GNRH1 and Parkinson disease: To test whether amyloids of long-acting GnRH analogs are able to cross-seed with a protein associated with Parkinson disease, α-Syn, a seeding reaction was done with a small amount of matured L20 fibrils (5% v/v) in the presence of α-Syn (95% v/v; 400 μM concentration of monomeric solution [pH 7.4] in PBS).