GBA1 and Parkinson disease: It is the case for the AMBITIOUS study, a multicentre, randomised, double-blind, placebo-controlled clinical trial investigating whether the prolonged administration of ambroxol can change glucocerebrosidase (GBA) enzyme activity and alpha-synuclein levels in PD patients with GBA mutations.2 This aspect must be disclosed to patients, particularly when considering early-DBS.