CCL2−2518 (A/G) polymorphisms and tuberculosis susceptibility: a meta-analysis [Review article]

BACKGROUND: It has been found that the −2518 C-C motif ligand (CCL)-2 promoter variant increases the risk of developing active tuberculosis (TB).OBJECTIVE: To study the association between −2518 variants and susceptibility to TB.DESIGN: We searched Medline, PubMed and the Wan Fang databases for human genetic studies on whether the −2518 CCL2 polymorphism influences the expression of active TB. Articles published from January 1998 to November 2010 were included. A random effects model was conducted in the meta-analysis.RESULTS: The CCL2−2518G allele (OR 1.51, 95%CI 1.11-2.04, P = 0.008) showed significant association with susceptibility to TB. In genotype analysis, the recessive model (CCL2 genotype GG, OR 1.66, 95%CI 1.19-2.33, P = 0.003) was slightly superior to the dominant model (G carrier genotypes OR 1.53, 95%CI 1.07-2.17, P = 0.018). These observations were prominent among Asians and Latin-Americans of Hispanic ancestry, but not in Africans from Ghana and South Africa. The presence of epistatic genes in one population but not in the other, environmental differences and pathogen virulence may account for this.CONCLUSION: The CCL2−2518G allele increases the risk of developing TB in Asians and Hispanics.