HLA-DRB1 and Alzheimer disease: In addition to the genes associated with innate immune response, the second subgroup includes MHC class II genes HLA-DQA1 and HLA-DRB1 and some genes that regulate the formation of germinal centers and the production of autoantibodies (PHF14 and PLEKHA1) (Sharma et al., 2018; Zhang et al., 2020), which suggests a possible involvement of adaptive immunity in cognitive impairment associated with both COVID-19 and AD.