TNTs allow the spreading and progression of neuronal diseases such as Alzheimer’s disease (AD), Creutzfeldt-Jakob disease (CJD), Huntington’s disease (HD) or Parkinson’s disease (PD) through the intercellular dissemination of their respective pathogenic agents: Tau and amyloid-β aggregates for AD [73,76,135], PrPSc prions for CJD [136], mutant huntingtin aggregates for HD [75,137], and α-synuclein (α-syn) aggregates for PD [74,116,138,139]. The gene discussed is HTT; the disease is Parkinson disease.