Stepwise conditional analysis on the four most prevalent FLG-null mutations and variants tagging the LCE3B-LCE3C deletion identified one AD-specific locus mapping to FLG, a psoriasis-specific locus mapping to LCE3B-LCE3C, and a locus with opposing effects on both diseases mapping to RPTN (MIM 613259)/HRNR/FLG-AS1 (Figure 3B and Table 2). This evidence concerns the gene RPTN and Alzheimer disease.