TREM2, a single-pass transmembrane receptor, undergoes proteolytic processing and the soluble variant of TREM2 (sTREM2) is released from the cell via shedding by ADAM protease following proteolytic processing.183 sTREM2 can be detected in human plasma and CSF,184–186 and clinical evidence showed that sTREM2 is becoming a valuable marker of AD pathology and cognitive decline. Here, TREM2 is linked to Alzheimer disease.