For functional insight into the disease-specific genes, we performed Ingenuity Pathway Analysis (IPA), revealing significant overrepresentation of TH2 and TH1 signaling, dendritic cell maturation and iCOS-iCOSL signaling in helper T cells in AD, and Interferon signaling, LPS-IL-1-mediated inhibition of RXR function, the Inflammasome pathway and Th17 signaling in PSO. This evidence concerns the gene ICOSLG and Alzheimer disease.