APOE and early-onset autosomal dominant Alzheimer disease: Since the APOE ∊4 allele increases the risk for late-onset Alzheimer’s disease (AD) compared with the APOE ∊2 and ∊3 alleles (Corder et al., 1993; Farrer et al., 1997), LDLR family has been vigorously studied as a target to explore the complex pathogenesis of AD.