Mucopolysaccharidosis IVA (MPS IVA or Morquio A syndrome; MIM# 253000) is an autosomal recessive lysosomal storage disorder caused by mutations in the GALNS gene, which encodes for the enzyme N‐acetylgalactosamine‐6‐sulfatase (GALNS; EC 3.1.6.4). The gene discussed is GALNS; the disease is mucopolysaccharidosis type 4A.