CTSA and mucopolysaccharidosis type 3C: We further show that NEU1 deficiency in 2 models of MPS IIIC, KO, Hgsnat-Geo mouse (4) and the more severely affected knock-in HgsnatP304L mouse (14) is caused by HS-mediated dissociation of its complex with other lysosomal enzymes—cathepsin A (CTSA), β-galactosidase (GLB1), and glucosamine-6-sulfate sulfatase (GALNS)—known as lysosomal multienzyme complex (LMC).