG + GA: OR = 1.279, p = .012) and dominant genetic model (AA + GA vs. GG: OR = 1.218, p = .026). In addition, in Asian subgroup, statistic correlation remained significant in allelic model (A-allele vs. G-allele: OR = 1.145, p = .025) with rare heterogeneity (I²  = 0%). In summary, our meta-analysis suggested that XRCC1 Arg399Gln polymorphism was significantly associated with male infertility and the A-allele might be a risk factor for this disease, especially in Asians.

Genetic aspects of idiopathic asthenozoospermia as a cause of male infertility

Infertility is a worldwide problem affecting about 15% of couples trying to conceive. Asthenozoospermia (AZS) is one of the major causes of male infertility, diagnosed by reduced sperm motility, and has no effective therapeutic treatment. To date, a few genes have been found to be associated with AZS in humans and mice, but in most of cases its molecular aetiology remains unknown. Genetic causes of AZS may include chromosomal abnormalities, specific mutations of nuclear and mitochondrial genes. However recently, epigenetic factors, altered microRNAs expression signature, and proteomics have shed light on the pathophysiological basis of AZS. This review article summarises the reported genetic causes of AZS.

Diagnostic value of routine semen analysis in clinical andrology

Infertility is a major health issue affecting over 48.5 million couples around the world, with the male factor accounting for about 50% of the cases. The conventional semen analysis recommended by the World Health Organization (WHO) is the cornerstone in the evaluation of male fertility status. It includes macroscopic and microscopic evaluation of the ejaculate, which reflects the production of spermatozoa in the testes, the patency of the duct system and the glandular secretory activity. Evaluation of seminal fructose, sperm vitality and leucocytes (Endtz test) are useful adjuncts to semen analysis that provide information on specific clinical conditions. Though several computer-assisted sperm analysis (CASA) systems have been developed, conventional methods for semen analysis are still widely accepted in clinical practice. This review summarises the conventional techniques used in routine semen analysis and their diagnostic value in clinical andrology.

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.

The second mutation of SYCE1 gene associated with autosomal recessive nonobstructive azoospermia

PURPOSE

It is estimated that 40-50% of infertility among human couples is due to male infertility. Azoospermia is estimated to occur in 1% of all men and to be the cause of 10-20% of male infertility. Genetic defects, including single gene effects, maybe cause of azoospermia in 20-30% of affected males. Here, we aim to identify the genetic cause of azoospermia in a man who is also affected by hereditary spastic paraplegia.

METHODS

The proband was subjected to whole-exome sequencing, followed by a comprehensive in silico analysis to identify the azoospermia causative gene.

RESULTS

A novel splice site mutation c.375-2A > G in SYCE1 that is thought to be the cause of azoospermia was identified. This variant co-segregated with azoospermia status in the family that has three additional affected males.

CONCLUSION

SYCE1 gene encodes synaptonemal complex (SC) central element 1 protein which contributes to the formation of the synaptonemal complex during meiosis. Syce1 null male and female mice have been shown to be infertile. There have only been two reports on the effects of SYCE1 mutations in humans; it was shown as the cause of primary ovarian failure (POI) in one and as the cause of nonobstructive azoospermia (NOA) in another. We suggest that the mutation 375-2A > G, which affects the acceptor splice site within intron 6 of SYCE1, is the likely cause of azoospermia and subsequent infertility in the family studied. The finding constitutes the third report of SYCE1mutations that affect infertility in humans and further supports its contribution to this condition.

Male Infertility Diagnosis: Improvement of Genetic Analysis Performance by the Introduction of Pre-Diagnostic Genes in a Next-Generation Sequencing Custom-Made Panel

BACKGROUND

Infertility affects about 7% of the general male population. The underlying cause of male infertility is undefined in about 50% of cases (idiopathic infertility). The number of genes involved in human spermatogenesis is over two thousand. Therefore, it is essential to analyze a large number of genes that may be involved in male infertility. This study aimed to test idiopathic male infertile patients negative for a validated panel of "diagnostic" genes, for a wide panel of genes that we have defined as "pre-diagnostic."

METHODS

We developed a next-generation sequencing (NGS) gene panel including 65 pre-diagnostic genes that were used in 12 patients who were negative to a diagnostic genetic test for male infertility disorders, including primary spermatogenic failure and central hypogonadism, consisting of 110 genes.

RESULTS

After NGS sequencing, variants in pre-diagnostic genes were identified in 10/12 patients who were negative to a diagnostic test for primary spermatogenic failure (n = 9) or central hypogonadism (n = 1) due to mutations of single genes. Two pathogenic variants of DNAH5 and CFTR genes and three uncertain significance variants of DNAI1, DNAH11, and CCDC40 genes were found. Moreover, three variants with high impact were found in AMELY, CATSPER 2, and ADCY10 genes.

CONCLUSION

This study suggests that searching for pre-diagnostic genes may be of relevance to find the cause of infertility in patients with apparently idiopathic primary spermatogenic failure due to mutations of single genes and central hypogonadism.

Contribution of MTR A2756G polymorphism and MTRR A66G polymorphism to the risk of idiopathic male infertility

BACKGROUND

Methionine synthase reductase gene (MTRR A66G) polymorphism and methionine synthase gene (MTR A2756G) polymorphism have shown an association with idiopathic male infertility risk in several ethnic populations. However, their small sample sizes and inconsistent outcomes have prevented strong conclusions. We performed a meta-analysis with published studies to evaluate the associations of the 2 single nucleotide polymorphisms (SNPs) and idiopathic male infertility risk.

METHODS

A thorough literature search was performed up to Jun 21, 2019 with Medline, Embase, Web of Science, China National Knowledge Infrastructure (CNKI), China Biology Medical literature (CBM), China Science and Technology Journal Database (VIP), and Chinese literature (Wan Fang) databases. Odds ratio (OR) and 95% confidence interval (95% CI) were used to assess the strength of associations.

RESULTS

Seventeen studies including 3269 cases and 3192 controls met the inclusion criteria. Our meta-analysis showed that the MTR A2756G mutation may contribute to genetic susceptibility to the risk of idiopathic male infertility in Non-Asians, but not to Asian population, whereas the MTRR A66G polymorphism may be unrelated to idiopathic male infertility in both Non-Asian and Asian populations. In the stratified analysis by infertility type, the MTR A2756G polymorphism was a risk factor for both non-obstructive azoospermia (NOA) and oligoasthenoteratozoospermia (OAT) patients. However, the MTRR A66G polymorphism is associated with risk for OAT in Asian, but not in Non-Asian population.

CONCLUSION

This meta-analysis suggested that the MTR A2756G and MTRR A66G polymorphisms were risk factors for idiopathic male infertility. Studies with larger sample sizes and representative population-based cases and well-matched controls are needed to validate our results.

Sequence analysis of 37 candidate genes for male infertility: challenges in variant assessment and validating genes

BACKGROUND

The routine genetic analysis for diagnosing male infertility has not changed over the last twenty years, and currently available tests can only determine the etiology of 4% of unselected infertile patients. Thus, to create new diagnostic assays, we must better understand the molecular and genetic mechanisms of male infertility. Although next-generation sequencing allows for simultaneous analysis of hundreds of genes and the discovery of novel candidates related to male infertility, so far only a few gene candidates have enough sound evidence to support the gene-disease relationship.

OBJECTIVE

Since complementary studies are required to validate genes, we aimed to analyze the presence of potentially pathogenic rare variants in a set of candidate genes related to azoospermia in a hitherto understudied South American population.

SUBJECTS AND METHODS

We performed whole exome sequencing in a group of 16 patients with non-obstructive azoospermia from Ribeirão Preto, Brazil. Based on a recent systematic review of monogenic causes of male infertility, we selected a set of 37 genes related to azoospermia, Sertoli-Cell-Only histology, and spermatogenic arrest to analyze. The identified variants were confirmed by Sanger sequencing, and their functional consequence was predicted by in silico programs.

RESULTS

We identified potential pathogenic variants in seven genes in six patients. Two variants, c.671A>G (p.(Asn224Ser)) in DMRT1 and c.91C>T (p.(Arg31Cys)) in REC8, have already been described in association with azoospermia. We also found new variants in genes that already have moderate evidence of being linked to spermatogenic failure (TEX15, KLHL10), in genes with limited evidence (DNMT3B, TEX14) and in one novel promising candidate gene that has no evidence so far (SYCE1L).

DISCUSSION

Although this study included a small number of patients, the process of rationally selecting genes allowed us to detect rare potentially pathogenic variants, providing supporting evidence for validating candidate genes associated with azoospermia.

Integrated Analyses of Phenotype and Quantitative Proteome of CMTM4 Deficient Mice Reveal Its Association with Male Fertility

The chemokine-like factor (CKLF)-like MARVEL transmembrane domain-containing family (CMTM) is a gene family that has been implicated in male reproduction. CMTM4 is an evolutionarily conserved member that is highly expressed in the testis. However, its function in male fertility remains unknown. Here, we demonstrate that CMTM4 is associated with spermatogenesis and sperm quality. Using Western blotting and immunohistochemical analyses, we found CMTM4 expression to be decreased in poor-quality human spermatozoa, old human testes, and testicular biopsies with nonobstructive azoospermia. Using CRISPR-Cas9 technology, we knocked out the Cmtm4 gene in mice. These Cmtm4 knockout (KO) mice showed reduced testicular daily sperm production, lower epididymal sperm motility and increased proportion of abnormally backward-curved sperm heads and bent sperm midpieces. These mice also had an evident sub-fertile phenotype, characterized by low pregnancy rates on prolonged breeding with wild type female mice, reduced in vitro fertilization efficiency and a reduced percentage of acrosome reactions. We then performed quantitative proteomic analysis of the testes, where we identified 139 proteins to be downregulated in Cmtm4-KO mice, 100 (71.9%) of which were related to sperm motility and acrosome reaction. The same proteomic analysis was performed on sperm, where we identified 3588 proteins with 409 being differentially regulated in Cmtm4-KO mice. Our enrichment analysis showed that upregulated proteins were enriched with nucleosomal DNA binding functions and the downregulated proteins were enriched with actin binding functions. These findings elucidate the roles of CMTM4 in male fertility and demonstrates its potential as a promising molecular candidate for sperm quality assessment and the diagnosis or treatment of male infertility.

Upregulated lncRNA Gm2044 inhibits male germ cell development by acting as miR-202 host gene

Long non-coding RNAs (lncRNAs) have been found to participate in the regulation of human spermatogenic cell development. However, little is known about the abnormal expression of lncRNAs associated with spermatogenic failure and their molecular mechanisms. Using lncRNA microarray of testicular tissue for male infertility and bioinformatics methods, we identified the relatively conserved lncRNA Gm2044 which may play important roles in non-obstructive azoospermia. The UCSC Genome Browser showed that lncRNA Gm2044 is the miR-202 host gene. This study revealed that lncRNA Gm2044 and miR-202 were significantly increased in non-obstructive azoospermia of spermatogonial arrest. The mRNA and protein levels of Rbfox2, a known direct target gene of miR-202, were regulated by lncRNA Gm2044. Furthermore, the miR-202-Rbfox2 signalling pathway was shown to mediate the suppressive effects of lncRNA Gm2044 on the proliferation of human testicular embryonic carcinoma cells. Understanding of the molecular signalling pathways for lncRNA-regulated spermatogenesis will provide new clues into the pathogenesis and treatment of patients with male infertility.

Expression Analysis of the CRISP2, CATSPER1, PATE1 and SEMG1 in the Sperm of Men with Idiopathic Asthenozoospermia

BACKGROUND

The purpose of this study was to analyze the expression level of CRISP2, CATSPER1, PATE1 and SEMG1 genes in the sperm of men with asthenozoospermia (AZS). AZS is a cause of infertility in men in which the motility of the sperm is reduced. So far, a few genes have been associated with AZS; however, in most of the cases, its molecular etiology is unclear.

METHODS

A total of 35 subjects with idiopathic AZS and 35 fertile and healthy men as control were included. In study after total RNA extraction and cDNA synthesis, relative quantification was performed. B2M was used as the normalizer gene and fold change was calculated by 2^-ΔΔCt method. Mann-Whitney test was used to compare the expression levels between the case and control groups with significance level of p<0.05.

RESULTS

Our results showed that CRISP2 (p=0.03) and SEMG1 (p=0.03) were significantly down-and up-regulated in AZS men respectively compared to the controls. But CATSPER1 and PATE1 did not show significant changes.

CONCLUSION

Down-regulation of CRISP2 and up-regulation of SEMG1 were associated with AZS, which could be suggested as the potential candidate genes for the development of a diagnostic marker or potentially for more studies for treatment of AZS.

Association of single nucleotide polymorphism c.673C>A/p.Gln225Lys in SEPT12 gene with spermatogenesis failure in male idiopathic infertility in Northeast China

Male infertility is a complex multifactorial disease affecting approximately 10% of couples who want to have children. Some cases of infertility can be explained by genetic factors. Septins are members of the GTPase superfamily, which are involved in diverse biological processes including morphogenesis, compartmentalization, cytokinesis, and apoptosis. The septin 12 gene, SEPT12, is expressed exclusively in post-meiotic male germ cells and is considered as a critical gene for spermatogenesis. In this study, we evaluated 200 patients with non-obstructive azoospermia and detected mutations of 25 spermatogenesis-associated genes by targeted exome sequencing. We report a missense SEPT12 variant, c.673C>A/p.Gln225Lys, in an infertile man with non-obstructive azoospermia. The variation was located inside the GTPase domain and had a SIFT score of 0.02 (<0.50) and was considered to be 'probably damaging' by PolyPhen. This case may provide clues to help establish the relationship between SEPT12 gene alterations and some cases of idiopathic male infertility. The role of this variant should thus be investigated further.

Sex chromosomes-linked single-gene disorders involved in human infertility

Human infertility is a healthcare problem that has a worldwide impact. Genetic causes of human infertility include chromosomal aneuploidies and rearrangements and single-gene defects. The sex chromosomes (X and Y) are critical players in human fertility since they contain several genes essential for sex determination and reproductive traits for both men and women. This paper provides a review of the most common sex chromosomes-linked single-gene disorders involved in human infertility and their corresponding phenotypes. In addition to the Y-linked SRY gene, which mutations may cause XY gonadal dysgenesis and sex reversal, the deletions of genes present in AZF regions of the Y chromosome (DAZ, RBMY, DBY and USP9Y genes) are implicated in varying degrees of spermatogenic dysfunction. Furthermore, a list of X-linked genes (KAL1, NR0B1, AR, TEX11, FMR1, PGRMC1, BMP15 and POF1 and 2 regions genes (XPNPEP2, POF1B, DACH2, CHM and DIAPH2)) were reported to have critical roles in pubertal and reproductive deficiencies in humans, affecting only men, only women or both sexes. Mutations in these genes may be transmitted to the offspring by a dominant or a recessive inheritance.

Gene alterations and expression spectrum of SPATA33 in nonobstructive azoospermic Iranian men

Genetic abnormalities have been considered a significant cause of male infertility. Increased expression of SPATA33 during the first wave of spermatogenesis indicates its possible association with the meiotic process. The aim of the current study was to investigate the genetic variations in the SPATA33 gene and its expression in patients with nonobstructive azoospermia (NOA). A total of 100 Iranian NOA men with idiopathic infertility were taken as the case group. The control group comprised 100 fertile men who had at least one child. The presence of nucleotide variations was analyzed in both groups using the standard polymerase chain reaction (PCR) sequencing technique. For mRNA and protein expression studies, testicular biopsy specimens from 27 patients were subdivided into three groups: nine obstructive azoospermic patients with hypospermatogenesis as control; nine maturation arrest (MA) and nine Sertoli cell-only syndromes (SCOS) as case groups. The expression of SPATA33 at both mRNA and protein levels was compared among these three groups using the reverse transcription PCR technique, the realtime-PCR technique, and immunohistochemistry. Mutation analysis of the SPATA33 gene revealed five nucleotide changes among the population studied. All but one showed no significant differences between the groups. The genotype distributions of rs112536073A > T in the transcription factor binding site region with heterozygote and homozygote genotypes were significantly different ( p < 0.05) between the two groups. More heterozygotes of this polymorphism were observed in patients, whereas more homozygotes were detected in controls. Accordingly, the current study illustrated that alterations in SPATA33 gene, at least those found in this study, may not impair spermatogenesis in patients with NOA. Reduction of gene expression at the level of mRNA in patients with SCOS can be interpreted by the absence of germ cells in the testicular tissue of these patients.

Genetic mapping of a male factor subfertility locus on mouse chromosome 4

Male reproductive anomalies are widely distributed among mammals, and male factors are estimated to contribute to approximately 50% of cases of human infertility. The B10.M/Sgn (B10.M) mouse strain exhibits two adverse reproductive phenotypes: severe teratospermia and male subfertility. Although teratospermia is known to be heritable, the relationship between teratospermia and male subfertility has not been well characterized. The fertility of B10.M male mice is considerably lower (~ 30%) than that of standard laboratory mouse strains (~ 70%). To genetically analyze male subfertility, F2 males were produced by intercrossing the F1 progeny of female B10.M and male C3H/HeN mice. The fertility of each F2 male mouse was assessed based on the outcomes of matings with five females. Statistical analysis of correlations between the two reproductive phenotypes (teratospermia and subfertility) in F2 males (n = 177) revealed that teratospermia is not the cause of male subfertility. Quantitative trait loci (QTL) analysis of the male subfertility phenotype (n = 128) using GigaMUGA markers mapped one significant QTL peak to chromosome 4 at 62.9 centimorgans (cM) with a logarithm of odds score of 11.81 (P < 0.05). We named the QTL locus Mfsf1 (male factor subfertility 1). Further genetic analysis using recombinant males restricted the physical area to 1.53 megabasepairs (Mbp), encompassing 22 protein-coding genes. In addition, we found one significant QTL and one indicative QTL on chromosome 5 and 12, respectively, that interacted with the Mfsf1 locus. Our results demonstrate that genetic dissection of male subfertility in the B10.M strain is a useful model for characterizing the complex genetic mechanisms underlying reproduction and infertility.

Genetic and epigenetic variations associated with idiopathic recurrent pregnancy loss

Recurrent pregnancy loss (RPL) is a reproductive disorder defined as two or more successive and spontaneous pregnancy losses (before 20 weeks of gestation), which affects approximately 1-2% of couples. At present, the causes of RPL remain unknown in a considerable number of cases, leading to complications in treatment and high levels of stress in couples. Idiopathic recurrent pregnancy loss (iRPL) has become one of the more complicated reproductive problems worldwide due to the lack of information about its etiology, which limits the counseling and treatment of patients. For that reason, iRPL requires further study of novel factors to provide scientific information for determining clinical prevention and targeted strategies. The aim of this study is to describe the most recent and promising progress in the identification of potential genetic and epigenetic risk factors for iRPL, expanding the genetic etiology of the disease.

Human male infertility and its genetic causes

Background

Infertility affects about 15% of couples who wish to have children and half of these cases are associated with male factors. Genetic causes of azoospermia include chromosomal abnormalities, Y chromosome microdeletions, and specific mutations/deletions of several Y chromosome genes. Many researchers have analyzed genes in the AZF region on the Y chromosome; however, in 2003 the SYCP3 gene on chromosome 12 (12q23) was identified as causing azoospermia by meiotic arrest through a point mutation.

Methods

We mainly describe the SYCP3 and PLK4 genes that we have studied in our laboratory, and add comments on other genes associated with human male infertility.

Results

Up to now, The 17 genes causing male infertility by their mutation have been reported in human.

Conclusions

Infertility caused by nonobstructive azoospermia (NOA) is very important in the field of assisted reproductive technology. Even with the aid of chromosomal analysis, ultrasonography of the testis, and detailed endocrinology, only MD‐TESE can confirm the presence of immature spermatozoa in the testes. We strongly hope that these studies help clinics avoid ineffective MD‐TESE procedures.