The current case suggests that tau gene analysis should be undertaken in individuals with a phenotype initially suggestive of AD who develop signs suggestive of PSP, as well as in patients with a diagnosis of “young-onset familial AD” who prove negative for mutations in genes deterministic for AD (amyloid precursor protein, presenilin 1 and 2) [22]. The gene discussed is MAPT; the disease is supranuclear palsy, progressive, 1.