Parkinson’s disease (PD) is the second most common late-onset neurodegenerative disease after AD and is characterized by an accumulation of α-synuclein—also known as Parkinson disease protein 1 (PARK1)—and mitochondrial dysfunction [122] as well as bradykinesia, rigidity, and tremor due to the loss of dopaminergic neurons in the substantia nigra [123]. The gene discussed is SNCA; the disease is Alzheimer disease.