All biomarkers which are currently available, such as 14-3-3, total tau (tau), S-100 calcium-binding protein B, alpha-synuclein or neuron specific enolase, and the recently established in vitro protein misfolding amplification assays, real-time quaking-induced conversion (RT-QuIC), have a good accuracy for sporadic CJD (sCJD) diagnosis [8,9,10,11,12,13,14,15,16,17,18], but they have not yet been validated adequately for different groups of genetic prion diseases. The gene discussed is MAPT; the disease is sporadic Creutzfeldt-Jakob disease.