GFAP showed an excellent accuracy in differentiating NB from prodromal AD (AUC = 0.901, accuracy = 85.71% [95% C.I. = 72.75: 98.67], sensitivity = 66.67 [95% C.I. = 49.21: 84.13], specificity = 100%, PPV = 100%, NPV = 80.00 [95% C.I. = 65.18: 94.82]) with a cut-off level of 198.13 pg/mL (Fig. 2). This evidence concerns the gene GFAP and Alzheimer disease.