In α-syn aggregates of PD patients’ brains, increased sumoylation could be detected, and several studies have indicated that sumoylation could promote α-synuclein pathology [80]; however, other studies have still suggested that sumoylation could relieve α-syn aggregation induced by methamphetamine treatment [81], and non-sumoylated isoforms of α-syn were more aggregation-prone and toxic than other α-syn variants [82]. Here, SNCA is linked to Parkinson disease.