To determine the effect of glutathione S-transferases M1 and T1 polymorphisms on the risk of senile cataract among Egyptians.The glutathione S-transferases (GSTs) are polymorphic enzymes that are important in the protection against oxidative damage.Using a multiplex polymerase chain reaction (PCR), GSTM1 and GSTT1 gene polymorphisms were evaluated in 53 Egyptians with senile cataract and in 73 healthy individuals of the control group.The frequency of GSTM1-positive individuals among the senile cataract group was significantly higher than in controls. The risk among the GSTM1-positive individuals of developing senile cataract was even higher in females. It is also increased with combination of "GSTM1-positive and GSTT1-positive" genotypes. However the combination of "GSTM1-null, GSTT1-positive" was found to be protective (OR = 0.47; 95 % CI: 0.22-0.99; p = 0.045).The GSTMI-positive genotype and the combined "GSTM1-positive/GSTT1-positive" genotype may be associated with an increased risk of development of senile cataract among Egyptians. However, the "GSTM1-null/GSTT1-positive" genotype was found to be protective. Therefore, when evaluating the role of a particular GST gene in disease susceptibility, the whole pattern of different biotransformation enzymes should be taken into account (Tab. 4, Fig. 1, Ref. 36). Full Text (Free, PDF) www.bmj.sk.