Since GCase mutations such as N370S and L444P are known to unfold in the ER, induce the UPR, and effect ER calcium homeostasis (Mu et al., 2008, Ron and Horowitz, 2005), it is likely that some of the changes in ER calcium handling observed in both GD and PD lines with heterozygous GBA mutations are related to this. Here, GBA1 is linked to Parkinson disease.