Although the etiology of PD is complex and not fully understood, key components which may contribute to disease progression have been identified, such as α-synuclein accumulation [15,26], mitochondrial dysfunction, oxidative and endoplasmic reticulum stress [2,4,24,30,31], MHC (major histocompatibility complex) class II driven neuroinflammation [5,24,26], glutamatergic excitotoxicity [1], neuromelanin and iron deposition [32,33,34], and genetic and epigenetic changes [4,35]. The gene discussed is SNCA; the disease is Parkinson disease.