CD33 and early-onset autosomal dominant Alzheimer disease: The importance of neuroinflammation and microglia in Alzheimer’s disease has been highlighted by multiple GWAS, which have identified a number of single polymorphisms associated with risk for development of Alzheimer’s disease in several immune related genes, including TREM2, CD33, BIN1, and CR1 (Efthymiou and Goate, 2017).