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The number of couples that meet the definition of infertility at reproductive ages is increasing worldwide. One of the most known conditions of infertility in males is azoospermia, defined as complete absence of spermatozoa in the semen. Azoospermia manifests in two forms, namely obstructive and non-obstructive azoospermia. Although the presence of antisperm antibody (ASA) has been reported in 88% of the patients with obstructive azoospermia (OA), interestingly, there is no data regarding ASA targets in OA individuals.
Testicular sperm retrieval techniques associated with intracytoplasmic sperm injection have changed the field of male infertility treatment and given many azoospermic men the chance to become biological fathers. Despite the current use of testicular sperm extraction, reliable clinical and laboratory prognostic factors of sperm recovery are still absent. The objective of this article was to review the prognostic factors and clinical use of sperm retrieval for men with non-obstructive azoospermia. The PubMed database was searched for the Medical Subject Headings (MeSH) terms azoospermia, sperm retrieval, and prognosis. Papers on obstructive azoospermia were excluded. The authors selected articles that reported successful sperm retrieval techniques involving clinical, laboratory, or parenchyma processing methods. The selected papers were reviewed, and the prognostic factors were discussed. No reliable positive prognostic factors guarantee sperm recovery for patients with non-obstructive azoospermia. The only negative prognostic factor is the presence of AZFa and AZFb microdeletions.
Meiotic homologous recombination (HR) plays an essential role in gametogenesis. In most eukaryotes, meiotic HR is mediated by two recombinase systems: ubiquitous RAD51 and meiosis-specific DMC1. In the RAD51-mediated HR system, RAD51 and five RAD51 paralogues are essential for normal RAD51 function, but the role of RAD51 in human meiosis is unclear. The knockout of Rad51 or any Rad51 paralogue in mice exhibits embryonic lethality. We investigated a family with meiotic arrest, azoospermia and infertility but without other abnormalities.
Non-obstructive azoospermia is a severe infertility factor. Currently, the etiology of this condition remains elusive with several possible molecular pathway disruptions identified in the post-meiotic spermatozoa. In the presented study, in order to identify all possible candidate genes associated with azoospermia and to map their relationship, we present the first protein-protein interaction network related to azoospermia and analyze the complex effects of the related genes systematically. Using Online Mendelian Inheritance in Man, the Human Protein Reference Database and Cytoscape, we created a novel network consisting of 209 protein nodes and 737 interactions. Mathematical analysis identified three proteins, ar, dazap2, and esr1, as hub nodes and a bottleneck protein within the network. We also identified new candidate genes, CREBBP and BCAR1, which may play a role in azoospermia. The gene ontology analysis suggests a genetic link between azoospermia and liver disease. The KEGG analysis also showed 45 statistically important pathways with 31 proteins associated with colorectal, pancreatic, chronic myeloid leukemia and prostate cancer. Two new genes and associated diseases are promising for further experimental validation.
While most men with non-obstructive azoospermia (NOA) are not amenable to medical treatment, some men can be treated effectively with hormonal therapy, prior to considering surgery. In some cases, hormonal therapy alone can treat NOA, without the need for surgery. In other cases, correction of a potential hormonal imbalance can enhance the chances of success of surgical sperm retrieval (SSR), with either conventional or microdissection testicular sperm extraction. Abnormal testicular function and low androgen levels can result from a primary dysfunction, a medical or surgical condition, or from an exogenous factor, and should be managed prior to more invasive interventions. Even men with normal androgen levels may benefit from hormonal therapy before sperm retrieval. Moreover, SSR may cause testicular injury and aggravate the pre-existing situation. If surgical extraction of sperm fails, it leaves the patients with less satisfactory options, like donor sperm or adoption. Therefore, it is the role of the infertility specialist to be vigilant and identify reversible causes of NOA, such as hormonal imbalance, prior to considering surgery. In the present paper we will systematically review the literature and highlight the available conventional medical regimens, as well as experimental ones. Abbreviations: ART: assisted reproductive technology; CAH: congenital adrenal hyperplasia; EAU: European Association of Urology; hCG: human chorionic gonadotrophin; HH: hypogonadotrophic hypogonadism; hMG: human menopausal gonadotrophin; IUI: intrauterine insemination; micro-TESE: microdissection testicular sperm extraction; NOA: non-obstructive azoospermia; OR: odds ratio; SCO: Sertoli-cell only; SERM: selective oestrogen receptor modulator; SRR: sperm retrieval rate; SSC: spermatogonia stem cell; TART: testicular adrenal rest tumour; WMD: weighted mean difference.
The aim of the present study was stereological evaluation of testes of azoospermic animal model using busulfan in rat. Three groups of male adult rats were used in this study. The first group was injected by single dose of busulfan (10 mg kg(-1)) and their testes were removed on day 35 post injection. The second group received double doses of busulfan with 21 days interval and their testes were removed on day 35 after the second injection. The testes of the third group were removed without busulfan therapy. In 10 circular transverse sections of tubules stained with hematoxylin-eosin, stereological parameters were measured. The testes were rated for its spermatogenic potential on a modified spermatogenic scale of 0 to 6. Cellular (germinal epithelium) diameter and area of the seminiferous tubules, total diameter and cross sectional area of the tubules of the seminiferous tubules in rats that received double doses of busulfan were less than the rats in single dose of busulfan and control groups (p < 0.05). Spermatogenesis index of seminiferous tubules in rats receiving two doses of busulfan was less than the rats received one dose of busulfan (p < 0.001) and the index of both treatment groups were less than the control group (p < 0.001). In conclusion, two doses of busulfan injection with 21 days interval produced an appropriate experimental model of induced azoospermia with comparable stereological indices of seminiferous tubules in rat.
Objective: To review the available literature and identify factors associated with successful outcomes after varicocele repair (VR) in the setting of non-obstructive azoospermia (NOA). Methods: The PubMed and EMBASE databases were searched for relevant articles. Primary outcomes were return of spontaneous spermatogenesis, sperm retrieval rates (SRRs), and unassisted and assisted pregnancy rates. Histopathological subtypes, when available, were used for subgroup analysis. Results: A total of 16 articles were finally included. The average sample size was 43 and average duration of follow-up was 10.5 months. The average rate of primary spermatogenesis after VR was 27.3%. The average SRR, across five studies in men with NOA undergoing microscopic testicular sperm extraction status after varicocelectomy, was 48.9% vs 32.1% for the untreated cohort groups, and the average spontaneous pregnancy rate was 5.24%. Histopathology subtype was a significant contributing factor when analysed. Conclusion: Varicocele repair should be considered in men with NOA, as it may allow some patients to avoid assisted reproductive technologies and improves success rates when utilised.
Azoospermia factors, located in the long arm of the Y chromosome, are critical for spermatogenesis, the microdeletions of AZF are considered to be associated with male infertility. In addition to complete deletion, several AZFc partial deletions were also detected in infertile men with wide phenotypic heterogeneity. In this study, we investigated the relevance of Y chromosome deletions, Y-linked CNVs and variable phenotypes in infertile men. To clarify the relationship between phenotypic heterogeneity and Y chromosome deletion in male infertility, we performed chromosomal microarray analysis (CMA) capable of analyzing thousands of loci simultaneously to investigate Y-linked copy number variations (CNVs). Firstly, we reviewed the results of Y chromosome screening in 554 infertile patients and then compared the results of CMA to routine Y chromosome screening in 29 patients with Y chromosomal microdeletions. Then, the Y-linked CNVs associated with oligoasthenospermia were identified according to ACMG standards and guidelines. The results indicated that the prevalence of Yq microdeletions was 5.23% (29/554), with 93% (27/29) of the deletions in the AZFc region among 554 infertile men recruited in this study. The results of CMA and multiplex-PCR-based AZFc deletion analysis were generally concordant, but CMA provided more details about location, size and OMIM genes involved in deletion fragments of the AZF region. Of 29 clinically infertile phenotype-related CNVs detected by CMA, nine were pathogenic and the remaining 20 CNVs were OVUS. Except for a 15.69 Mb loss CNV in AZFa + b + c and an 8.25 Mb loss CNV in AZFb + c, others were located in the AZFc region. Based on a combination of the clinical symptoms and loss CNVs, we concluded that the CNV size and the involvement of spermatogenesis critical genes are two important factors that determine the relevance of a CNV in the AZFc region to the presence or absence of a clinically infertile phenotype.
Although chromosome rearrangements are responsible for spermatogenesis failure, their impact depends greatly on the chromosomes involved. At present, karyotyping and Y chromosome microdeletion screening are the first-line genetic tests for patients with non-obstructive azoospermia. Although it is generally acknowledged that X or Y chromosome rearrangements lead to meiotic arrest and thus rule out any chance of sperm retrieval after a testicular biopsy, we currently lack markers for the likelihood of testicular sperm extraction (TESE) in patients with other chromosome rearrangements.
Secretory azoospermia is a severe form of male infertility caused by unknown factors. DAX-1 is predominantly expressed in mammalian reproductive tissues and plays an important role in spermatogenesis because Dax-1 knockout male mice show spermatogenesis defects. To examine whether DAX-1 is involved in the pathogenesis of secretory azoospermia in humans, we sequenced all of the exons of DAX-1 in 776 patients diagnosed with secretory azoospermia and 709 proven fertile men. A number of coding mutations unique to the patient group, including two synonymous mutations and six missense mutations, were identified. Of the missense mutations, our functional assay demonstrated that the V385L mutation caused the reduced functioning of DAX-1. This novel mutation (p. V385L) of DAX-1 is the first to be identified in association with secretory azoospermia, thereby highlighting the important role of DAX-1 in spermatogenesis.
There are many unknown genetic factors that lead to infertility in nonobstructive azoospermia men. Here, we performed whole-exome sequencing in blood samples obtained from 40 azoospermia patients with meiotic arrest and found a novel c.151_154del (p.D51fs) frame-shift mutation in exon 3 of the testis expressed 11 (TEX11) gene in one patient. Sanger sequencing analysis of the patient and 288 fertile men was performed to validate the mutation. Immunohistochemical analysis showed TEX11 expression in late-pachytene spermatocytes and in round spermatids in fertile human testes. In contrast, testes of the patient with TEX11 mutation underwent meiotic arrest and lacked TEX11 expression. Western blotting of human embryonic kidney (HEK293) cells transfected with a vector for the p.D51fs TEX11 variant detected no TEX11 expression. In conclusion, we identified a novel frame-shift mutation in the TEX11 gene in an azoospermia patient, emphasizing that this gene should be included in genetic screening panels for the clinical evaluation of azoospermia patients.
Genetic factors are candidates for about 30% of male infertility with sperm production-related abnormalities. Y chromosome microdeletions are responsible for around 10% of male infertility. These microdeletions generally occur in azoospermia factor on the Yq. That is often associated with the quantitative reduction of sperm.
Tudor domain-containing proteins (TDRDs) play a critical role in piRNA biogenesis and germ cell development. piRNAs, small regulatory RNAs, act by silencing of transposons during germline development and it has recently been shown in animal model studies that defects in TDRD genes can lead to sterility in males.
The purpose of the study was to investigate whether micro-TESE can improve sperm retrieval rate (SRR) compared to conventional single TESE biopsy on the same testicle or to contralateral multiple TESE, by employing a novel stepwise micro-TESE approach in a population of poor prognosis patients with non-obstructive azoospermia (NOA).
A number of culture-dependent and -independent studies have reported that the number and significance of bacterial species in semen may have been underestimated. The aim of the present study was to profile the seminal microbiome in patients with obstructive or non-obstructive azoospermia. A high-throughput sequencing method was adopted to sequence genomic DNA extracted from the semen of healthy people (C group), patients with obstructive azoospermia (OA group) and patients with non-obstructive azoospermia (NOA group). The results revealed that Firmicutes, Proteobacteria, Bacteroidetes and Actinobacteria species comprised the majority of bacteria in the C (98.14%), OA (98.26%) and NOA (90.96%) groups. Patients in the OA and NOA groups exhibited an increase in Bacteroidetes and Firmicutes, whereas the number of Proteobacteria and Actinobacteria were decreased compared with the C group. A total of 398 common operational taxonomic units were identified, of which 27 belonged to the genus Lactobacillus. Furthermore, Phylogenetic Investigation of Communities by Reconstruction of Unobserved States analysis indicated that the pathogenic species and reduced biodiversity in the semen of patients with azoospermia may result in an increased risk of metabolic, infectious and immune diseases. In the present study, the seminal microbiome of patients with obstructive or non-obstructive azoospermia was explored, which may be useful for developing novel treatments against azoospermia as well as for its diagnosis.
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