The α-synuclein model of PD has been shown to replicate the human pathology more closely than other models [42] Interestingly not all therapeutic interventions that work in other models have been successful in α-synuclein induced models of PD, for example GDNF failed to protect [43], [44] against either WT α synuclien or mutant A30P. Here, GDNF is linked to Parkinson disease.