PICALM and early-onset autosomal dominant Alzheimer disease: Alterations in AP-2 might also be involved in other neurological diseases, because not only PICALM, as discussed in Section 2.4, but also AP2A1 and AP2A2 were identified as gene loci that are linked to Alzheimer’s disease, emphasizing the association of cellular trafficking pathways with Alzheimer’s disease susceptibility [47], even though the exact role of AP2A1 and AP2A2 in Alzheimer’s disease is not clear yet.