Several additional loci exhibited suggestive association (p < 5 × 10−6) to cortical Aβ levels (Figure 2 and Supplementary Table 1). These loci included SNPs within or near the cell adhesion genes of ITGA6 (integrin, alpha 6; chromosome 2) and ITGA1 (integrin, alpha 1; chromosome 5) as well as SNPs near the insulin signaling pathway gene PIK3R1 (phosphoinositide-3-kinase, regulatory subunit 1; chromosome 5), among others. The association signals at these loci were not reduced after the inclusion of APOE ε4 allele status as a covariate (data not shown).
