Gene expression analysis was performed for APEH and PSMB5 and their related genes, plus other genes typical of parkinsonism or indicative of metabolic alterations: N(alpha)-acetyltransferase (NAA10) Aminoacylase 1 (ACY1), Ubiquitin-activating enzyme 1 (UBA1), Ubiquitin conjugating enzyme E2 I (UBE2I), Parkin RBR E3 ubiquitin protein ligase (PRKN), Alpha-synuclein (SNCA), Parkinsonism associated deglycase DJ-1 (PARK7), and mitochondrial Mn-SOD (SOD2). This evidence concerns the gene UBE2I and Parkinson disease.