SNCA and Parkinson disease: Duplication, triplication, and rare mutations (A53T, A30P, E46K, H50Q, G51D, and A53E) in the SNCA gene, encoding the α-syn protein, have been found in families with dominantly-inherited PD and are associated with early-onset forms, with an amplification of α -syn aggregation [4,5,6,7].