Association of single nucleotide polymorphisms in the USF1, GTF2A1L and OR2W3 genes with non-obstructive azoospermia in the Chinese population

Male Infertility in Humans: An Update on Non-obstructive Azoospermia (NOA) and Obstructive Azoospermia (OA)

Non-obstructive azoospermia (NOA) and obstructive azoospermia (OA) are two common causes of infertility that affect a considerable number of men. However, few studies were performed to understand the molecular etiology of these disorders. Studies based on bioinformatics and genetic analyses in recent years, however, have yielded insightful information and have identified a number of genes that are involved in these disorders. In this review, we briefly summarize and evaluate these findings. We also discuss findings based on epigenetic modifications of sperm DNAs that affect a number of genes pertinent to NOA and OA. The information summarized in this Chapter should be helpful to investigators in future functional studies of NOA and OA.

Genetic Landscape of Nonobstructive Azoospermia and New Perspectives for the Clinic

Nonobstructive azoospermia (NOA) represents the most severe expression of male infertility, involving around 1% of the male population and 10% of infertile men. This condition is characterised by the inability of the testis to produce sperm cells, and it is considered to have an important genetic component. During the last two decades, different genetic anomalies, including microdeletions of the Y chromosome, karyotype defects, and missense mutations in genes involved in the reproductive function, have been described as the primary cause of NOA in many infertile men. However, these alterations only explain around 25% of azoospermic cases, with the remaining patients showing an idiopathic origin. Recent studies clearly suggest that the so-called idiopathic NOA has a complex aetiology with a polygenic inheritance, which may alter the spermatogenic process. Although we are far from a complete understanding of the molecular mechanisms underlying NOA, the use of the new technologies for genetic analysis has enabled a considerable increase in knowledge during the last years. In this review, we will provide a comprehensive and updated overview of the genetic basis of NOA, with a special focus on the possible application of the recent insights in clinical practice.

Susceptibility to male infertility: replication study in Japanese men looking for an association with four GWAS-derived loci identified in European men

PURPOSE

A previous genome-wide association study in European men identified four single nucleotide polymorphism (SNP) loci associated with male infertility. Our aim was to replicate, if possible, the association of these SNPs with Japanese male infertility.

METHODS

We genotyped four SNPs (rs5911500, rs10246939, rs2059807, and rs11204546) in 517 Japanese patients with male infertility and 369 fertile controls using SNP-specific real-time polymerase chain reaction TaqMan assays. Subsequently, we divided patients with male infertility into azoospermia (n = 417) and oligospermia subgroups (n = 70).

RESULTS

The four SNPs previously identified in European men showed no significant association with collective male infertility in our Japanese cohort. However, allele frequency analysis did indicate a significantly higher frequency of the rs11204546 C allele of the OR2W3 gene in the oligospermia subset of infertility patients compared with controls (p = 0.0037; odds ratio = 1.74; 95 % confidence interval, 1.21-2.53).

CONCLUSIONS

Although this study was somewhat limited by overall sample size, the OR2W3 gene polymorphism rs11204546 was significantly associated with oligospermia in Japanese men, suggesting that OR2W3 might be involved in genetic susceptibility to Japanese male infertility as well as in European males.