Genetic linkage, large-scale genome-wide association, and exome sequencing studies have also repeatedly linked lipid metabolism–related genes/loci and rare variants with AD, including apolipoprotein E (APOE), CLU, ABCA7, SORL1, TREM2, PICALM, INPP5D, and PLCG2 (reviewed in refs. 171–173). Here, APOE is linked to Alzheimer disease.