In the PD group, serum t-tau is directly correlated with both CSF t-tau [F(1, 9) = 16.9, p = 0.003, R2 = 0.7] (B = 0.001, p = 0.003) and p-tau [F(1, 9) = 8.2, p < 0.01, R2 = 0.47] (B = 0.007, p < 0.01); serum Aβ42 is directly correlated with CSF Aβ42 [F(1, 9) = 3.9, p = 0.05, R2 =0.3] (B = 0.005, p = 0.05) (Figure 1); serum Aβ40 is not correlated with CSF Aβ40; serum Aβ42/Aβ40 ratio is not correlated with CSF Aβ42/Aβ40 ratio. This evidence concerns the gene MAPT and Parkinson disease.