Definition:
MPS VI or Maroteaux-Lamy is a rare disorder that results when an individual has very little or is missing the enzyme Arylsulfatase B (ASB). ASB is used in the lysosome to break down a complex string of sugars known as Glycosaminoglycans (GAGs), often referred to as mucopolysaccharides. In individuals with MPS VI, the GAG accumulates resulting in symptoms of the disorder. GAGS are vital building blocks in the structure of the skin, bones and organs.

MPS VI is very rare, affecting approximately 1,100 people in the “developed” world. There are between 50 and 300 patients afflicted with MPS VI in the United States.

Symptoms:
As more GAG accumulates in the body, symptoms of this disease become more progressive. Similar to other MPS disorders, there is no one hallmark sign or symptom that characterizes MPS VI. The symptoms, widespread in onset, severity and in type, can manifest in early infancy, adolescence or in adulthood, depending upon how much unrecycled GAG accumulates in the cells.

In regard to skeletal symptoms, they can include, short stature, bone abnormalities, stiff joints and coarse facial features. Growth typically stops by the time the affected individual reaches 10 years of age.

Symptoms specific to the organs include an enlarged liver and/or spleen, distended abdomen, hernias and heart murmurs. Other symptoms may include difficulty breathing, noisy breathing, and an increase in ear and sinus infections. Corneal clouding is also a common symptom of MPS VI. Blindness and paralysis can also occur.

Unlike many closely related MPS disorders, MPS VI does not affect intelligence.

Inheritance Patterns:
MPS VI is an autosomal recessive disorder.

Life Expectancy:
Life expectancy is in the teen years for individuals affected with a severe form of MPS VI. Individuals inflicted with a more mild form of the disorder can expect to live longer.

Diagnosis and Testing:
Diagnosis of MPS VI is often delayed or the disease, misdiagnosed. Two tests are used to diagnose MPS VI. A urine analysis measures the amount of GAG in the urine. Individuals with MPS VI have abnormally large amounts of GAG in their urine. An enzyme assay measuring the amount of the enzyme, arylsulfatase B in blood or tissue samples, confirms a diagnosis. Individuals with MPS VI have very low amounts of this enzyme in their cells.

Prenatal diagnosis is also available.

Treatment:
There is no cure for MPS VI but there are many treatments that can be administered to prevent permanent tissue damage, to delay symptom progression and to improve the quality of life for affected individuals.

Physical therapy is often used to improve joint flexibility. Surgery may correct skeletal abnormalities, remove tonsils or improve respiratory problems, chronic ear infections and vision issues.

Stem cell transplants have been used in few cases with limited success. Enzyme replacement therapy is a treatment option that has been used with limited success. Clinical trials show significant improvement with respect to distance walked and stairs climbed in a set amount of time.

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

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