SNCA and Parkinson disease: We propose that the ENS of α-synuclein-overexpressing transgenic A30P mice is more sensitive to A30P α-synuclein than the CNS, confirming the assumption, that the A30P mice either belong to the PNS-first PD category or that we do not yet understand that additional triggers might be responsible for the development of one or the other form of PD.