GBA1 and Parkinson disease: The link between GCase and PD was first established when studies found an increased prevalence of PD in GD patients and their relatives.[14, 15, 16] Carriers of GBA1 mutations exhibit an up to 20‐fold increased risk of developing PD, making GBA1 one of the highest genetic risk factors.[17, 18] The most common PD‐associated GCase variants are p.N370S and p.L444P,[3, 19] which are also prevalent in GD, and p.E326K, a variant that does not appear to cause GD.[20] All three variants are characterized by compromised stability and/or enzyme activity.