TREM2 and Alzheimer disease: For example, emerging evidence indicates critical roles for the ITAM-containing receptor triggering receptor expressed on myeloid cells 2 (TREM2), as well as the ITIM-containing receptors sialic acid-binding immunoglobulin-like lectin 3 (CD33) and sialic acid-binding immunoglobulin-like lectin 2 (CD22) in AD (12, , , , , , , , , , , , , , , , , , , , , , –35).