APOE and Alzheimer disease: In addition, the putative functional similarities between the proteins these genes encode (Kounnas et al., 1995; Koch et al., 2001; Elliott et al., 2010; Leeb et al., 2014) prompted us to explore whether APOE and APOJ polymorphisms may have a cumulative effect, which would suggest the potential of a common pathway for these risk factors in a region critical for AD pathogenesis.