Over the last decade, exosomes have been shown to serve as carriers of other disease-related protein aggregates, such as Aβ and Tau (49, –, 52) in Alzheimer’s disease, α-synuclein in Parkinson’s disease (35, 53, 54), and Cu, Zn superoxide dismutase (SOD1) in a cellular model of amyotrophic lateral sclerosis (ALS) (55, –, 57). Here, MAPT is linked to early-onset autosomal dominant Alzheimer disease.