PSEN2 and Alzheimer disease: There have been considerable advances in identifying the genetic risk factors for both familial and sporadic forms of AD; in addition to the autosomal-dominant mutations in APP, PSEN1, and PSEN2 that cause early-onset familial AD (Guerreiro et al., 2012), the power of genome-wide association studies (GWAS) and exome sequencing in large sample cohorts (Cruchaga et al., 2014, Guerreiro et al., 2013, Hollingworth et al., 2011, Jansen et al., 2019, Jonsson et al., 2013, Lambert et al., 2013, Sims et al., 2017) has been used to identify both common and rare variants associated with late-onset AD.