In brain, Wren et al., 2015, showed a significant alteration in intracellular vesicles trafficking with an accumulation of endosomes and exosomes and a reduction of lysosomes in FTD patients carrying N279K mutation in MAPT. These patients also showed an increase of exosomal proteins in frontal and temporal cortex (Wren et al., 2015). Here, MAPT is linked to frontotemporal dementia.