GSTO2 and nonpapillary renal cell carcinoma: Regarding GST omega class polymorphisms in ccRCC, haplotype comprised of all three variant alleles (GSTO1*A (rs4925), GSTO2*G (rs156697) and GSTO2*G (rs2297235)) showed significantly higher risk of disease development compared to haplotype consisting of all three referent alleles [29].