IDS and mucopolysaccharidosis type 2: Our study demonstrated that, seven months post-treatment, AAV8.LSP.IVS2.eBT-IDS4 achieved 89 ​% wild-type IDS activity in the brains of MPS II mice, compared with only 29 ​% achieved by AAV8.LSP.IVS2.IDSco (Fig. 3e).