Null genotypes at the GSTM1 and GSTT1 genes and the risk of benign prostatic hyperplasia: a case-control study and a meta-analysis.

BACKGROUND

Benign prostatic hyperplasia (BPH) is an age related non-malignant disease diagnosed as lower urinary tract symptoms and prostatic enlargement. Null genotypes in drug detoxification glutathione-S-transferase genes/enzymes, such as GSTT1 and GSTM1 have been reported to increase risk of several cancers including prostate. Meta-analysis on PC also suggested significant impact of GSTM1 null genotype but not that of GSTT1; however, BPH data have not been subjected to meta-analysis.

METHODS

We investigated GSTT1 and GSTM1 genotypes in 429 subjects which included 244 BPH, 51 prostate cancer (PC) patients, and 134 control subjects to find if null genotype in any of the two genes increased the risk of BPH/PC. We also performed a quantitative meta-analysis on 888 BPH cases and 793 controls for GSTM1 and on 890 BPH cases and 793 controls for GSTT1 to assess overall consensus about the impact of null genotypes on BPH risk.

RESULTS

We did not find any significant difference in the distribution of genotypes of either of the two genes between BPH/PC cases and controls; however, double deletion (GSTM1 null + GSTT1 null) increased BPH risk, significantly. Upon meta-analysis, null genotype of GSTM1 but not that of GSTT1 appeared to strongly affect BPH risk.

CONCLUSIONS

In our population, null genotypes of either GSTM1 or GSTT1 do not appear to affect BPH risk; however, the double deletion was significantly associated with BPH. Meta-analysis suggested significant influence of GSTM1 null genotype but not that of GSTT1 on BPH risk.