Mucopolysaccharidosis type IVA (MPS IVA) or Morquio A disease (MPS IVA; OMIM 253000) is a metabolic lysosmal and autosomal recessive disease resulting from the deficiency of the enzyme N-acetylgalactosamine-6-sulfate-sulfatase (GALNS: E.C.3.1.6.4), and the accumulation of undegraded or partially degraded glycosaminoglycans (GAGs): keratan sulfate (KS) and chondroitin-6-sulfate (C6S) in lysosme. Here, GALNS is linked to mucopolysaccharidosis type 4.