GBA1 and Parkinson disease: GCase activity was decreased by approximately 50% in the putamen and cerebellum of PD+GBA brains, with both regions showing a significant decrease in GCase protein expression.4 Heterozygous GBA1 KO mice with a similar GCase deficiency do not show an increase in GlcCer or GlcSph in brain up to 6 months of age.10 Because the lipidomic analyses were performed on brain lysates, conceivably substrate accumulation in neurons is being masked by the more numerous glia.