Finally, NfL and the NfL/p-tau ratio appeared to be superior to t-tau and the t-tau/p-tau ratio, respectively, in the distinction between prion diseases and AD overall, as well as between atypical/rapidly progressive AD and atypical prion disease, which further validates the diagnostic role of the NfL assay in NDs. The gene discussed is MAPT; the disease is Alzheimer disease.