PD is clinically characterized by the two neuropathological features, the degeneration of innervating A9 dopaminergic neurons from the substantia nigra pars compacta (SNc) to the striatum in the midbrain, and the formation of intracytoplasmic neuronal inclusion bodies, referred to as Lewy bodies that are immunopositive for the alpha-synuclein protein in the neurons that remain [2]. The gene discussed is SNCA; the disease is Parkinson disease.