GBA1 and sphingolipidosis: In Gaucher disease (GD), a relatively common sphingolipidosis, the mutant lysosomal enzyme acid β-glucocerebrosidase (GCase), encoded by the <i>GBA1</i> gene, fails to properly hydrolyze the sphingolipid glucosylceramide (GlcCer) in lysosomes, particularly of tissue macrophages.