Mucopolysaccharidosis type IVA (MPS IVA, also called Morquio Syndrome type A; OMIM 253000) is an autosomal recessive disorder caused by a deficiency of the lysosomal enzyme N-acetylgalactosamine-6-sulfate sulfatase (GALNS) [1,2,3,4,5,6]. Here, GALNS is linked to mucopolysaccharidosis type 4A.