MAPT and early-onset autosomal dominant Alzheimer disease: However, recent reports have suggested that CSF p-tau217 is not only increased in Alzheimer’s disease but also in non-Alzheimer’s disease neurodegenerative tauopathies including those harbouring specific disease-associated genetic mutations in the MAPT gene without evidence of Aβ pathology (that is, they have A−T+ profiles that are outside the Alzheimer’s disease continuum).24,25 It is unknown whether plasma p-tau217—a more accessible biomarker than CSF p-tau217—is elevated in A−T+ tauopathies, such as Niemann–Pick disease type C.