Changes in environmental exposures over decades may influence the genetic architecture of severe spermatogenic failure.

STUDY QUESTION: Do the genetic determinants of idiopathic severe spermatogenic failure (SPGF) differ between generations? SUMMARY ANSWER: Our data support that the genetic component of idiopathic SPGF is impacted by dynamic changes in environmental exposures over decades. WHAT IS KNOWN ALREADY: The idiopathic form of SPGF has a multifactorial etiology wherein an interaction between genetic, epigenetic, and environmental factors leads to the disease onset and progression. At the genetic level, genome-wide association studies (GWASs) allow the analysis of millions of genetic variants across the genome in a hypothesis-free manner, as a valuable tool for identifying susceptibility risk loci. However, little is known about the specific role of non-genetic factors and their influence on the genetic determinants in this type of conditions. STUDY DESIGN, SIZE, DURATION: Case-control genetic association analyses were performed including a total of 912 SPGF cases and 1360 unaffected controls. PARTICIPANTS/MATERIALS, SETTING, METHODS: All participants had European ancestry (Iberian and German). SPGF cases were diagnosed during the last decade either with idiopathic non-obstructive azoospermia (n = 547) or with idiopathic non-obstructive oligozoospermia (n = 365). Case-control genetic association analyses were performed by logistic regression models considering the generation as a covariate and by in silico functional characterization of the susceptibility genomic regions. MAIN RESULTS AND THE ROLE OF CHANCE: This analysis revealed 13 novel genetic association signals with SPGF, with eight of them being independent. The observed associations were mostly explained by the interaction between each lead variant and the age-group. Additionally, we established links between these loci and diverse non-genetic factors, such as toxic or dietary habits, respiratory disorders, and autoimmune diseases, which might potentially influence the genetic architecture of idiopathic SPGF. LARGE SCALE DATA: GWAS data are available from the authors upon reasonable request. LIMITATIONS, REASONS FOR CAUTION: Additional independent studies involving large cohorts in ethnically diverse populations are warranted to confirm our findings. WIDER IMPLICATIONS OF THE FINDINGS: Overall, this study proposes an innovative strategy to achieve a more precise understanding of conditions such as SPGF by considering the interactions between a variable exposome through different generations and genetic predisposition to complex diseases. STUDY FUNDING/COMPETING INTEREST(S): This work was supported by the "Plan Andaluz de Investigación, Desarrollo e Innovación (PAIDI 2020)" (ref. PY20_00212, P20_00583), the Spanish Ministry of Economy and Competitiveness through the Spanish National Plan for Scientific and Technical Research and Innovation (ref. PID2020-120157RB-I00 funded by MCIN/ AEI/10.13039/501100011033), and the 'Proyectos I+D+i del Programa Operativo FEDER 2020' (ref. B-CTS-584-UGR20). ToxOmics-Centre for Toxicogenomics and Human Health, Genetics, Oncology and Human Toxicology, is also partially supported by the Portuguese Foundation for Science and Technology (Projects: UIDB/00009/2020; UIDP/00009/2020). The authors declare no competing interests. TRIAL REGISTRATION NUMBER: N/A.

Deficiency of the onco-miRNA cluster, miR-106b∼25, causes oligozoospermia and the cooperative action of miR-106b∼25 and miR-17∼92 is required to maintain male fertility.

The identification of new genes involved in sexual development and gonadal function as potential candidates causing male infertility is important for both diagnostic and therapeutic purposes. Deficiency of the onco-miRNA cluster miR-17∼92 has been shown to disrupt spermatogenesis, whereas mutations in its paralog cluster, miR-106b∼25, that is expressed in the same cells, were reported to have no effect on testis development and function. The aim of this work is to determine the role of these two miRNA clusters in spermatogenesis and male fertility. For this, we analyzed miR-106b∼25 and miR-17∼92 single and double mouse mutants and compared them to control mice. We found that miR-106b∼25 knock out testes show reduced size, oligozoospermia and altered spermatogenesis. Transcriptomic analysis showed that multiple molecular pathways are deregulated in these mutant testes. Nevertheless, mutant males conserved normal fertility even when early spermatogenesis and other functions were disrupted. In contrast, miR-17∼92+/-; miR-106b∼25-/- double mutants showed severely disrupted testicular histology and significantly reduced fertility. Our results indicate that miR-106b∼25 and miR-17∼92 ensure accurate gene expression levels in the adult testis, keeping them within the required thresholds. They play a crucial role in testis homeostasis and are required to maintain male fertility. Hence, we have identified new candidate genetic factors to be screened in the molecular diagnosis of human males with reproductive disorders. Finally, considering the well-known oncogenic nature of these two clusters and the fact that patients with reduced fertility are more prone to testicular cancer, our results might also help to elucidate the molecular mechanisms linking both pathologies.

New insights into the pathogenesis of giant cell arteritis and hopes for the clinic.

Giant cell arteritis is a complex immune-mediated disease that involves large blood vessels in individuals older than 50 years. Recent studies have confirmed a strong association of this form of vasculitis with the HLA region, particularly with HLA class II genes. However, other non-HLA loci, such as protein tyrosine phosphatase non-receptor type 22, may also account for the susceptibility to giant cell arteritis. In addition, genetic variants located in genes encoding proinflammatory cytokines seem to influence the phenotypic expression of the disease, including the risk of severe ischemic complications, the presence of polymyalgia rheumatica and the higher incidence of relapses observed in some patients. The identification of putative genetic markers of disease severity could have clear therapeutic implications, as it may allow us to identify patients who are potentially responders to specific treatments.

Evaluation of a shared autoimmune disease-associated polymorphism of TRAF6 in systemic sclerosis and giant cell arteritis.

OBJECTIVE: We evaluated whether a single-nucleotide polymorphism (SNP) of the TRAF6 gene previously associated with systemic lupus erythematosus and rheumatoid arthritis may be a common risk factor for systemic sclerosis (SSc) and giant cell arteritis (GCA). METHODS: A total of 1185 patients with SSc, 479 patients with biopsy-proven GCA, and 1442 unrelated healthy controls of white Spanish origin were genotyped for the rs540386 variant using a specifically designed TaqMan(©) allele discrimination assay. RESULTS: No significant associations of this SNP with global SSc or GCA were found. This was also the case when the potential associations of the TRAF6 polymorphism with the main clinical phenotypes of the 2 diseases (e.g., limited cutaneous and diffuse cutaneous SSc, or presence of polymyalgia rheumatica and visual ischemic manifestations in GCA) were assessed. CONCLUSION: Our data do not support a role of the rs540386 TRAF6 variant as a key component of the genetic network underlying SSc and GCA.

Autoimmune disease-associated CD226 gene variants are not involved in giant cell arteritis susceptibility in the Spanish population.

OBJECTIVES: CD226 genetic variants have been associated with a number of autoimmune diseases. The aim of this study was to investigate the potential implication of the CD226 loci in the susceptibility to and main clinical manifestations of giant cell arteritis (GCA). METHODS: A Spanish Caucasian cohort of 455 patients diagnosed with biopsy-proven GCA and 1414 healthy controls were included in the study. Three CD226 polymorphisms, rs727088, rs34794968 and rs763361, were genotyped using the TaqMan® allelic discrimination technology. PLINK software was used for the statistical analyses. RESULTS: No significant association between the CD226 polymorphisms and susceptibility to GCA was found (rs727088: p=0.92, OR=1.01, CI 95% 0.86-1.18; rs34794968: p=0.61, OR=1.04, CI 95% 0.89-1.22; rs763361: p=0.88, OR=0.99, CI 95% 0.84-1.16). Similarly, when patients were stratified according to the specific clinical features of GCA such as polymyalgia rheumatica, visual ischaemic manifestations or irreversible occlusive disease, no association was observed either between the case subgroups and the control set or between GCA patients with and without the specific features of the disease. Furthermore, the haplotype analysis revealed no significant association with the clinical manifestations of the disease. CONCLUSIONS: Our results show that the three CD226 polymorphisms analysed do not play a relevant role in the susceptibility to GCA and clinical manifestations of this vasculitis.

A nonsynonymous functional variant of the ITGAM gene is not involved in biopsy-proven giant cell arteritis.

OBJECTIVE: To investigate whether a functional integrin alpha M (ITGAM) variant is involved in susceptibility to and clinical manifestations of giant cell arteritis (GCA). METHODS: A Spanish cohort of 437 white patients with biopsy-proven GCA and 1388 healthy controls were genotyped using the TaqMan allele discrimination technology. RESULTS: No association was observed between ITGAM rs1143679 and GCA (p = 0.80, OR 0.97). Similarly, subphenotype analyses did not yield significant differences between the case subgroups and the control set or between GCA patients with or without the main specific features of GCA. CONCLUSION: Our results suggest that the ITGAM rs1143679 variant does not play an important role in the pathophysiology of GCA.

Role of the CCR5/Δ32CCR5 polymorphism in biopsy-proven giant cell arteritis.

To further explore the potential role of chemokines in giant cell arteritis (GCA), we have studied whether the CCR5/Δ32CCR5 polymorphism is implicated in the susceptibility to the disease and its specific features. A total of 352 Spanish patients with biopsy-proven GCA and 479 matched controls were assessed. DNA was obtained from peripheral blood. Samples were genotyped by PCR with specific primers spanning the 32-bp deletion region. No statistically significant difference in the Δ32CCR5 allele frequency between GCA patients (6.1%) and controls (6.8%) was observed (p = 0.58). This was also the case when the CCR5 /Δ32CCR5 genotype distribution was assessed (p = 0.49). The Δ32CCR5 allele frequency did not differ between patients with or without specific manifestations of the disease, such as polymyalgia rheumatica, visual ischemic manifestations, or irreversible occlusive disease. Hence, our results do not support a potential influence of Δ32CCR5 in the susceptibility to or clinical spectrum of GCA.

The molecular basis of defective lens development in the Iberian mole.

BACKGROUND: Fossorial mammals face natural selection pressures that differ from those acting on surface dwelling animals, and these may lead to reduced visual system development. We have studied eye development in a species of true mole, the Iberian mole Talpa occidentalis, and present the molecular basis of abnormal lens development. This is the first embryological developmental study of the eyes of any fossorial mammal at the molecular level. RESULTS: Lens fibre differentiation is not completed in the Iberian mole. Although eye development starts normally (similar to other model species), defects are seen after closure of the lens vesicle. PAX6 is not down-regulated in developing lens fibre nuclei, as it is in other species, and there is ectopic expression of FOXE3, a putative downstream effector of PAX6, in some, but not all lens fibres. FOXE3-positive lens fibres continue to proliferate within the posterior compartment of the embryonic lens, but unlike in the mouse, no proliferation was detected anywhere in the postnatal mole lens. The undifferentiated status of the anterior epithelial cells was compromised, and most of them undergo apoptosis. Furthermore, beta-crystallin and PROX1 expression patterns are abnormal and our data suggest that genes encoding beta-crystallins are not directly regulated by PAX6, c-MAF and PROX1 in the Iberian mole, as they are in other model vertebrates. CONCLUSION: In other model vertebrates, genetic pathways controlling lens development robustly compartmentalise the lens into a simple, undifferentiated, proliferative anterior epithelium, and quiescent, anuclear, terminally differentiated posterior lens fibres. These pathways are not as robust in the mole, and lead to loss of the anterior epithelial phenotype and only partial differentiation of the lens fibres, which continue to express 'epithelial' genes. Paradigms of genetic regulatory networks developed in other vertebrates appear not to hold true for the Iberian mole.