HLA-DRB5 and Alzheimer disease: In the brain, only four AD loci (CR1, HLA-DRB1/DRB5, IQCK, and MAPT/KANSL1) have significant brain eQTLs of which HLA-DRB1/DRB5 and MAPT/KANSL1 are the only brain ct-eQTLs, noting that all are significant in microglia, neurons, and endothelial cells.