Gene expression patterns in the postmortem putamen of patients with Tourette syndrome (TS) were investigated using cDNA microarrays. A cDNA neuroarray comprising 1537 genes known to be related to neurological or neuropsychiatric disorders was used to compare patient samples (n=3) with those from control subjects (n=4). Z test and Z ratio were used to analyze results; seven genes were found to be upregulated according to our definition (P<0.1, two-tailed, for Z test; P<0.05 for Z ratio) and three were found to be downregulated. Validation experiments were performed using reverse transcription polymerase chain reaction (RT-PCR) and semiquantitative Western blot analyses. RT-PCR showed concordance with microarray in seven of nine selected genes. In contrast, Western blot analyses performed with five proteins showed that only two of five had similar trends between protein content and level of gene expression. The authors note the inherent difficulty in applying microarray technology to complex neurological disorders such as the TS and conclude that further investigations are required to understand how altered expression of these genes is related to the pathophysiology of the disorder.