By using the Aβ42/40 quotient no significant differences in tau plasma levels between normal HC (i.e. Aβ42/40 ≥ 0.09 ratio; 3.49 pg/ml; n = 36) and abnormal SCD (i.e. Aβ42/40 < 0.09 ratio; 3.19 pg/ml; n = 17) could be detected (p = 0.366; Table 3). Here, MAPT is linked to Schnyder corneal dystrophy.