The +252A/G polymorphism in the lymphotoxin-α gene increases the risk of asthma: a meta-analysis. 
A number of studies have shown that the +252A/G polymorphism (rs909253) in the lymphotoxin-α (LT-α) gene is implicated in susceptibility to asthma.  However, the findings have been inconclusive.  The aim of this study was to investigate the association between the +252A/G polymorphism in the LT-α gene and the risk of asthma by performing a meta-analysis.  The Pubmed and Embase databases were searched for all studies relating to this polymorphism and the risk of asthma.  Statistical analyses were performed using the Revman4.2 and STATA 10.0 software.  Thirteen case-control studies that included a total of 2220 cases and 6428 controls were included in the meta-analysis.  There was no significant association between this polymorphism and the risk of asthma in the all-combined analysis (odds ratio (OR) 1.14, 95% confidence interval (CI): 0.89-1.45 for GG+GA vs AA).  In a subgroup analysis by ethnicity, no significant association with asthma risk was identified in Asians (OR 1.31, 95% CI: 0.97-1.77) or Europeans (OR 1.08, 95% CI: 0.77-1.53).  In a subgroup analysis by age, a significantly increased risk was identified among adults (OR 1.25, 95% CI: 1.03-1.50) but not children (OR 1.04, 95% CI: 0.28-3.89).  In a subgroup analysis by atopic status, a significantly elevated risk was identified among atopic (OR 1.55, 95% CI: 1.28-1.87) but not non-atopic individuals (OR 0.94, 95% CI: 0.53-1.68).  This meta-analysis suggested that the +252A/G polymorphism in the LT-α gene is a risk factor for asthma in adults and atopic populations.