Mucopolysaccharidosis (MPS) is a group of inherited metabolic disorders caused by the deficiency of lysosomal enzymes. These enzymes are responsible for breaking down complex sugars called glycosaminoglycans (GAGs). Without these enzymes, GAGs accumulate in the body’s cells and tissues, leading to a wide range of symptoms. There are seven types of MPS, each caused by a deficiency of a different enzyme.