Mucopolysaccharidosis type IIIC is a neurodegenerative lysosomal storage disorder (LSD) characterized by the accumulation of undegraded heparan sulfate (HS) due to the lack of an enzyme responsible for its degradation: acetyl-CoA:α-glucosaminide N-acetyltransferase (HGSNAT). This evidence concerns the gene HGSNAT and mucopolysaccharidosis type 3C.