GBA1 and Parkinson disease: GBA1‐related patients with PD have earlier age at onset, higher prevalence of the postural instability, gait‐difficulty phenotype, worse motor symptoms, more frequent non‐motor symptoms, rapid progression, and reduced survival compared with non‐GBA1‐mutated patients with PD (Brockmann et al., 2015; Malek et al., 2018; Maple‐Grødem et al., 2021; Stoker et al., 2020).