Hurler syndrome, also known as mucopolysaccharidosis type I (MPS I) or "Hurler's disease", is a genetic disorder that results in the deficiency of alpha-L iduronidase, which is an enzyme that breaks down mucopolysaccharides. Without this enzyme, the buildup of heparan sulfate and dermatan sulfate occurs in the body (the heart, liver, brain etc.). Symptoms appear during childhood and early death can occur due to organ damage.