Among top upregulated genes in AD and PSO we observed inflammatory mediators (S100 proteins, defensins, matrix metalloproteinases, IL-1 family cytokines), T helper-related genes (CCL1, CCL18, IL17A, IL22, PI3/Elafin), barrier genes (KRT16, SERPINB4, KLK9, FLG2, LCE5A, CLDN8), and genes involved in tryptophan (trp) metabolism (KYNU). The gene discussed is KLK9; the disease is Alzheimer disease.