well reflect a range of genetic contributions to individual criteria and related traits, Genome Wide Association Studies (GWAS) have been carried out on AD and on individual criteria and related phenotypes. These have identified multiple loci (Walters et al., 2018, Lai et al., 2019a, Lai et al., 2019b, Wetherill et al., 2019, Gelernter et al., 2019, Zhou et al., 2019, Kranzler et al., 2019); however, the functional variants underlying those loci have not been characterized. The genome consists primarily of non-coding SNPs; therefore, it is not surprising that more than 90% of the variants identified by GWAS of complex traits reside in non-coding regions; however, the significant variants are enriched for potential regulatory elements (Maurano et al., 2012).
