CTSD and Alzheimer disease: We, therefore, decided to proceed with the phenotypic characterization of microglia in the 5xFAD/FAAH−/− mouse model, specifically interrogating DAM markers that have been identified as AD risk genes, such as APOE [46] and CTSD [47], and related to microglial phagocytic activity, such as CLEC7A [48], as well.