SNCA and Parkinson disease: In addition, the gut microbiota may be an exogenous source for prion-like particles to trigger α-synuclein aggregation.72,215 Several prion-like peptides expressed by gut microbiota have been identified and found to enhance α-synuclein aggregation in enteric neurons.72 However, it still remains unclear if the bacterial peptides are produced in sufficient quantities and the microbiome can induce PD in human beings.