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As a complex disease, multiple sclerosis (MS) susceptibility implicates many genetic and environmental factors. Usually, individual genetic association studies have several limitations, and results are specific to the population of study. The Meta-analysis approach has been proposed to resolve these limitations and to increase the power of statistical analyses. In this review, we summarize results from meta-analyses of candidate genes of MS. Using the keywords: multiple sclerosis, genetic polymorphism and meta-analysis, we searched electronic databases (PubMed, Embase and Web of Sciences) for published meta-analyses until May 2017. Meta-analyses confirmed the association of polymorphisms in fifteen candidate genes with MS disease. However, polymorphisms in fourteen genes showed none significant association. Results outlined the importance of confirmed genes to understand signaling pathways in MS disease and shed light on their utility to develop new drugs targets. [ABSTRACT FROM AUTHOR]

• IL-26 rs7134599 and rs1558744 SNPs protect against asthma. • The rs2870946 CC genotype was associated with a higher risk of developing asthma in smoking patients. • The combinations of both IL-26 rs7134599 and rs1558744 decrease considerably the risk of asthma. • Over-expression of IL-26 serum levels were detected in patients with uncontrolled asthma. • IL-26 cytokine might contribute to both antiviral and antimicrobial roles in the lungs of asthmatics. The interleukin-26 (IL-26), a member of the IL-10 family is one of the latest discovered cytokines which contributes in numerous chronic autoimmune and inflammatory disorders. In the current case-control study, we investigated the distribution of three IL-26 single nucleotide polymorphisms (SNPs) (rs7134599, rs2870946 & rs1558744) in 440 Tunisian adults via Taqman genotyping assay. The presence of rs7134599 and rs1558744 polymorphisms considerably reduced the risk of developing asthma while the rs7134599 AA [OR = 0.40, CI: 0.23–0.70] and AG [OR = 0.50, CI (0.32–0.76)] genotypes protected against the asthma risk. The rs7134599 A allele was correlated with a lower risk of developing severe asthma (p < 0.001) while that of the rs2870946 CC genotype was associated with a higher risk of developing asthma in smoking patients (p < 0.001). In addition, we measured the IL-26 levels in the serum by an Enzyme-linked-Immunosorbent Assay (ELISA). During the analysis, we found that IL-26 serum levels were incredibly increased in asthmatic patients compared to the healthy controls. Our study revealed a significant association of IL-26 gene polymorphisms with asthma for the first time which can serve as biomarkers for asthma in the Tunisian population. The significant increase of IL-26 serum protein levels in asthma patients suggested a major role of IL-26 in asthma phenotypes. [ABSTRACT FROM AUTHOR]

The 1858T allele in the protein tyrosine phosphatase non-receptor type 22 (PTPN22) locus shows one of the strongest and most consistent genetic associations with autoimmune diseases. We synthesized all meta-analyses reporting a genetic association of the PTPN22 1858T C/T polymorphism with autoimmune diseases. This work examined their validity to discover false positive results under Bayesian methods. We conducted a PubMed search to identify relevant publications and extracted the respective results, published until 30 November 2018. In observational studies, the associations of 1858 C/T genetic variant were noteworthy for 12 autoimmune or autoimmunity-related diseases (rheumatoid arthritis, systemic lupus erythematosus, type 1 diabetes mellitus, juvenile idiopathic arthritis, Crohn's disease, anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis, vitiligo, Graves' disease, myasthenia gravis, Addison's disease, giant cell arteritis, and endometriosis). In contrast, we could not confirm the noteworthiness for eight diseases (systemic sclerosis, psoriasis, Behçet's disease, autoimmune thyroid disease, alopecia areata, Sjögren's syndrome, inflammatory bowel disease, and ankylosing spondylitis). From the meta-analysis of genome-wide association studies (GWAS) with a p-value < 5 × 10−8, findings verified noteworthiness for all autoimmune diseases (psoriatic arthritis, myasthenia gravis, juvenile idiopathic arthritis and rheumatoid arthritis). The results from meta-analysis of GWAS showing a p-value ranging between 0.05 and 5 × 10−8 were noteworthy under both Bayesian approaches (ANCA-associated vasculitis, type 1 diabetes mellitus, giant cell arteritis and juvenile idiopathic arthritis). Re-analysis of observational studies and GWAS by Bayesian approaches revealed the noteworthiness of all significant associations observed by GWAS, but noteworthiness could not be confirmed for all associations found in observational studies. [ABSTRACT FROM AUTHOR]

The human matrix metalloproteinases (MMPs) are importantly involved in aneurysm formation. Since the clinical manifestations in Behçet disease (BD) include aneurysm formation among major symptoms, polymorphisms in MMP-9 might be associated with BD susceptibility. The aim of the current case–control study was to investigate the association of four single nucleotide polymorphisms (SNPs) in MMP-9 gene: -1562 C/T, 2003 G/A (R668Q), 836 A/G (Q279R) and 1721 C/G (R574P) with BD risk in the Tunisian population. The distribution of MMP-9 gene polymorphisms was analyzed by polymerase chain-reaction (PCR) and restriction fragment length polymorphism (RFLP) for 240 BD patients and 288 controls. Our study indicated that the MMP-9 -1562 C/T polymorphism (rs3918242) was not associated with BD risk. We found a significant association of the MMP-9 2003 G/A (rs17577) with an increased susceptibility to BD. However, the MMP-9 1721 C/G polymorphism (rs2250889) had a protective role against the development of BD. Subgroup analysis based on stratification by gender revealed that the MMP-9 2003 G/A polymorphism was associated with a highly significant BD risk in women's group (G vs. A: P = 0.0000001). However, the MMP-9 836 A/G polymorphism had a protective role in men's group (G vs. A: P = 0.00043). The MMP-9 1721 C/G polymorphism was associated with a protective effect in both men and women groups (CG + GG vs. CC: P = 0.04 and P = 0.0002, respectively). The haplotype analysis did not show any association with BD risk. A significant difference in the MMP-9 serum levels were observed in the patient subgroup with ocular lesions manifestations. [ABSTRACT FROM AUTHOR]