Despite being controversial, the results suggest the relevance of pTau in the differential diagnosis of ALS, although with less accuracy than that of NFs.59 In addition, the pTau/tTau (total tau) ratio has been proposed to be correlated with disease progression and survival, as well as severity, as measured by the ALSFRS-R, indicating its potential as a prognostic biomarker.28,60 In fact, the pTau/tTau ratio may be clinically relevant since a reduced ratio is associated with MRI signs of corticospinal tract and grey matter atrophy, as well as upper MN (UMN)-dominant ALS phenotypes.28,59-64. Here, MAPT is linked to amyotrophic lateral sclerosis.