Fresh, frozen tissue samples from the frontal lobe of the cerebral cortex and from the cerebellum were obtained from neurologically normal Caucasian subjects. Genomic DNA was extracted using phenol–chloroform and RNA using Trizol from subdissected samples (100–200 mg). Peripheral blood specimens were collected using PAXgene tubes. RNA was extracted from peripheral blood samples using the PAXgene Blood mRNA kit (Qiagen, Crawley, UK) according to the manufacturer's instructions.
