APOE and early-onset autosomal dominant Alzheimer disease: Although one of the strongest risk factors for Alzheimer’s disease (both EOAD and LOAD) is being a carrier of the E4 allele of the APOE gene,4 recent genome-wide association studies (GWAS) have shown that variants in more than 50 loci are implicated in LOAD,5 defining LOAD as a polygenic trait.6