GBA1 and Parkinson disease: In the GBA1 cohort, we report that: (i) baseline BMP levels are elevated, but only in the N409S+ carriers; although the magnitude of the increase is significantly smaller than that in the LRRK2 cohort (ii) there is no difference in BMP levels between N409S+ PD and N409S+ NMC, and (iii) baseline BMP levels are not associated with longitudinal changes in DaT, MDS-UPDRS III OFF or MoCA.