SNCA and Parkinson disease: Several genes and genomic regions, including alpha-synuclein (SNCA), parkinRBRE3 ubiquitin protein ligase (PARK2), chromosome 22q11deletion/DiGeorge region, and fragile X mental retardation 1 (FMR1) repeats, may be relevant to the development of both ASD and PD, with converging features related to synaptic function and neurogenesis.