PD can start in the gut, and Multiple System Atrophy can start in the bladder?

[Rhyothemis]

By 'start' I mean the initial site of misfolded alpha synuclein which then propagates through the nervous system. Here's a preprint of a study on mice where they injected alpha synuclein preformed fibrils in the lower urinary tract of mice, which subsequently expressed MSA-like symptoms.

biorxiv.org/content/biorxiv...

"Thus, these findings suggest that pathological α-Syn spreads from the autonomic innervation of the lower urinary tract to extrapyramidal system via the micturition reflex pathways, leading to widespread α-Syn inclusion pathology"