Mucopolysaccharidosis type VI (MPS VI), or Maroteaux–Lamy syndrome (MIM# 253200), is a rare, inherited, autosomal recessive metabolic disorder caused by low to absent activity of the lysosomal enzyme N-acetylgalactosamine 4-sulfatase (arylsulfatase B; ASB; EC 3.1.6.12) that catalyzes one of the steps of degradation of the glycosaminoglycans (GAGs) dermatan sulfate (DS) and chondroitin 4-sulfate (CS). The gene discussed is ARSB; the disease is metabolic disease.