| Background:Psoriasis is a disease of polygenic inheritance, psoriasis phenotype can be induced by a variety of factors in susceptible individuals, such as trauma, infection, or drugs. The characteristic lesions are border clear, overlying silvery white scaly red patches. According to clinical features, psoriasis can generally be divided into four types:psoriasis vulgaris、psoriasis pustulose, psoriasis arthropathica. psoriasis erythrodermicum. Research reports that the levels of Tumor necrosis factor alpha (TNF alpha) were increased in the serum and skin lesions of patients with psoriasis. TNF alpha act as one of the key mediators involved in the inflammation process of psoriasis. TNF alpha expression level is influenced by TNF alpha gene polymorphism, therefore TNF alpha gene is an important candidate genes of psoriasis susceptibility genes. Epidemiological studies have investigated the association between TNF alpha gene promoter regions-308loci gene polymorphism and psoriasis susceptibility. Flowever, current results are still controversial. This study collected the past a meta-analysis published related research results at home and abroad, to get to the TNF alpha gene promoter regions-308site gene polymorphism and the association between psoriasis risk more accurate evaluation. To obtain a more precise estimate of the relationship, this meta-analysis was performed.Methods:PubMed、EMBASE、Cochrane library. CNKI、CBMDisc、VIP、Wanfang data were searched for eligible articles. The search strategy to identify all potential studies involved use of combinations of the following key words:("tumor necrosis factor alpha "or" TNF α"or"TNF308G/A "or" rs1800629") and ("polymorphism" or "variant" or "genotype") and ("psoriasis" or "psoriatic"). All related studies published in English and Chinese languages were included. The reference lists of reviews and retrieved articles were hand-searched. The literature search was updated on September2012. The studies included in the meta-analysis must meet all the following inclusion criteria:(1)evaluating the association of-308G/A polymorphism in the TNF-α gene with Psoriasis;(2) providing sufficient data for calculation of odds ratio (OR) with95%corresponding confidence interval (CI);(3) using case-control design;(4) executing Hardy-Weinberg equilibrium in the control group (p＜0.01). Data analysis was performed using STATA version11. A random or fixed effects model was used to calculate pooled OR in the presence or absence of heterogeneity, respectively. The associations of-308G/A polymorphisms in the TNF-α gene with psoriasis was estimated by calculating pooled OR and95%CI under co-dominant, dominant, recessive genetic models and multiplicative model, respectively. Publication bias was assessed by Begg’s funnel plot and by Egger’ s test.Results:The literature search identified24studies met the inclusion criteria and were included in the meta-analysis. A total of3,482cases and2,873controls were identified for the analysis of the association between TNF-α308G/A polymorphism and psoriasis. Overall, the results showed there are significant association between-308G/A polymorphism and decreased risk of psoriasis under three gene comparison models(for A vs. G:OR=0.71,95%CI:0.64-0.80, P＜0.001; for AG vs GG:OR-0.68,95%CI:0.600.77, P＜0.001;for AA+AG vs GG, OR=0.68,95%CI:0.60-0.77, P＜0.001).In the subgroup analysis by ethnicity, significant association was observed in these three models in both Caucasian and Asian. No publication bias was detected among the included studies.Conclusions:TNF α-308G/A polymorphism is associated with decreased risk of psoriasis, and TNF-α-308G/A mutant allele A has a protective effect on psoriasis risk. |
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