MAPT and Alzheimer disease: Moreover, the detrimental action we found on retinal synaptic and mitochondrial functions exerted in vivo by tau truncation fits well with investigations referring a pivotal role of AD-like site-specific hyperphosphorylation at serine 396 (S396) and 404 (S404) and threonine 205 (T205) and 231 (T231) of protein, in causing the visual deficits associated with diabetic retinal neurodegeneration [108].