Full sequence analysis of PSAP in patients suffering RBD—a sign of the prodromal stage of synucleinopathies such as PD [83]—report an association of three different and rare mutations with idiopathic rapid eye movement sleep behavior disorder [83]; however, full sequencing of PSAP was not found to fully support a role for PSAP or SapC in PD patients [84]. This evidence concerns the gene PSAP and Parkinson disease.