Alpha-N-acetylglucosaminidase is a lysosomal enzyme required for the stepwise degradation of heparan sulphate []. Mutations on the alpha-N-acetylglucosaminidase (NAGLU) gene can lead to Mucopolysaccharidosis type IIIB (MPS IIIB; or Sanfilippo syndrome type B) characterised by neurological dysfunction but relatively mild somatic manifestations [].