N-sulfoglucosamine sulfohydrolase (SGSH) belongs to the sulfatase family and catalyses the cleavage of N-linked sulfate groups from the GAGs heparin sulfate and heparin. The active site is characterized by the amino-acid sequence motif C(X)PSR that is highly conserved among most sulfatases. The cysteine residue is post-translationally converted to a formylglycine (FGly) residue, which is crucial for the catalytic process. Loss of function of SGSH results a disease called mucopolysaccharidosis type IIIA (Sanfilippo A syndrome), a fatal childhood-onset neurodegenerative disease with mild facial, visceral and skeletal abnormalities.