Among the transcriptome-wide significant results in the total sample, the most significant expression differences in the APOE ε2/ε3 subgroup (p < 10−3) were observed with C4A, C4B, GFAP and NPNT each of which was up-regulated in AD cases compared to controls (Table 1 and Fig. 1a). Here, C4A is linked to Alzheimer disease.