GLB1 and GM1 gangliosidosis: Weekly ICV dosing with rhβ-gal for 8 weeks in GLB1 KO mice also coincides with near-to-complete clearance of two classes of substrates in GM1 gangliosidosis brain tissue, with the GM1 and GA1 ganglioside substrates requiring a longer duration of ERT for maximal clearance, when compared with glycan substrates (Fig. 3, F–I).