Genetic studies link multiple genes to AD development; including amyloid precursor protein (APP), Presenilin 1 (PSEN1), Presenilin 2 (PSEN2), apolipoprotein E (ApoE), and Triggering Receptor Expression on Myeloid cells 2 (TREM2), along with others (81). This evidence concerns the gene PSEN2 and Alzheimer disease.