Susceptibility to idiopathic azoospermia in Japanese men is linked to HLA class I antigen

Semen quality is affected by HLA class I alleles together with sexually transmitted diseases

BACKGROUND

The human leukocyte antigen (HLA) locus includes several genes with key roles in antigen presentation and immune response, some of them inclusively found to be associated with non-obstructive azoospermia. Still, HLA connections to other infertility phenotypes such as semen hyperviscosity (SHV), asthenozoospermia (AST), and oligozoospermia (OLI) have been often neglected.

OBJECTIVES

In this work, we aimed to evaluate the association of HLA class I and II genes with SHV, AST, and OLI phenotypes while exploring a possible role in an adaptive immune response to sexually transmitted diseases (STD).

MATERIALS AND METHODS

Whole-exome sequencing was performed in a Portuguese cohort of 71 infertility cases and 68 controls, followed by HLA typing using a specific software-HLA*PRG:LA tool. Molecular screenings of seven STD were carried out in a subset of 72 samples (30 cases and 42 controls).

RESULTS

Statistical tests uncovered three protective alleles: HLA-A*11:01, associated with all forms of male infertility (p = 0.0006); HLA-DQB1*03:02 with SHV and OLI (P_SHV   = 0.0303, P_OLI   = 0.0153); and HLA-A*29:02 with OLI (p = 0.0355), which was found to interfere in sperm number together with HPV (p = 0.0313). Five risk alleles were also identified: two linked with SHV (HLA-B*50:01, p = 0.0278; and HLA-C*06:02, p = 0.0461), another one with both SHV and OLI (HLA-DQA1*05:01, P_SHV   = 0.0444 and P_OLI =0.0265), and two with OLI (HLA-C*03:03, p = 0.0480; and HLA-DQB1*03:01, p = 0.0499). Here, HLA-C*03:03 carriers tend to be HPV infected.

CONCLUSIONS

The application of HLA*PRG:LA tool to the study of male infertility provided novel insights for an HLA correlation with semen quality, namely among SHV and OLI phenotypes. The discovery of an HLA-A*29:02/HPV crosstalk, together with former reports of HLA alleles conferring resistance-susceptibility to diverse human pathogens, raises the hypothesis of a mechanistic link between male infertility, HLA polymorphism, and host response to STD.

Fine mapping the MHC region identified rs4997052 as a new variant associated with nonobstructive azoospermia in Han Chinese males

OBJECTIVE

To investigate the association between genetic variants in the major histocompatibility complex (MHC) region and nonobstructive azoospermia (NOA) susceptibility.

DESIGN

MHC region fine-mapping analysis based on previous NOA genome-wide association study (GWAS) data.

SETTING

Medical university.

PATIENT(S)

Nine hundred and eighty-one men with NOA and 1,657 normal fertile male controls.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

The MHC region imputation assessed with SNP2HLA software, taking the specific Han-MHC database as a reference panel; statistical significance of the MHC variants calculated using logistic regression models; functional annotation based on online public databases; and phenotypic variances explained by specific groups of genetic variants estimated using the fixed effects model from individual associations.

RESULT(S)

Two independent risk loci, rs7194 (odds ratio [OR] 1.37) at MHC class II molecules and rs4997052 (OR 1.30) at MHC class I molecules, were identified. Functional annotation showed rs7194 may tag the effect of multiple amino acid residues and the expression of HLA-DQB1 and HLA-DRB1; while rs4997052 showed the effect of amino acid changes of HLA-B at position 116 as well as the expression of HLA-B and CCHCR1, which coexpressed with genes enriched in pathways of spermatogenesis and male gamete generation. The novel variant rs4997052 identified in our study can explain another approximately 0.66% of the phenotypic variances of NOA.

CONCLUSION(S)

We fine-mapped the MHC region and identified two loci that independently drove NOA susceptibility. These results provide a deeper understanding of the association mechanisms of MHC and NOA risk.

Association study of HLA-B alleles with idiopathic male infertility in Han population of China

PURPOSE

To investigate the distributions of HLA-B alleles and estimate their associations with idiopathic male infertility in Chinese Han population.

METHODS

Polymerase chain reaction-sequence-based typing (PCR-SBT) method was used for DNA typing at HLA-B locus in 109 patients with idiopathic male infertility and 152 healthy controls in male Han population of Shaanxi Province, situated in northwestern China.

RESULTS

In total, we detected 45 HLA-B alleles in idiopathic infertile patients, 48 HLA-B alleles in control subjects. However, no significant differences of these allelic frequencies were found between the infertile patients and the controls.

CONCLUSION

HLA-B gene was unlikely a major risk factor of idiopathic male infertility in this sample population. As different populations have different HLA polymorphisms, investigation of the relationship of other HLA genes and idiopathic male infertility with larger sample size, is warranted in the future.

Clinical analysis of patients with azoospermia factor deletions by microdissection testicular sperm extraction

Microdeletions of the azoospermia factor (AZF) locus on the Y chromosome have been implicated as a major genetic component of idiopathic male infertility, and the incidence of AZF deletions has been reported to be 15-20% in men with non-obstructive azoospermia (NOA). Numerous studies have described AZF deletion rates in patients with azoospermia; however, a clinical comparison of azoospermic patients with AZF deletion and those with no deletion has not been reported well. A new technique for testicular sperm extraction, microdissection testicular sperm extraction (TESE), has been used widely on NOA patients. Although testicular spermatozoa are reliably detected and retrieved from NOA patients by microdissection TESE, sperm retrieval rates for patients with AZF deletions are not well known. Therefore, characteristics of NOA patients with AZF deletion were investigated. Six of 60 patients (10%) who underwent microdissection TESE were found to have AZF deletions by genomic polymerase chain reaction. Testicular data, outcome of sperm retrieval and endocrinological profiles, were compared between patients with AZF deletions (n = 6) and those with no deletions (n = 54). Testicular size, varicocele rates and testicular histology were similar between the groups. Significant differences were not detected in the endocrinological profiles. Sperm retrieval rates were not significantly different between the groups. In conclusion, AZF deletions do not appear to confer specific characteristics to NOA patients.

Susceptibility locus for non-obstructive azoospermia is localized within the HLA-DR/DQ subregion: primary role of DQB1*0604

Non-obstructive azoospermia is a male infertility characterized by no or little sperm in semen as a result of a congenital dysfunction in spermatogenesis. Previous studies have reported a higher prevalence of particular human leukocyte antigen (HLA) antigens in non-obstructive azoospermia. As the expression of the RING3 gene located in the HLA class II region was predominant in the testis, mainly around spermatids and pachytene spermatocytes, it is tempting to speculate that RING3 is one of the strong candidate genes responsible for the pathogenesis of the disease. In this study, the genetic polymorphism in the RING3 gene was investigated by the direct sequencing technique. As a result, a total of 14 single nucleotide polymorphisms were identified. Among them, six were localized in the coding region but none of them was accompanied by an amino-acid substitution. No significant difference in the allelic distribution at these 14 polymorphic sites was observed between the patients and healthy controls, suggesting that the susceptible gene for non-obstructive azoospermia is not the RING3 gene. Then, in order to map the susceptibility locus for non-obstructive azoospermia precisely within the HLA region, 11 polymorphic microsatellite markers distributed from the SACM2L gene just outside the HLA class II region (187 kb telomeric of the DPB1 gene) to the OTF3 gene in the HLA class I region were subjected to association analysis in the patients. Statistical analysis of distribution in the allelic frequency at each microsatellite locus demonstrated that the pathogenic gene for non-obstructive azoospermia is located within the HLA-DR/DQ subregion. In fact, DRB1*1302 and DQB1*0604 were found to be strongly associated with non-obstructive azoospermia by polymerase chain reaction-based DNA typing. Further, haplotype analysis suggested that the DQB1*0604 allele may play a decisive role in the pathogenesis of non-obstructive azoospermia.

Susceptibility to vesicoureteral reflux in Japanese is linked to HLA-DR antigen

OBJECTIVES

To determine whether vesicoureteral reflux is associated with the human leukocyte antigen (HLA) genes.

METHODS

We evaluated 40 Japanese patients (27 males and 13 females) with reflux. HLA-DR low-resolution genotyping and high-resolution typing of HLA-DRB1 alleles were performed. The frequencies of the HLAs and alleles were calculated and compared with those previously reported in 493 healthy Japanese.

RESULTS

Low-resolution typing showed that the frequency of the HLA-DR11 antigen was significantly higher in the patients with reflux than in the control group. High-resolution typing revealed that the frequencies of HLA-DRB1*1101 and 1502 alleles were significantly higher in the patients with reflux than in the control group. In the patients with and without renal scarring, the frequencies of the HLA-DR11 antigens and HLA-DRB1*1101 alleles were significantly lower in those with renal scarring. In the patients with and without the chief complaint of urinary tract infection symptoms, the frequencies of HLA-DR13 antigens and HLA-DRB1*1302 alleles were significantly lower in those with that chief complaint.

CONCLUSIONS

The susceptibility to reflux is, in part, controlled by HLA genes themselves or an unknown gene or genes, the locus for which is located close to the DRB1 gene. The lack of a HLA-DRB1*1101 allele and DRB1*1302 allele in patients with reflux might be connected with renal scarring and urinary tract infection, respectively.