Fyn promotes neurotoxicity downstream of both the amyloid-β (Aβ) peptide, which forms extracellular amyloid plaques, and the microtubule-associated protein Tau, which in a hyperphosphorylated form accumulates into neurofibrillary tangles (NFTs), a key hallmark of AD and FTLD-Tau [10]. This evidence concerns the gene FYN and Alzheimer disease.