IL1R1 and mucopolysaccharidosis type 3A: Overexpression of hIL‐1Ra or global knockout of IL‐1R1 in the MPSIIIA mouse reduced the number of activated microglia and astrocytes, and this decrease was more marked with regard to astrocytosis, indicating that interleukin‐1 is a major driver of astrocytosis in MPSIIIA.