GBA1 and Parkinson disease: In addition, GBA1 variants—pathogenic or non-causative for GD—are recognized as the most prevalent genetic risk factors for sporadic Parkinson’s disease (PD) [15,16], and the risk for developing PD is higher in GD patients, as well as in heterozygous GBA1-mutation carriers (GBA-PD), than in non-carriers, suggesting common disease pathways of GD and PD [17].