Similarly, exonic deletion or duplication mutations in PARK2 (the gene that encodes parkin) are linked with Parkinsonism with daily variations whereas genomic duplications in SNCA (the gene that encodes α-synuclein) or prevalent Ala30Pro and Ala53Thr substitutions cause nigral neuronal loss [17],[18]. This evidence concerns the gene PRKN and Parkinson disease.