GALNS and mucopolysaccharidosis type 4A: Morquio A syndrome (Mucopolysaccharidosis type IVA) (MPS IVA) is a rare inherited metabolic disorder characterized by the defective degradation of keratan sulfate and chondroitin-6-sulfate, due to the abnormal or absent activity of N-acetylgalactosamine-6-sulfatase (GALNS gene) [1].