TABLE 1.

Candidate biomarkers for neurodegenerative disorders transported in exosomes from different human biofluids.

Exosome source	Huntington’s disease	Alzheimer’s disease	Parkinson’s disease	Amyotrophic lateral sclerosis
“Non-specific” exosomes	Absence of mHTT (Denis et al., 2018)	Phosphorylated tau (Saman et al., 2012) ↓REST (Goetzl et al., 2015)	↑miR195 and miR24 ↓miR19b (Cao et al., 2017)	Altered levels of miRNA (Yelick et al., 2020)
NDEs		↑Aβ1-42 ↓Synaptic proteins ↑TDP43 (Fiandaca et al., 2015; Goetzl et al., 2016, 2018; Zhang et al., 2020) ↓synaptophysin, synaptotagmin and SNAP-25 (Goetzl et al., 2016; Agliardi et al., 2019) ↓miR132 and miR-212 (Walsh et al., 2019)	↑DJ1 and α-synuclein (Zhao et al., 2019) ↑α-synuclein and clusterin (Jiang et al., 2020) ↑α-synuclein (Shi et al., 2014; Jiang et al., 2020; Fu et al., 2020; Niu et al., 2020)	Altered levels of miRNA (Katsu et al., 2019; Banack et al., 2020)

NDEs, neuronally derived exosomes; mHTT, mutant huntingtin; REST, repressor element 1-silencing transcription factor; Aβ1-42, amyloid beta-42; TDP43, TAR DNA-binding protein 43; SNAP-25, 25 kD synaptosomal protein; miR, micro RNA.