Mucopolysaccharidosis III (MPS III, Sanfilippo syndrome) was described in 1963 by a pediatrician named Sylvester Sanfilippo (J. Pediat. 63: 837-838, 1963, no reference). Mucopolysaccharidosis IIIA (MPS IIIA, Sanfilippo syndrome A, MIM:252900) is a rare, autosomal recessive lysosomal storage disease characterised by severe CNS degeneration in early childhood leading to death between 10 and 20 years of age. 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 and its presence in urine (van de Kamp et al. 1981, Yogalingam & Hopwood 2001, de Ruijter et al. 2011). The gene encoding N-sulfoglucosamine sulfohydrolase, SGSH, was cloned in 1995 (Scott et al.1995) and, later, shown to contain 8 exons spanning approximately 11 kb (Karageorgos et al. 1996).