Interestingly, enteric neurons were also associated with Parkinson’s disease. This result is in line with prior evidence implicating the gut in Parkinson’s disease. Notably, dopaminergic defects and Lewy bodies (i.e. abnormal aggregates of proteins enriched in α-synuclein) are found in the enteric nervous system of patients affected by Parkinson’s disease 65,66. In addition, Lewy bodies have been observed in patients up to 20 years prior to their diagnosis 67 and sectioning of the vagus nerve (which connects the enteric nervous system to the central nervous system) was shown to reduce the risk of developing Parkinson’s disease 68. Therefore, our results linking enteric neurons with Parkinson’s disease provides new genetic evidence for Braak’s hypothesis, which postulates that Parkinson’s disease could start in the gut, travel along the vagus nerve, and affect the brain years after disease initiation38.
