We also investigated the effects of APOE genotype on the levels and activity of the CSF biomarkers on a subgroup of 93 patients for whom this information was available (AD, n = 18; MCI-AD, n = 30; pre-AD, n = 9; MCI, n = 12; CTRL, n = 17; FTD, n = 7) (Fig. 3). This evidence concerns the gene APOE and Alzheimer disease.