Barrier-stabilizing genes of the claudin family, CLDN5 (p = 0.04, log2FC = 0.71), CLDN18 (p = 0.011, log2FC = 0.47) and CLDN11 (p = 0.019, log2FC = 0.65), were downregulated in AD. This evidence concerns the gene CLDN5 and Alzheimer disease.