In Type 1 GD patients, ambroxol has been shown to be safe and tolerable (ClinicalTrials.gov Identifier: NCT03950050) (97) and results from a phase II, single-centre trial, in PD patients with and without GBA1 mutations, demonstrate that ambroxol can cross the BBB and enter the CSF where it can alter GCase activity and protein level (ClinicalTrials.gov Identifier: NCT02941822) (98). This evidence concerns the gene GBA1 and Parkinson disease.