Role of polymorphisms of GSTM1, GSTT1 and GSTP1 Ile105Val in childhood acute lymphoblastic leukemia risk: an updated meta-analysis

INTRODUCTION: The association between glutathione-S-transferase polymorphisms (GSTM1, GSTT1 and GSTP1 Ile105Val) and risk of childhood acute lymphoblastic leukemia (ALL) remains controversial. Therefore, we performed a meta-analysis to derive a more precise estimation of the relationship. EVIDENCE ACQUISITION: We searched Medline (Mainly Pubmed), Embase, Cochrane Library, CNKI (Chinese National Knowledge Infrastructure), Chinese Biomedical Literature (Chinese) and Wanfang (Chinese) Databases to collect articles that evaluated the polymorphism of GSTs gene in child patients with ALL. We also reviewed reference lists from retrieved articles. Two researchers evaluated study eligibility and extracted the data independently, and disagreements were resolved by discussion. Two reviewers independently assessed the methodological quality of each study. The principal outcome measure was the odds ratio (OR) with 95% confidence interval (CI) for the risk of child ALL associated with GSTM1, GSTT1, GSTP1 Ile105Val. The data were analyzed using Stata (Version 12.0) software. EVIDENCE SYNTHESIS: This meta-analysis included 30 studies for GSTM1 polymorphism, 27 studies for GSTM1 polymorphism and 10 studies for GSTP1 Ile105Val polymorphism. The combined results based on all studies showed that GSTM1 (OR = 1.297, 95% CI = 1.105-1.523, P = 0.001) and GSTT1 polymorphism (OR = 1.213, 95% CI = 1.031-1.427, P = 020) contributes to the development of childhood ALL, while no association was found in all comparison models of GSTP1 Ile105Val variants (homozygote model: OR = 1.234, 95% CI = 0.966-1.578, P = 0.093, heterozygote model: OR = 1.072, 95% CI = 0.931-1.235, P = 0.331, dominant model: OR = 1.104, 95% CI = 0.965-1.262, P = 0.149, recessive model: OR = 1.184, 95% CI = 0.934-1.499, P = 0.162, and allele comparison model: OR = 1.096, 95% CI = 0.988-1.216, P = 0.083). CONCLUSIONS: The current analyses suggests significant association was found between GSTM1 variants and the risk of childhood ALL, while no association were found between GSTT1 and GSTP1 Ile105Val polymorphism and childhood ALL risk.