In addition, these minor haplotypes were enriched and more frequently associated with each other in the MCI and AD groups than the NC group (Fig. 2b); thus, these minor haplotypes might contribute to AD, and there might be extended haplotypes spanning the PVRL2–APOE–APOC1 region formed by the combination of the abovementioned minor haplotypes from these three genomic regions. Here, APOE is linked to Alzheimer disease.