In Center Tunisia, where the prevalence of Parkinson disease is 22/100,000, the GSTM1 null genotype increases the disease risk (OR = 5.45, 95% IC 2.90–10.30, p-value = 10−6) that could be amplified by the presence of the GSTT1 null genotype58. This evidence concerns the gene GSTM1 and Parkinson disease.