APOE and Alzheimer disease: In addition, the levels of IAPPO-IgA and IAPPM-IgA in APOE4-carrying AD patients were significantly lower compared with AD patients not carrying the APOE4 allele (12.16 ± 7.14 vs. 29.46 ± 6.67, p < 0.001 and 5.95 ± 3.48 vs. 10.84 ± 5.72, p = 0.009, respectively).