MAPT and Alzheimer disease: In patients with neurodegenerative disorders, such as AD, PD, ALS, and ALS/PDC [12], the characteristic proteins associated with each disease (phosphorylated tau, phosphorylated α-synuclein, and phosphorylated TDP-43) are misfolded, which results in the formation of abnormal intracellular protein aggregates, leading to cellular dysfunction and, eventually, neuronal cell death.