Objective: To analyse the association genetic polymorphisms of glutathione S-transferase (GST) M1 and T1 with genetic susceptibility to sporadic colorectal adenocarcinoma (SCRAC).
Methods: All subjects are unrelated the Han people in Hubei province of China. Using multiple PCR, we studied the genetic polymorphisms of the GSTM1, GSTT1 genes of 101 healthy controls and 104 SCRAC patients.
Results: (1) All the differences of the frequency of GSTM1 null genotype between SCRACs and the controls, between proximal and distal SCRACs and between the elder and the younger SCRACs did not reach statistical significance. (2) The differences of the frequency of GSTT1 null genotype between SCRACs and the controls did not reach statistical significance too; But the null genotype for GSTT1 was significantly more common among distal SCRACs when compared with the proximals (66.2%:44.4%, chi(2) = 3.97, P < 0.05) and more common among the elder SCRACs when compared with younger SCRACs (70.9%:49.0%, chi(2) = 5.21, P < 0.05). (3) Subjects carring both of the null genotypes for GSTM1 and GSTT1 had more than 4.33-fold risk for developing SCRACs compared with the subjects caring both of the nonull genotypes for GSTM1 and GSTT1 (OR = 4.33, 95% confidence interval, 1.56 - 12.04).
Conclusions: (1) There was no association the susceptibility to SCRAC with GSTM1 or GSTT1 null genotype alone, but the date suggests GSTT1 null genotype may influence the distal SCRAC, especially the elder; (2) The individual with both of the null genotypes of GSTM1 and GSTT1 increases markedly the risk of SCRAC, and this genotype is the susceptibility gene to SCRAC.