GNS and mucopolysaccharidosis type 3D: For the MPS IIID (Sanfilippo syndrome type III D, Online Mendelian Inheritance in Man no. 252940), Kresse et al and Beesley et al defined the enzymatic defect in the GNS gene on chromosome 12q14.3, which encodes for the N-acetyl-glucosamine-6-sulfatase.[5, 6]