SNCA and Parkinson disease: In addition to mutations in the SNCA gene, including point mutations (e.g., A53T [33] and A30P [34]) or gene multiplication mutations [55, 56] in familial PD, posttranslational modification has been suggested to lead to aggregate formation; phosphorylation is a major mechanism of posttranslational modification in addition to truncation [57, 58] and ubiquitination [59].