Blood gene expression profiling of neurologic diseases: a pilot microarray study.

BACKGROUND: Tissue gene expression profiling with arrays measures the transcription of thousands of genes. However, this approach cannot be readily used to guide clinical neurologic practice.

OBJECTIVES: To determine whether clinical neurologic diseases are associated with unique patterns of up- and down-regulated genes in whole blood and to explore the possibility of using peripheral blood as a surrogate tissue in these diseases.

DESIGN: Case-control study.

SETTING: University-based pediatric and adult neurology clinics.

PARTICIPANTS: Patients with neurofibromatosis type 1, epilepsy, or Tourette syndrome diagnosed using traditional clinical criteria; controls without disease; and controls with neurologic disease.

MAIN OUTCOME MEASURE: Blood gene expression levels of greater than 12,000 genes, measured using U95A arrays.

RESULTS: Neurofibromatosis type 1 and childhood epilepsy treated with carbamazepine or valproic acid are associated with distinct patterns of blood gene expression. Patients with valproic acid-responsive vs valproic acid-refractory epilepsy formed distinct subclusters. Tourette syndrome was characterized by several gene expression clusters. In 1 cluster, 6 genes-all associated with immune cell function-were overexpressed.

CONCLUSION: Blood gene expression profiling can provide surrogate markers for neurologic diseases without obvious blood phenotypes.