Hurler Syndrome

What is Hurler Syndrome?

Hurler syndrome is a rare disease in which the metabolism is affected and the person cannot break down certain sugar molecules. Hurler syndrome belongs to the group of diseases called mucopolysaccharidosis or MPS. The certain sugar molecules that cannot be broken down are glycosaminoglycans (formerly called mucopolysaccharides). The deficiency in breaking down these sugars causes a buildup of these sugars, heparin sulfate and dermatan sulfate which leads to organ damage. This disease is progressive and is usually fatal.

Hurler syndrome is also known as Hurler, Hurler’s disease, gargoylism, Hurler-Scheie syndrome and Scheie syndrome. Hurler syndrome is named after Gertrude Hurler. She was the first doctor to describe this disease in 1919. Later on Dr. Scheie described more patients with this disease that were affected less than the earlier patients. People that do not fit clearly into the mild end or the severe end of this disease are said to have Hurler-Scheie syndrome. Hurler syndrome does not have a cure. Hurler syndrome is an inherited syndrome. ^{[1, 2, 3, 4]}

Causes

Hurler syndrome is caused by the person’s inability to make a special enzyme called lysosomal alpha L-iduronidase (IDUA). Usually this enzyme helps break down the glycosaminoglycans. When the body cannot break these down they build up and cause organ damage. The symptoms of Hurler syndrome can be mild to severe. Hurler syndrome is inherited. Hurler syndrome is seen in 1 out of 100,000 people. The symptoms of Hurler syndrome are usually first seen in the ages of three and eight years old. ^{[1, 4]}

 

Symptoms

• Spinal bone abnormalities
• Claw like hands
• Corneas become cloudy
• Hard of hearing
• Slowed growth
• Abnormalities with heart (valve problems, coronary heart disease and cardiomyopathy)
• Joint disease
• Stiffness of joints
• Intellectual / learning disability
• Unique coarse facial features (flat face, sunken low nose and bulging forehead)
• Short stature
• Enlarged tongue
• Hernias (umbilical and inguinal)
• Enlarged liver and spleen
• Enlarged skull
• Short enlarged bones
• Pelvis malformations
• Progressive deterioration
• Dwarfism
• Death usually before 10 years old
• Limited language skills
• Retina degeneration
• Carpel tunnel syndrome
• Restricted range of motion
• Widened ribs
• Noisy breathing
• Recurring respiratory/ear infections
• Feeding difficulties
• Bowel problems ^{[1, 2, 3, 4]}

 

Diagnosis

For diagnosis of Hurler syndrome some testing is done. A physical examination will be completed looking for abnormalities. Heart EKG testing will be done to look for heart problems. Genetic testing will be done looking for changes in the IDUA gene. Urinary testing will be done looking for excess mucopolysaccharides, increased levels of heparin sulfate and increased levels of dermatan sulfate. X-rays of the bones and spine will look for skeletal abnormalities. Blood work will be ordered looking for abnormalities. A prenatal diagnosis can be achieved via amniotic fluid testing or biopsies of the placenta. A MRI brain scan may be ordered to look at the brain anatomy. Ultrasound imaging can show any eye problems. ^{[1, 3, 4]}

Differential Diagnosis

• Hunter’s syndrome
• General learning disabilities
• Short height

Treatment

Hurler syndrome can be treated with enzyme replacement therapy. Hurler syndrome bone marrow transplants are sometimes needed by people affected with Hurler syndrome. Palliative treatment with an interdisciplinary team will need to be initiated eventually. Orthopedic surgery is an option for skeletal abnormalities. Other surgeries may be warranted for hernias, removal of the tonsils, cornea transplants and for relief of pressure in the ears. Gene therapy may be available in the future. Support groups are available for the patient and their families. Parents can prevent Hurler syndrome with prenatal genetic testing. ^{[1, 2, 3, 4]}

Prognosis & Life Expectancy

Hurler syndrome has a very poor outcome. Serious neurological problems are often seen. Average Hurler syndrome life expectancy for these patients is 11.6 years of age. Some common causes of death are airway obstruction, heart insufficiency and chest infections. ^{[1, 3]}

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What to read next?

• Fetal Alcohol Syndrome
• Peter Pan Syndrome
• Pfeiffer Syndrome
• Goldenhar Syndrome

Reference List:

1. Medline Plus, Available from: https://medlineplus.gov/ency/article/001204.htm
2. MPS Society, Available from: http://mpssociety.org/mps/mps-i/
3. Patient Info, Available from: http://patient.info/doctor/hurlers-syndrome
4. Wikipedia, Available from: https://en.wikipedia.org/wiki/Hurler_syndrome
5. Pinterest, Available from: https://www.pinterest.com/pin/94646029644897269/ AND https://www.pinterest.com/veeveeen/pathology/
6. Mighty Max Blog Spot, Available from: http://mighty-max.blogspot.ca/2003/08/what-is-hurler-syndrome.html