The variants in Cy detoxification genes GSTA1*B (rs3957357), GSTP1 (rs1695) and GSTT1*0 (null allele) were correlated with a higher incidence of grade III-IV GVHD and GSTA1 (rs1051775) a lower incidence of grade III-IV GVHD (Table 3). The gene discussed is GSTP1; the disease is graft versus host disease.