The intensity of monochlorobimane staining of Gaucher disease [median 77% of control values (IQR 50–90%), Mann-Whitney U-test P = 0.001] and Parkinson’s disease with GBA mutation fibroblasts [median 72% (IQR 50–92%) of control, P = 0.001] was significantly less than that of control fibroblasts. This evidence concerns the gene GBA1 and Gaucher disease.