In this study, we evaluated the long-term (24–48 weeks) effects of an AAV vector expressing the human GALNS enzyme, driven by a liver-specific human thyroxin-binding globulin (TBG) promoter, in GALNS knockout (KO, Galns−/−) MPS IVA mouse models with a C57BL/6 background. Here, GALNS is linked to mucopolysaccharidosis type 4A.