GALNS and mucopolysaccharidosis type 4A: Mucopolysaccharidosis type IVA (MPS IVA, Morquio A Syndrome) is an autosomal recessive lysosomal storage disease (LSD) caused by a deficiency in the enzyme N-acetylgalactosamine-6-sulfatase (GALNS) due to a mutation in the GALNS gene located on chromosome 16q24.3 [1].