Defining new genetic etiologies of male infertility: progress and future prospects

Genetic Insights into Azoospermia and Severe Oligozoospermia: Discovering Seven SNPs through GWAS and In Silico Analysis

Azoospermia and severe oligozoospermia represent the most extreme forms of male infertility. Despite their prevalence, the genetic foundations of these conditions are not well understood, with only a limited number of genetic factors identified so far. This study aimed to identify single-nucleotide polymorphisms (SNPs) linked to both azoospermia and severe oligozoospermia. We conducted a genome-wide association study (GWAS) involving 280 Greek males with normal semen parameters and 85 Greek males diagnosed with either azoospermia or severe oligozoospermia. Following rigorous quality control measures, our analysis identified seven SNPs associated with azoospermia/severe oligozoospermia. An in silico functional annotation was subsequently used to further investigate their role. These SNPs, found in regions not previously associated with male reproductive disorders, suggest novel genetic pathways that may contribute to these forms of infertility and pave the way for future studies. Additionally, this study sheds light on the significant role of noncoding RNAs in the pathogenesis of male infertility, with three of the identified SNPs situated in long intergenic non-coding RNAs (lincRNAs). Our findings highlight the intricate genetic landscape of azoospermia and severe oligozoospermia, underlining the necessity for more detailed studies to fully grasp the underlying mechanisms and their potential for informing diagnostic and therapeutic strategies.

The methylation status of GATA3 potentially predicts the outcomes of assisted reproductive technologies

Evaluation of methylation status of genes in sperm samples has been suggested for diagnosis of male infertility as well as prognosis of assisted reproductive technologies (ART) outcomes. In this study, we compared the methylation pattern of the GATA3 gene in infertile and fertile men as well as in infertile men with positive and negative ART outcome based on clinical pregnancy. Ejaculates were obtained from 42 infertile men with a negative ART outcome (group 1), 30 infertile men with a positive ART outcome (group 2), and 21 fertile men (control). Then, samples were subjected to genomic DNA isolation and subsequent TUNEL assay and methylation-specific PCR. The number of infertile men with at least one methylated allele of GATA3 was significantly higher compared to the control group (p = 0.022). Also, the number of patients with at least one methylated allele was significantly higher in group 1 compared to group 2 (p = 0.013). Moreover, the TUNEL assay revealed that the amount of sperm DNA fragmentation is higher in group 1 compared to group 2 (p = 0.008). The findings of our study demonstrated that the degree of GATA3 methylation can potentially differentiate between infertile and fertile men and more importantly can potentially predict the outcome of ART.

Epigenetics Role in Spermatozoa Function: Implications in Health and Evolution-An Overview

The unique properties of spermatozoa are established through the spermatogenesis and maturation processes concurrently with its epigenome. It is known that damage to epigenetic mechanisms can lead to reproductive problems. However, scientific reviews addressing the role of the spermatozoa epigenome during the reproductive process are scarce. Therefore, the aim of this review was to offer a detailed overview of current knowledge in the field of spermatozoa epigenetics and its consequent implications. A full search was performed through three databases by combining five keywords. Inclusion criteria were implemented to grant accessibility, relevance, and concretion. Besides, some articles were manually removed or added to obtain an adequate and complete collection of 485 scientific publications. This compilation was used to conduct the bibliometric analysis and the data review separately. Bibliometric results displayed that spermatozoa epigenetics is an active and growing research area. The bibliographic overview showed that sperm epigenome correlates with the development of its function, explaining the environmental influence on reproductive pathologies or abnormal inheritance. The main conclusions were that the normal performance of sperm is heavily reliant on its epigenetics and that this study area is burgeoning, with the potential ability to provide society with clinical innovations in a short-term period.

Analysis of sperm chromatin packaging and reproductive biomarker to evaluate the consequence of advanced male age

In this study, the semen parameters, sperm chromatin integrity, antioxidant enzyme levels, and reproductive hormone levels of subfertile male subjects from Pakistan were assessed in relation to their age. Data on the demographic characteristics of the 750 study participants, including their general health, body mass index (BMI), and reproductive status, were collected from subfertile men from Pakistan. Semen and blood were collected to determine standard semen parameters, sperm chromatin dispersion (Halosperm-SCD), sperm chromatin integrity using toluidine blue (TB) staining, sperm chromatin maturity using chromomycin A3 (CMA3+) staining, and reproductive hormone (FSH, LH, prolactin and testosterone levels). The patients were divided into three groups according to their age: Group 1 included male subjects aged 30 years or less (n = 90), Group 2 included male subjects between the ages of 31 and 40 years (n = 330), and Group 3 included male subjects over 40 years of age (n = 330). Conventional semen parameters, reactive oxygen species (ROS), superoxide dismutase (SOD), guaiacol peroxidase (GPX), catalase (CAT), and lipid peroxidation (MDA) did not statistically (p > 0.05) differ with increasing male age or between different age groups. When compared to younger men (<30 years), sperm SCD (23.2 ± 0.88%) was significantly (p = 0.01) lower as compared to male patients aged >40 years (26.6 ± 0.6%). The concentration of LH, FSH, and testosterone levels were comparable between the groups (p > 0.05), while a significant (p = 0.04) increase in sperm chromatin immaturity CMA3+ (30 ± 0.71%) was observed in the old age group (>40 years) compared to the <30-year group (26.6 ± 1.03%). A positive association was observed between advanced male age and sperm chromatin dispersion (SCD) (r = 0.124, p = 0.001) and decondensation (CMA3+) (r = 0.1, p = 0.009). Despite potential limitations, this study has been carried out with extensive information on the potential risk of male age on sperm integrity. The present study demonstrated the impact of male age on male reproductive health, as these patients had a higher percentage of sperm chromatin damage (SCD) in their semen. Sperm DNA damage assessment will help in the evaluation and diagnosis of the underlying cause of poor fertility and can help clinicians in selecting the right treatment options. Male age is one of the factors that have an impact on the decline in male fertility. As a result, it is preferable for patients receiving assisted reproductive technology to be younger.

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

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

Infertility in Men: Advances towards a Comprehensive and Integrative Strategy for Precision Theranostics

Male infertility is an increasing and serious medical concern, though the mechanism remains poorly understood. Impaired male reproductive function affects approximately half of infertile couples worldwide. Multiple factors related to the environment, genetics, age, and comorbidities have been associated with impaired sperm function. Present-day clinicians rely primarily on standard semen analysis to diagnose male reproductive potential and develop treatment strategies. To address sperm quality assessment bias and enhance analysis accuracy, the World Health Organization (WHO) has recommended standardized sperm testing; however, conventional diagnostic and therapeutic options for male infertility, including physical examination and semen standard analysis, remain ineffective in relieving the associated social burden. Instead, assisted reproductive techniques are becoming the primary therapeutic approach. In the post-genomic era, multiomics technologies that deeply interrogate the genome, transcriptome, proteome, and/or the epigenome, even at single-cell level, besides the breakthroughs in robotic surgery, stem cell therapy, and big data, offer promises towards solving semen quality deterioration and male factor infertility. This review highlights the complex etiology of male infertility, especially the roles of lifestyle and environmental factors, and discusses advanced technologies/methodologies used in characterizing its pathophysiology. A comprehensive combination of these innovative approaches in a global and multi-centric setting and fulfilling the suitable ethical consent could ensure optimal reproductive and developmental outcomes. These combinatorial approaches should allow for the development of diagnostic markers, molecular stratification classes, and personalized treatment strategies. Since lifestyle choices and environmental factors influence male fertility, their integration in any comprehensive approach is required for safe, proactive, cost-effective, and noninvasive precision male infertility theranostics that are affordable, accessible, and facilitate couples realizing their procreation dream.

The Impact of Luteinizing Hormone/Chorionic Gonadotropin Hormone Receptor Gene Polymorphism rs68073206 in Men with Non-obstructive Azoospermia: A Case-control Study

Background: The functional consequences of the luteinizing hormone/chorionic gonadotropin hormone receptor (LHCGR) gene single nucleotide polymorphism (rs68073206) on male infertility in patients with non-obstructive azoospermia (NOA) is not clear. Objective: To examine whether the presence of LHCGR gene; rs68073206 single nucleotide polymorphisms (SNPs) can be associated with incidence of non-obstructive azoospermia. Materials and methods: A case-control study comprised of a total of 70 unrelated Iraqi infertile men with non-obstructive azoospermia (zero sperm in semen) whose were on two groups: Group I that were diagnosed to have NOA but didn’t receive infertility treatment yet (33 patient with age of 31.58±1.059 year) and group II that were receiving injectable gonadotropin treatment (37 patient with age of 33.46±1.173 year). In addition to 34 age and BMI matched healthy fertile normozoospermic men (according to the parameters of WHO, 2010). The study population was genotyped by TaqMan assay for LHCGR gene single nucleotide polymorphism (rs68073206). The level of each hormone was estimated by immunoassay technique while the sperm analyses were conducted in accordance with the World Health Organization criteria. Results: The study revealed a statistically significant higher hormonal level of serum inhibin B in infertile group I patients with wild GG genotype (246.445±224.106 pg/ml), and the p-value is (0.0439) as compared to that hormone levels of GT and TT genotypes carriers that were (85.969±71.685 pg/ml) and (56.420±23.988 pg/ml) respectively. ). The genotyping variations of patients, whether carrying the homozygous GG, heterozygous GT or homozygous TT genotype, did not reveal a statistically significant difference in distribution as compared to control individuals. Conclusions: The LHCGR gene rs68073206 polymorphisms in our population having non-obstructive azoospermia can be suggested to have a modulating potential in variable gonadotropin sensitivity. The detected non-significant difference in genotypic prevalence can be attributable to the limited sample size.