Meta-analysis of the TNF-α-308G/A polymorphism and vitiligo risk.

Several case-control studies have been conducted to investigate the association between the tumor necrosis factor-α (TNF-α)-308G/A polymorphism and vitiligo risk. However, the results of these studies are inconsistent; therefore, we attempted to comprehensively evaluate the association between TNF-α-308G/A polymorphism and vitiligo risk via a meta-analysis. Studies reporting the association between TNF-α-308G/A polymorphism and vitiligo risk were retrieved from PubMed and EmBase databases. Data were extracted from these studies and the pooled odds ratios (ORs) with 95% confidence intervals (CIs) were calculated to assess the association. Six case-control studies including 1391 vitiligo cases and 2455 control subjects were included in this meta-analysis. The overall results showed the lack of a significant difference in TNF-α-308G/A genotype distribution between the patients and controls when the G allele and GG, GG + GA, GG, and GG genotypes were compared against the A allele and the GA + AA, AA, AA, and GA genotypes, respectively (ORs = 0.65, 0.53, 0.63, 0.41, 0.55; 95%CI = 0.35-1.23, 0.24-1.18, 0.10-4.09, 0.08-1.97, 0.25-1.21; P = 0.188, 0.121, 0.627, 0.264, 0.135, respectively). This meta-analysis suggests that the TNF-α-308G/A polymorphism may not be associated with vitiligo risk. As few studies are available in this field and current evidence remains limited, these results must be corroborated with well-designed and larger studies in the future.

Association between MTHFR 677C/T polymorphism and psoriasis risk: a meta-analysis.

Previous studies investigating the association between methylenetetrahydrofolate reductase (MTHFR) 677C/T polymorphisms and psoriasis risk have reported inconsistent results. The present meta-analysis aimed to comprehensively evaluate the association between MTHFR 677C/T polymorphism and psoriasis risk. The studies regarding the association between MTHFR 677C/T polymorphism and psoriasis risk were retrieved from the PubMed, Embase, Web of Science, Chinese National Knowledge Infrastructure, and Chinese Biomedical databases. Data were extracted and statistical analysis was performed with the program STATA 12.0. A total of seven studies involving 1290 psoriasis cases and 1068 healthy controls were retrieved. Combined analysis showed that there was no significant difference in MTHFR 677C/T genotype distribution between psoriasis and control subjects in the comparisons C vs T, CC vs CT + TT, CC + CT vs TT, CC vs TT, and CC vs CT [respectively: odds ratio (OR) = 0.98, 95% confidence interval (CI) = 0.76-1.26, P = 0.882; OR = 1.11, 95%CI = 0.81-1.51, P = 0.526; OR = 0.79, 95%CI = 0.53-1.19, P = 0.261; OR = 0.88, 95%CI = 0.51-1.52, P = 0.648; OR = 1.19, 95%CI = 0.90-1.58, P = 0.217]. Subgroup analysis by ethnicity also showed no significant association between MTHFR 677C/T polymorphism and psoriasis risk in both Asian and Caucasian populations. In conclusion, this meta-analysis indicates that MTHFR 677C/T polymorphism may not be associated with psoriasis risk.