MPS IIIA (Sanfilippo syndrome A, mucopolysaccharidosis IIIA, MIM:252900) is a rare, autosomal recessive lysosomal storage disease. A deficiency of the enzyme N-sulphoglucosamine sulphohydrolase (SGSH, MIM:605270), which normally hydrolyses the sulfate group from the terminal N-sulphoglucosamine residue of heparan sulfate (HS) leads to the build up of HS in cells and tissues, characterised by severe CNS degeneration in early childhood leading to death between 10 and 20 years of age.
Four mutations (R74C, R245H, S66W, and 1091delC) are known to be prevalent in Polish (Bunge et al. 1997), Dutch (Weber et al. 1997), Italian (Di Natale et al. 1998), and Spanish (Montfort et al. 1998) populations, respectively. These mutations abolish the activity of SGSH being associated with the classic severe phenotype.