Among the studies, 44 discussed the association between the GSTM1 polymorphism and PCa risk, 37 were about GSTT1, and 35 were about GSTP1. In all eligible studies, there were 26 studies on GSTM1 genotype of Caucasians, 13 studies of Asians, 3 studies of Africans, 1 study of African-Americans and 1 of mixed populations. The gene discussed is GSTP1; the disease is posterior cortical atrophy.