Microarray analysis in Tourette syndrome postmortem putamen John J. Hong a , Christopher R. Loiselle a , Dustin Y. Yoon a , Olivia Lee a , Kevin G. Becker b , Harvey S. Singer a,c, * a Department of Neurology, Johns Hopkins University School of Medicine, Jefferson Street Building 124, 600 North Wolfe Street, Baltimore, MD 21287-1000, United States b DNA Array Unit, Research Resources Branch, National Institute on Aging, National Institute of Health, 333 Cassell Drive, Baltimore, MD 21221-6825, United States c Department of Pediatrics, Johns Hopkins University School of Medicine, Jefferson Street Building 124, 600 North Wolfe Street, Baltimore, MD 21287-1000, United States Received 1 December 2003; received in revised form 18 May 2004; accepted 24 June 2004 Available online 25 August 2004 Abstract 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 ( Pb0.1, two-tailed, for Z test; Pb0.05 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. D 2004 Elsevier B.V. All rights reserved. Keywords: cDNA microarray; Tourette syndrome; Postmortem tissue; Putamen; Z test; Z ratio; Protein tyrosine phosphatase 1. Introduction Tourette syndrome (TS) is a complex neuropsychological disorder characterized by childhood onset of chronic motor and vocal tics that have a waxing and waning course [1]. The exact neuroanatomical localization of TS remains unknown, but there is strong evidence for involvement of cortico- striatal–thalamo-cortical (CSTC) circuits [2–4]. The distri- bution of classical neurotransmitters within CSTC pathways has raised the possibility that a single neurotransmitter—or multiple neurotransmitters—may be involved in the patho- biology of this syndrome. Numerous scientific approaches have been pursued to identify abnormalities at the cellular level, including: neurochemical studies on postmortem tissues, cerebrospinal fluid (CSF), blood, and urine; positron and single-photon emission tomography; and genomic analyses in affected populations. Nevertheless, these approaches have failed to delineate a definitive defect; therefore, we sought new options that might generate hypotheses, rather than being restricted to a specific proposal or laboratory methodology. Microarrays are used to survey the expression of thousands of genes in a single experiment. As such, the technology identifies which genes are being used (upregu- lated or downregulated) in a particular tissue at a certain 0022-510X/$ - see front matter D 2004 Elsevier B.V. All rights reserved. doi:10.1016/j.jns.2004.06.019 * Corresponding author. Division of Pediatric Neurology, Johns Hopkins Hospital, Jefferson Street Building 124, 600 North Wolfe Street, Baltimore, MD 21287-1000. Tel.: +1 410 955 7212; fax: +1 410 614 2297. E-mail address: hsinger@jhmi.edu (H.S. Singer). Journal of the Neurological Sciences 225 (2004) 57 – 64 www.elsevier.com/locate/jns