Mucopolysaccharidosis type VII (MPS 7) is an extremely rare, inherited condition caused by a deficiency of an enzyme called beta-glucuronidase. Normally the enzyme breaks down mucopolysaccharides, however as it is lacking the breakdown does not take place. The incomplete broken down mucopolysaccharides remain stored in cells in the body causing progressive damage. Death in the womb is not uncommen, but if born some babies can show little sign of the disease. However, as more and more cells become damaged, symptoms start to appear.There are no approved treatments for MPS 7, and people with the condition often die in early infancy, but some have lived for several decades.Vestronidase alfa (UX 003) is a novel treatment to replace the missing enzyme in MPS 7 patients. Positive outcomes have been reported following a phase III trial in patients aged five to 35, and another trial is ongoing in patients under the age of five.