GALNS and mucopolysaccharidosis type 3: In vitro studies have suggested that GALNS is inhibited by HS (Rowan et al., 2013), and keratan sulfate, one of the substrates of GALNS, is increased in the serum of Sanfilippo animal models (Rowan et al., 2013) and humans with Sanfilippo syndrome (Tomatsu et al., 2005).