Glutathione S-transferase Genes Variants and Glioma Risk: A Case-control and Meta-analysis Study

The glutathione S-transferase (GST) genes encode enzymes that metabolize carcinogenic compounds, and their variants, (Ile105Val and Ala114Val), (null/present) and (null/present) reduce enzyme activity that may affect the risk of developing cerebral glioma. This study undertook a case-control study and a meta-analysis to evaluate associations between these GST gene variants and the risk of glioma. The study enrolled 384 glioma patients (194 men and 190 women; mean age, 48.3 ± 9.2 years) and 340 healthy controls (174 men and 166 women; mean age, 46.5 ± 9.8 years). The amplification refractory mutation system assay was performed to identify GST gene variants of all 724 subjects. A meta-analysis enrolled 15 studies (including our case-control results) was performed. Our case-control study found that the frequency of Ile105Val Val/Val genotype was significantly higher in the glioma group than that in the healthy controls (11.7% 6.4%) (OR=1.50; 95% CI=1.05-2.04; P=0.01); the frequency of the Val/Ile + Ile/Ile genotypes was different from glioma patients and controls (88.3% 93.6%) (OR=1.47(1.04-2.10); P=0.015); there were no associations between Ala114Val, (null/present) and (null/present) variants and glioma risk. Our meta-analysis confirmed that the Ile105Val variant was associated with an overall increased glioma risk. Moreover, our meta-analysis also confirmed the Ala114Val and null/present variants were associated with an increased glioma risk in the Caucasian population, rather than the Asian population. This study showed that GST gene variants were associated with an increased risk of glioma with ethnic differences. Future large-scale, multi center, controlled, prospective studies are required to support these findings and to determine how these GST gene variants may affect the pathogenesis of glioma.