Parkinson disease (PD) is a progressive neurodegenerative disorder that is characterized by the preferential loss of dopaminergic neurons in the substantia nigra pars compacta (SNpc)(Moore et al., 2005) and the formation of intracytoplasmic protein aggregates, termed Lewy bodies, a major component of which is α-synuclein (α-syn) (Spillantini et al., 1997). The gene discussed is SNCA; the disease is Parkinson disease.