The peptides/proteins expressed differently in sera between mild AD patients and control individuals as exhibited in Table 3 and Table 4 were also analyzed for function and phenotype using IPA to potentially identify affected cellular/biochemical pathways and related phenotype/pathological states (Figure 7, top 119 [top 60 from Table 3 plus LTB1, HSPG2, RYR3, MT-ND6---AD related; top 50 from Table 4 plus PTPRQ, TSHZ2, LRP6—AD related; KIF13B, RGS12—ion channel related] out of the 154 proteins in Table 3 and Table 4 present). The gene discussed is PTPRQ; the disease is Alzheimer disease.