Missense mutations in the SNCA gene, resulting in the expression of α-synuclein variants (A18T, A29S, A30P, A53T, E46K, H50Q, G51D), as well as duplication and triplication of SNCA, leading to elevated α-synuclein levels, are causative for PD in some familiar forms of the disorder (Fujioka et al., 2014). Here, SNCA is linked to Parkinson disease.