N-acetylgalactosamine-6-sulfatase (GALNS) (GALNS)

N-acetylgalactosamine-6-sulfatase (GALNS) is a critical lysosomal exohydrolase responsible for the catabolism of the glycosaminoglycans (GAGs) keratan sulfate and chondroitin-6-sulfate (UniProt: P34059). It functions by removing sulfate groups from the N-acetylgalactosamine-6-sulfate or galactose-6-sulfate residues at the non-reducing ends of these GAG chains. Mutations in the GALNS gene lead to Mucopolysaccharidosis type IVA (MPS IVA), also known as Morquio A syndrome, a lysosomal storage disorder characterized by the systemic accumulation of GAGs (NIH: GARD). This accumulation primarily affects bone and cartilage, resulting in severe skeletal dysplasia, joint laxity, and potential cardiorespiratory complications. Therapeutic strategies focus on enzyme replacement therapy (ERT) with elosulfase alfa, a recombinant human GALNS enzyme that is internalized into lysosomes via mannose-6-phosphate receptors to restore GAG degradation (FDA: Vimizim Label). Monitoring of urinary keratan sulfate levels is the standard biomarker for assessing treatment efficacy and biochemical response.

Other names

GalNAc6S sulfataseChondroitinsulfataseGalactose-6-sulfate sulfataseN-acetylgalactosamine-6-sulfate sulfataseMPS4A

Elosulfase alfa is a recombinant form of the human enzyme N-acetylgalactosamine-6-sulfatase (GALNS) that is taken up by cells into the lysosomes via the mannose-6-phosphate receptor. Once in the lysosome, it replaces the deficient endogenous enzyme and catabolizes the accumulated glycosaminoglycans, keratan sulfate and chondroitin-6-sulfate, by hydrolyzing the sulfate ester bonds (FDA: Vimizim Label).