MPS IIIa (N-sulfoglucosamine sulfohydrolase deficiency), MPS IIIb (α-N-acetylglucosaminidase deficiency), MPS IIIc (heparan α-glucosaminide N-acetyltransferase deficiency) and MPS IIId (N-acetylglucosamine-6-sulfatase deficiency) patients all display an altered degradation process of the glucosamine derivatives and should theoretically give rise to diagnostic dp1 NREs and possibly trisaccharides composed of glucosamine derivative-UA-glucosamine. Here, GNS is linked to mucopolysaccharidosis type 3C.