Associations between male infertility and ancestry in South Americans: a case control study

Y-chromosome haplogroups and Azoospermia Factor (AZF) analysis in Tunisian infertile male

The aim of the present study was to clarify the implication of Y chromosome genetic variations and haplogroups in Tunisian infertile men. A total of 27 Y-chromosomal binary markers partial microdeletions (gr/gr, b1/b3 and b2/b3) and copy number variation of DAZ and CDY genes in the AZFc region were analysed in 131 Tunisian infertile men with spermatogenic failure and severe reduced sperm concentrations and in 85 normospermic men as controls. Eleven different haplogroups in the overall population study (E3b2; J1J*, E1, E3b*, F, G, K, P/Q, R*, R1* and R1a1) were found. Interestingly, the J1J* haplogroup was significantly more frequent in azoo/oligospermic patients than in normospermic men (35.1% and 22.3%, respectively (p value = 0.04)). Results showed also that patients without DAZ/CDY1 copies loss and without partial microdeletions belonged to the R1 haplogroup. The relative high frequencies of two haplogroups, E3b2 (35.1%) and J (30%) was confirmed in Tunisia. We reported in the present study and for the first time, that J1J* haplogroup may confer a risk factor for infertility in the Tunisian population and we suggested that R1 haplogroup may ensure certain stability to Y-chromosome in Tunisian men.

Insights into the Y chromosome human diversity in Uruguay

BACKGROUND

With regard to the origin of its population and microevolutionary processes, Uruguay exhibits distinctive features that distinguish it from other countries in Latin America, while at the same time sharing several similarities. In this article, we will focus on the variability of paternal genetic lineages in two geographical regions with different histories that can be considered as examples of distinct populations for the continent. In general terms, the genetic diversity is a result of different demographic processes related to the American conquest and colonisation. These resulted in distinct ancestral components which vary geographical and depend on the distribution by sex within these components. In Uruguay, native maternal haplogroups are significantly more frequent in the North. Although there are several studies about the geneticvariability of Uruguay, little is known about male genetic lineages.

AIMS

The aim of this work is to present an updated study of the male genetic variability of the Uruguayan population.

METHODS

We analyzed 13 biallelic markers and 27 STRs located in the male-specific region of the Y chromosome for 157 males: 98 from the capital, Montevideo, and 59 from Tacuarembó.

RESULTS

Almost all haplogroups found in both locations are European (99% and 93.2% respectively). One Sub-Saharan African haplogroup was found in Montevideo (1%) and 2 in Tacuarembó (3%), while Native haplogroups were found only in Tacuarembó, evidencing a strong sex-biased admixture. By crossing genetic and genealogical information we could relate European haplogroups with different waves and times of migrations.

DISCUSSION

Network analysis indicated a very diverse male population, suggesting that European migrants came from heterogeneous geographic locations and in different waves. Tacuarembó has closer population affinities with Iberian populations while Montevideo is more diverse. Male population expansion expansion, can be explained by the large number of migrants that arrived during the XIX century and the first half of the XX century.

CONCLUSIONS

The Uruguayan male gene pool is the result of several migration waves with diverse origins, with strong sex-biased admixture that can be explained by the European migration, the violence against the indigenous males, and the segregation of the Africansadmixture that can be explained due to European migration, violence against Natives, and segregation against African males.admixture that can be explained due to European migration, violence against Natives, and segregation against African males.admixture that can be explained due to European migration, violence against Natives, and segregation against African males.admixture that can be explained due to European migration, violence against Natives, and segregation of hte Africans.

Molecular genetic analysis of 1,980 cases of male infertility

The present study aimed to investigate the occurrence of chromosomal karyotype abnormalities and azoospermia factor (AZF) microdeletion on the long arm of the Y chromosome (Yq) in infertile men, and to determine their association with infertility to ultimately improve clinical outcomes in these patients. A total of 1,980 azoospermic and oligospermic men from the outpatient department of the Fujian Maternity and Child Health Hospital (Fuzhou, China) were recruited between January 2016 and December 2019. Peripheral blood was used for karyotype analysis; AZF microdeletion analysis of the Yq was performed using capillary electrophoresis. Among the 1,980 patients, 178 had chromosomal abnormalities (9.0%; 178/1,980), of whom 98 had an abnormal number of chromosomes. Among the abnormal karyotypes, the most common was 47, XXY (80/178; 44.9%). AZF microdeletion on the Yq occurred at a rate of 10.66% (211/1,980); the most common type was the AZFb/c deletion (sY1192; 140/211; 66.4%). The present findings showed that karyotype abnormalities and AZF gene microdeletion are important drivers of male infertility. Specifically, men with Yqh- and del(Y)(q11) had a higher risk of AZF microdeletion. These results suggested that patient treatment could be personalized based on routine molecular genetic analysis, which could further alleviate the economic and emotional burden of undergoing redundant or ineffective treatments.

Mitochondria: their role in spermatozoa and in male infertility

BACKGROUND

The best-known role of spermatozoa is to fertilize the oocyte and to transmit the paternal genome to offspring. These highly specialized cells have a unique structure consisting of all the elements absolutely necessary to each stage of fertilization and to embryonic development. Mature spermatozoa are made up of a head with the nucleus, a neck, and a flagellum that allows motility and that contains a midpiece with a mitochondrial helix. Mitochondria are central to cellular energy production but they also have various other functions. Although mitochondria are recognized as essential to spermatozoa, their exact pathophysiological role and their functioning are complex. Available literature relative to mitochondria in spermatozoa is dense and contradictory in some cases. Furthermore, mitochondria are only indirectly involved in cytoplasmic heredity as their DNA, the paternal mitochondrial DNA, is not transmitted to descendants.

OBJECTIVE AND RATIONAL

This review aims to summarize available literature on mitochondria in spermatozoa, and, in particular, that with respect to humans, with the perspective of better understanding the anomalies that could be implicated in male infertility.

SEARCH METHODS

PubMed was used to search the MEDLINE database for peer-reviewed original articles and reviews pertaining to human spermatozoa and mitochondria. Searches were performed using keywords belonging to three groups: 'mitochondria' or 'mitochondrial DNA', 'spermatozoa' or 'sperm' and 'reactive oxygen species' or 'calcium' or 'apoptosis' or signaling pathways'. These keywords were combined with other relevant search phrases. References from these articles were used to obtain additional articles.

OUTCOMES

Mitochondria are central to the metabolism of spermatozoa and they are implicated in energy production, redox equilibrium and calcium regulation, as well as apoptotic pathways, all of which are necessary for flagellar motility, capacitation, acrosome reaction and gametic fusion. In numerous cases, alterations in one of the aforementioned functions could be linked to a decline in sperm quality and/or infertility. The link between the mitochondrial genome and the quality of spermatozoa appears to be more complex. Although the quantity of mtDNA, and the existence of large-scale deletions therein, are inversely correlated to sperm quality, the effects of mutations seem to be heterogeneous and particularly related to their pathogenicity.

WIDER IMPLICATIONS

The importance of the role of mitochondria in reproduction, and particularly in gamete quality, has recently emerged following numerous publications. Better understanding of male infertility is of great interest in the current context where a significant decline in sperm quality has been observed.

Association of MSY haplotype background with nonobstructive azoospermia is AZF-dependent: A case-control study

Identifying causal genes of spermatogenic failure on the male-specific region of Y chromosome (MSY) has been a challenging process. Due to the nonrecombining nature of MSY, haplotype-based approaches have recently been shown to be promising in identifying associated MSY haplogroups. We conducted an MSY analysis of nonobstructive azoospermia (NOA) patients in a case-control setting (N = 278 and 105 respectively) to identify modal haplogroups strongly associated with NOA. Patients with AZF deletions (AZF+) and no AZF deletions (AZF-) were compared with the control group. Given the larger sample set of AZF- NOA patients, we further investigated the association based on histopathological severity, namely Sertoli cell-only syndrome and maturation arrest subtypes. We observed no significant enrichment of MSY haplogroups in AZF- azoospermic patients (or its subtypes). However, we observed a strongly significant association between haplogroup J2a* and AZF+ patients (FDR-corrected p = .0056; OR = 7.02, 95%CI 1.89 to 39.20), a haplogroup which also showed significant enrichment for AZFa/b deletions (p = 4x10^-4 ). We conclude that unlike AZF+ patients, AZF- NOA are less likely to have an MSY causative factor with large effect size, thus indicating that the aetiology of AZF- NOA, and to some extent AZFc NOA, is more likely to be based on non-MSY factors.

Partial-AZFc deletions in Chilean men with primary spermatogenic impairment: gene dosage and Y-chromosome haplogroups

PURPOSE

To investigate the association of partial-AZFc deletions in Chilean men with primary spermatogenic failure and their testicular histopathological phenotypes, analyzing the contribution of DAZ dosage, CDY1 copies, and Y-chromosome haplogroups.

SUBJECTS AND METHODS

We studied 479 Chilean men: 334 infertile patients with histological examination (233 cases with spermatogenic defects and 101 normal spermatogenesis, obstructive controls, OC), and 145 normozoospermic controls (NC). AZFc subdeletions were detected by single-tagged sequences and single nucleotide variants analysis. DAZ-copy number was quantified by real-time qPCR. Y-chromosome haplogroups (Y-hg) were hierarchically genotyped through 16 biallelic-markers.

RESULTS

The prevalence of AZFc-partial deletions was increased in cases (6%) compared with NC (1.4%) (P = 0.035). There was no difference between 143 Sertoli-cell only syndrome, 35 maturation arrest, or 35 mix atrophy patients and controls. However, gr/gr deletions were more frequent in 16 subjects with hypospermatogenesis compared with NC (P = 0.003) and OC (P = 0.013). Y-hg R was the most prevalent (~ 50%), but decreased among gr/gr deletions (21%, P = 0.03). The prevalence of Y-hg M increased in cases versus controls, both in total and non-deleted men (3.9 and 3.7% versus 0.4%, P = 0.009 and P = 0.016, respectively). Among gr/gr deletions, Y-hg H increased compared with non-deleted men (14.3% versus 0.4%, P = 0.0047).

CONCLUSION

Partial-AZFc deletions in a Chilean admixed population are associated with secretory azo/oligozoospermia and might have a role in the development of hypospermatogenesis. Low represented haplogroups, Y-hg M and Y-hg H, show an association with the occurrence of spermatogenic failure and gr/gr deletions respectively; however, additional studies are required.

Mitochondria, spermatogenesis, and male infertility - An update

The incorporation of mitochondria in the eukaryotic cell is one of the most enigmatic events in the course of evolution. This important organelle was thought to be only the powerhouse of the cell, but was later learnt to perform many other indispensable functions in the cell. Two major contributions of mitochondria in spermatogenesis concern energy production and apoptosis. Apart from this, mitochondria also participate in a number of other processes affecting spermatogenesis and fertility. Mitochondria in sperm are arranged in the periphery of the tail microtubules to serve to energy demand for motility. Apart from this, the role of mitochondria in germ cell proliferation, mitotic regulation, and the elimination of germ cells by apoptosis are now well recognized. Eventually, mutations in the mitochondrial genome have been reported in male infertility, particularly in sluggish sperm (asthenozoospermia); however, heteroplasmy in the mtDNA and a complex interplay between the nucleus and mitochondria affect their penetrance. In this article, we have provided an update on the role of mitochondria in various events of spermatogenesis and male fertility and on the correlation of mitochondrial DNA mutations with male infertility.

Association between polymorphisms in the XRCC1 gene and male infertility risk: A meta-analysis

BACKGROUND

X-ray repair cross-complementing group 1 (XRCC1) single nucleotide polymorphisms (SNPs) might correlate with male infertility susceptibility. This association has been described; however, the findings remain inconsistent. Consequently, this meta-analysis was conducted to characterize the relationship between XRCC1 SNPs and male infertility susceptibility.

METHODS/MAIN RESULTS

Studies were systematically searched in databases to evaluate the association between SNPs of XRCC1 and infertility in males. The effect measures chosen were the 95% confidence intervals (95% CIs) and odds ratios (ORs). A total of 7 studies, including 6 case-controlled studies on XRCC1 Arg399Gln and 3 case-controlled studies on XRCC1 Arg194Trp, were included. Ultimately, the results of this analysis revealed that XRCC1 Arg399Gln SNPs were significantly associated with infertility in males in homozygote comparisons (GG vs GA+AA: OR = 0.614, 95% CI: 0.40-0.937, P = .024). This meta-analysis did not demonstrate a relationship between XRCC1 Arg194Trp and male infertility risk.

CONCLUSIONS

Our study indicated that XRCC1 Arg399Gln polymorphism was associated with a significantly decreased male infertility risk, but not XRCC1 Arg194Trp.