Definition:
Individuals who do not fit neatly into the Hurler or Scheie categories are classified as having Hurler-Scheie disease or Hurler-Scheie syndrome. Hurler-Scheie disease is described as a condition with quick disease progression, little or no developmental delay, and symptom severity and mortality in between what is associated with Hurler and Scheie disorders. Medical literature also describes this disorder as being the intermediate form of MPS I.

Hurler-Scheie/MPS I is caused by a mutated gene that manufactures the enzyme, alpha-L-iduronidase. The enzyme, which is needed to break down sugars known as glycosaminoglycans or GAGs, is either produced in very low amounts or is completely absent in individuals affected with this disorder. The sugars are used to build tissues, cartilage, skin, tendons, and joint fluid in the body. Individuals affected with Hurler-Scheie/MPS I have too much GAG in their system. An excessive amount of GAGs result in the clinical symptoms of Hurler-Scheie/MPS I.

This disorder affects one in 100,000 individuals worldwide and approximately one in 25,000 children born in the United States will be afflicted with one of the forms of MPS.

Symptoms:
Symptoms of Hurler-Scheie/MPS I appear between the ages of three and eight. Some of the hallmark symptoms include stiff joints, skeletal abnormalities, clouding of the cornea, an enlarged liver and/or spleen, and coarse facial features. Other symptoms include carpal tunnel syndrome, heart disease, upper respiratory infections, hernias, and lung disease.

Inheritance Pattern:
Hurler-Scheie/MPS I is an autosomal recessive disorder.

Diagnosis and Testing:
A urine test measuring increased levels of glycosaminoglycans (GAGs), the type of sugar chain in the lysosome that accumulate as a result of the malfunctioning enzyme, can detect Hurler-Scheie/MPSI. A urine test is routinely followed by a blood test or skin biopsy, which will show reduced activity of the enzyme alpha-L-iduronidase. Prenatal screening is available to examine alpha-L-iduronidase activity in the fetus. Genetic testing is also available in combination with these diagnostic tests to look for the mutation that causes Hurler-Scheie/MPS I.

Life Expectancy:
Life expectancy for severe Hurler-Scheie/MPS I is late adolescence or pre-teenage years. Individuals affected with a mild Hurler-Scheie/MPS I can live to adulthood.

Treatment:
Treatments for Hurler-Scheie/MPS I include procedures to treat some of the symptoms associated with this disorder as well as its cause. There are many, various treatments aimed at reducing or controlling the symptoms of this disorder. For instance, supplemental oxygen or a tracheostomy may be given to reduce breathing complications. Physical therapy can alleviate the muscle and joint stiffness associated with this disorder. Surgery may also be necessary for a hernia, spinal cord compression, carpel tunnel syndrome, and/or heart valve replacement.

Enzyme replacement therapy has been utilized to help reduce symptoms of this disorder by supplementing or replacing the absent or deficient enzyme. Since the synthesized enzyme does not cross the blood-brain barrier, this therapy will not affect the neurological symptoms associated with Hurler-Scheie/MPS I.

Bone marrow or stem cell transplantation may also be an option for individuals with severe Hurler-Scheie/MPS I.

Patient Groups:
National MPS Society
4220 NC Highway 55, Suite 140
Durham NC, 27713
www.mpssociety.org
tel: (919) 806-0101
fax: (919) 806-2005
Barbara Wedehase, Executive Director
info@mpssociety.org