MAPT and Alzheimer disease: One of the most well-known proteinmisfolding diseases is the neurodegenerative condition known as AD.AD is associated with the formation and accumulation of amyloid-β(Aβ) in the brain as well as tangle formation due to misfoldingof the tubulin associate unit (tau) protein.9−23 Another important misfolding protein, α-synuclein (α-syn),is highly involved in the pathophysiology of PD.