Missense mutations in the α-synuclein gene (SCNA) (A53T, A30P and E46K) [9–11] as well as gene multiplications [12–14] cause familial forms of PD, while recent genome wide association studies have revealed polymorphisms in the α-synuclein gene as risk factors for developing sporadic PD [15]. Here, SNCA is linked to Parkinson disease.