GBA1 and Parkinson disease: To highlight that cautionary note, the selection of PD patients carrying specific GBA mutations did not save the Ven-glustat trial from failure, with the unexpected finding that those allocated to active treatment and carriers of a less severe GBA mutation had a greater progression on efficacy outcomes (Peterschmitt et al., 2021a,b), again bringing attention to the complexity and multifactorial nature of the problem.