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Hurler syndrome is a rare, inherited disease of metabolism that can damage a person's organs and physical abilities.

Hurler syndrome (MPS1) occurs when the body is unable to make lysosomal alpha-L-iduronidase. This enzyme helps break down gel-like substances called mucopolysaccharides. Mucopolysaccharides are found throughout the body, often in mucus and in fluid around the joints.

In people with Hurler syndrome, mucopolysaccharides build up in the body. This causes symptoms that range from mild to severe. The disease damages many organs, including the heart.

In the past, MPS1 was called Hurler syndrome, Hurler-Scheie syndrome, or Scheie syndrome. Because there is no real difference between the groups, researchers have suggested this classification, based on how severe the disease is:

• Hurler as severe MPS1
• Hurler-Scheie as intermediate MPS1
• Scheie as mild MPS1

Hurler syndrome is inherited, which means that it is passed down from parents to their children. Both parents need to pass down the faulty gene in order for their child to have Hurler syndrome.

Most people develop symptoms of MPS1 between 3 and 8 years of age. Infants with severe MPS1 appear normal at birth. Their facial features may become more coarse during the first 2 years of life. Symptoms include:

• Halted growth
• Progressive mental retardation
• Thick, coarse facial features with low nasal bridge
• Cloudy corneas in the eyes
• Deafness
• Joint disease, including stiffness
• Heart value problems
• Abnormal bones in the spine and claw hand

Tests that may be performed include:

• Urine tests are usually done first. They may show excess MPS when it's present, but they can't determine the exact form of MPS. Enzyme tests must be done to diagnose the disease.
• Alpha-L-Iduronidase tests of blood, skin, or plasma
• Molecular genetic testing for the Alpha-L-Iduronidase (IDUA) gene
• Spine x-ray
• EKG

Enzyme replacement therapy is now possible for patients with a defect in the enzyme alpha-L-iduronidase. A bone marrow transplant can improve some of the symptoms of the disease. To prevent mental retardation, a bone marrow transplant probably should be done at a very young age. Other treatments depend on the organ system that is affected.

For more information and support, contact one of the following organizations:

• The National MPS Society: www.mpssociety.org
• Canadian Society for MPS and Related Diseases: www.mpssociety.ca
• Society for MPS Diseases: www.mpssociety.co.uk

Hurler syndrome is a disease with a poor outlook. Children with this disease develop nervous system problems, and can die young.

Call your health care provider if you have a family history of Hurler syndrome and are considering having children, or if your child begins to show symptoms of Hurler syndrome.

People with a family history of Hurler syndrome who want to have children should have genetic counseling and testing, along with a complete family history profile.

Staba SL, Escolar ML, Poe M, et al. Cord-blood transplants from unrelated donors in patients with Hurler's syndrome. N Engl J Med. 2004 May 6;350(19):1960-9.

National Institute of Neurological Disorders and Stroke. Mucolipidoses Fact Sheet. Office of Communications and Public Liaison. Bethesda, MD; Publication No. 05-4899. February 9, 2005.