GALNS and mucopolysaccharidosis type 4A: Mucopolysaccharidosis type IVA (MPS IVA, so-called Morquio syndrome type A) (OMIM 253000) is an autosomal recessive inherited disorder and one of the common lysosomal diseases (LSDs), caused by the deficiency of lysosomal hydrolase, N-acetylglucosamine-6-sulfate sulfatase (GALNS) enzyme (EC 3.1.6.4) [1,2,3,4].