Please list the 4 genes involved in Sanfilippo syndrome, also known as mucopolysaccharidosis III (MPS-III).
Mucopolysaccharidosis type III (MPS III, Sanfilippo syndrome) is a lysosomal storage disorder, caused by a deficiency in one of the four enzymes involved in the catabolism of glycosaminoglycan heparan sulfate. The genes are SGSH, NAGLU, HGSNAT or GNS.