MAPT and Alzheimer disease: In this framework, since the retinal staining by 12A12mAb is mainly confined to the Ganglion Cell Layer (GCL, the output neurons of the eye) as shown for hyperphosphorylated tau in eyes of tauopathy transgenic models [79] and AD cases [15], the pathogenic N-truncated tau could be exploited as feasible and accessible candidate for the visual exploration of AD pathology by in vivo-imaging techniques [124, 137].