Hurler syndrome is an inherited disorder caused by faulty genes passed on from parents to children. In Hurler syndrome the body is missing an enzyme that breaks down large molecules called glycosaminoglycans (GAG). These molecules help to build bones and tissue. In patients with Hurler syndrome the body cannot break down these large molecules, and result in GAG molecules building up and damaging organs and tissues.
Hurler syndrome occurs in about 1 of every 100,000 babies born. Children with Hurler syndrome have many physical and mental problems. If the damage is not stopped, these children usually die before 10 years of age.
Allogeneic transplant represents an effective therapy for patients with Hurler syndrome. When performed early in the disease course in conjunction with intensive speech therapy, transplantation can preserve intellectual function and prevent severe manifestations of the classic severe Hurler phenotype. What is not altered after successful transplant are the skeletal abnormalities. However, transplantation for children who already have developed severe damage, including decreased intellect, have poor results as the transplant cannot undo damage that has already been done.