Post-mortem studies of patients with schizophrenia consistently show reduced levels of the mRNA for the 67-kD isoform of glutamic acid decarboxylase (GAD67, encoded by GAD1), a key factor in optimal GABA levels, in the DLPFC of patients with schizophrenia (for review see Lewis et al., 2005). This evidence concerns the gene GAD1 and schizophrenia.