The stratified LD plots showed that AD patients manifested a distinct genomic structure relative to NC groups, as represented by stronger LD (i.e., larger pairwise r2 values between variants) among risk variants in the PVRL2, APOE, and APOC1 loci, suggesting that these AD risk variants are more likely to coexist in AD (Fig. 2a). Here, APOC1 is linked to Alzheimer disease.