CD33 and Alzheimer disease: Summarizing the work of others, Hampel et al. [22] noted that Genome Wide Association Studies (GWAS) identified multiple protein variants involved in AD neuroinflammation: triggering receptor expressed on myeloid cells 2 (TREM2), myeloid cell surface antigen CD33 (CD33), paired immunoglobin-like type 2 receptor alpha (PILRA), complement receptor type 1 (CR1), membrane-spanning 4-domains subfamily A (MS4A), clusterin (CLU), ATP-binding cassette subfamily A member 7 (ABCA7), and ephrin type-A receptor 1 (EPHA1).