To evaluate the potential for therapeutic effectiveness of intra-CSF AAV9-mediated delivery of IDSspSGSH-IRES-SUMF1, we used the B6Cg-Sgsh(mps3a/PstJ) mouse (Sgsh−/−), a spontaneous MPS-IIIA mouse model largely used in preclinical studies of this disease.24 The gene discussed is SUMF1; the disease is mucopolysaccharidosis type 3A.