Hurler syndrome
Alpha-L-iduronate deficiency; Mucopolysaccharidosis type I; MPS I H
Hurler syndrome is a rare disease of metabolism in which a person cannot break down long chains of sugar molecules called glycosaminoglycans (formerly called mucopolysaccharides).
Metabolism
Metabolism refers to all the physical and chemical processes in the body that convert or use energy, such as:BreathingCirculating bloodControlling bo...
Hurler syndrome belongs to a group of diseases called mucopolysaccharidosis, or MPS.
See also:
-
MPS II (Hunter syndrome)
MPS II (Hunter syndrome)
Hunter syndrome is a disease in which long chains of sugar molecules (glycosaminoglycans, formerly called mucopolysaccharides) are not broken down co...
-
MPS IV (Morquio syndrome)
MPS IV (Morquio syndrome)
Morquio syndrome is a disease of metabolism in which the body is missing or does not have enough of a substance needed to break down long chains of s...
-
MPS III (Sanfilippo syndrome)
MPS III (Sanfilippo syndrome)
Sanfilippo syndrome is metabolism disorder in which the body cannot properly break down long chains of sugar molecules. These chains of molecules ar...
-
MPS I S (Scheie syndrome)
MPS I S (Scheie syndrome)
Scheie syndrome is metabolism disease in which the body cannot properly break down long chains of sugar molecules called glycosaminoglycans (formerly...
Causes
People with Hurler syndrome do not make an enzyme called lysosomal alpha-L-iduronidase. This enzyme helps break down long chains of sugar molecules called glycosaminoglycans . These molecules are found throughout the body, often in mucus and in fluid around the joints.
Enzyme
Enzymes are complex proteins that cause a specific chemical change in all parts of the body. For example, they can help break down the foods we eat ...
Without the enzyme, glycosaminoglycans build up and damage organs, including the heart. Symptoms can range from mild to severe.
Hurler syndrome is inherited, which means that your parents must pass the disease on to you. If both parents carry a nonworking copy of the gene related to this condition, each of their children has a 25% (1 in 4) chance of developing the disease.
Hurler syndrome is a type of mucopolysaccharidosis called MPS I. It is the most severe type. It is categorized as MPS I H.
The other subtypes of MPS I are:
- MPS I H-S (Hurler-Scheie syndrome)
- MPS I S (Scheie syndrome)
Symptoms
Symptoms of Hurler syndrome most often appear between ages 3 to 8. Infants with severe Hurler syndrome appear normal at birth. Facial symptoms may become more noticeable during the first 2 years of life.
Symptoms include:
- Abnormal bones in the spine
- Claw hand
-
Cloudy corneas
Cloudy corneas
A cloudy cornea is a loss of transparency of the cornea.
-
Deafness
Deafness
Hearing loss is being partly or totally unable to hear sound in one or both ears.
- Halted growth
- Heart valve problems
- Joint disease, including stiffness
-
Intellectual disability
that gets worse over time
Intellectual disability
Intellectual disability is a condition diagnosed before age 18 that includes below-average intellectual function and a lack of skills necessary for d...
-
Thick, coarse facial features with
low nasal bridge
Low nasal bridge
A low nasal bridge is the flattening of the top part of the nose.
Exams and Tests
These tests are done to check for Hurler syndrome:
-
EKG
EKG
An electrocardiogram (ECG) is a test that records the electrical activity of the heart.
- Genetic testing for changes to the alpha-L-iduronidase (IDUA) gene
- Urine tests for extra mucopolysaccharides
- X-ray of the spine
Treatment
Enzyme replacement therapy for Hurler syndrome adds a working form of the missing enzyme to the body. The medicine, called laronidase (Aldurazyme), is given through a vein (IV, intravenously). Talk to your health care provider for more information.
Bone marrow transplant has been used in several people with this condition. The treatment has had mixed results.
Bone marrow transplant
A bone marrow transplant is a procedure to replace damaged or destroyed bone marrow with healthy bone marrow stem cells. Bone marrow is the soft, fat...
Other treatments depend on the organs that are affected.
Support Groups
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
Outlook (Prognosis)
Hurler syndrome is a disease with a poor outlook. Children with this disease develop nervous system problems, and can die young.
When to Contact a Medical Professional
Call your provider if:
- You have a family history of Hurler syndrome and are considering having children
- Your child begins to show symptoms of Hurler syndrome
Prevention
Experts recommend genetic counseling and testing for couples with a family history of Hurler syndrome who are considering having children. Prenatal testing is available.
References
National Institute of Neurological Disorders and Stroke. Mucolipidoses Fact Sheet . Office of Communications and Public Liaison. Bethesda, MD; Publication No. 03-5115. February 13, 2007.
Pyeritz RE. Inherited diseases of connective tissue. In: Goldman L, Schafer AI, eds. Goldman's Cecil Medicine . 25th ed. Philadelphia, PA: Elsevier Saunders; 2015:chap 260.
Spranger J. Mucopolysaccharidoses. In: Kliegman RM, Behrman RE, Jenson HB, Stanton BF, eds. Nelson Textbook of Pediatrics . 19th ed. Philadelphia, PA: Elsevier Saunders; 2011:chap 82.
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. PMID: 15128896 www.ncbi.nlm.nih.gov/pubmed/15128896 .
Wraith JE. Mucopolysaccharidoses and oligosaccharidoses. In: Saudubray JM, van den Berghe G, Walter JH, eds. Inborn Metabolic Diseases: Diagnosis and Treatment . 5th ed. New York, NY: Springer; 2012:chap 40.
-
Low nasal bridge - illustration
A low or absent nasal bridge can occur in association with infectious diseases or genetic diseases.
Low nasal bridge
illustration
Review Date: 4/20/2015
Reviewed By: Chad Haldeman-Englert, MD, FACMG, Wake Forest School of Medicine, Department of Pediatrics, Section on Medical Genetics, Winston-Salem, NC. Review provided by VeriMed Healthcare Network. Also reviewed by David Zieve, MD, MHA, Isla Ogilvie, PhD, and the A.D.A.M. Editorial team.