Further corrected group comparisons (H(2) = 46.653, p < 0.001) also showed that the P-Tau/Aβ1-42 ratio was comparable (p = 0.370) between the low Aβ1-42 (Md = 0.122, IQR = 0.017–0.172) and grey zone patients (Md = 0.024, IQR = 0.014–0.135), although it was lower in both groups than in the AD group (Md = 0.25, IQR = 0.066–0.353, both p < 0.001). This evidence concerns the gene MAPT and Alzheimer disease.