Parkinson's disease, pesticides, and glutathione transferase polymorphisms

Background Parkinson's disease is thought to be secondary to the presence of neurotoxins, and pesticides have been implicated as possible causative agents. Glutathione transferases (GST) metabolise xenobiotics, including pesticides. Therefore, we investigated the role of GST polymorphisms in the pathogenesis of idiopathic Parkinson's disease. Methods We genotyped by PCR polymorphisms in four GST classes (GSTM1, GSTT1, GSTP1, and GSTZ1) in 95 Parkinson's disease patients and 95 controls. We asked all patients for information about pesticide exposure. Findings The distribution of the GSTP1 genotypes differed significantly between patients and controls who had been exposed to pesticides (controls vs patients: AA 14 [54%] of 26 vs seven [18%] of 39; AB 11 [42%] of 26 vs 22 [56%] of 39; BE 1 [4%] of 26 vs six [15%] of 39; AC 0 vs four [10%] of 39, p=0.009). No association was found with any of the other GST polymorphisms. Pesticide exposure and a positive family history were risk factors for Parkinson's disease. Interpretation GSTP1-1, which is expressed in the blood-brain barrier, may influence response to neurotoxins and explain the susceptibility of some people to the parkinsonism-inducing effects of pesticides.