In a mouse model for another lysosomal disease, MPS II, treatment with HSPC-LVGT expressing iduronate sulfatase (IDS) or epitope tagged IDS (IDS.ApoE2) also resulted in a lack of correlation between IDS enzyme activity in tissue lysates and in clearance of glycosaminoglycans in the brain.93 The gene discussed is IDS; the disease is Lysosomal disease.