HLA-DRB5 and early-onset autosomal dominant Alzheimer disease: HLA-DRB5 (Major Histocompatibility Complex, Class II, DR Beta 5), whose expression products play a central role in the immune system by presenting peptides derived from extracellular proteins, was found to have a possible pathogenic effect Alzheimer’s disease (AD) risk (Karch and Goate, 2015).