Definition:
Sanfilippo type C/MPS III C is caused by a mutated gene that manufactures the enzyme acetyl-CoA:alpha-glucosaminide acetyltransferase. This enzyme is needed to break down a specific type of sugar or mucopolysaccharides. The enzyme acetyl-CoA:alpha-glucosaminide acetyltransferase, is either produced in very low amounts or is completely absent. The sugars are used to build connective tissues in the body. Individuals affected with Sanfilippo type C/MPS III C have too many mucopolysaccharides in their system. An excessive amount of these sugars leads to the clinical symptoms of Sanfilippo type C/MPS III C.

There are four types of Sanfilippo/MPS III: A, B, C, and D. There is very little clinical difference in the four different forms of this disorder. The differing characteristic is the mutation of the specific gene that codes for the specific enzyme. The incidence of all four types together is estimated to be one in 70,000 births worldwide.

Symptoms:
Babies born with Sanfilippo type C/MPS III C appear normal, but as more cells become damaged, the signs and symptoms associated with the disorder begin to appear. Symptoms are progressive and classified in stages based upon those presented. Behavioral problems associated with this disorder appear at around two years of age.

In the disorder’s initial stage, the affected child will display delayed speech skills as well as some mild facial abnormalities. In the following stage, the affected child will become extremely active, restless, suffer sleeplessness and exhibit difficult behavior. Many chew on their hands, clothes or on other items. Over time, speech and comprehension will diminish. By age 10, the affected child’s movement will become very limited. In the final stage, the child becomes immobile and generally unresponsive.

Inheritance Pattern:
Sanfilippo type C/MPS III C is an autosomal recessive disorder.

Life Expectancy:
The life expectancy of individuals afflicted with this disorder is 14 to 20 years of age.

Diagnois and Testing:
A urine test is utilized to diagnose Sanfilippo type C/MPS III C. It measures increased levels mucopolysaccharides, the type of sugar chain in the lysosome that accumulates as a result of the malfunctioning enzyme. A urine test is routinely followed by a blood test or skin biopsy, which will reveal reduced activity of the enzyme acetyl-CoA:alpha-glucosaminide acetyltransferase. Prenatal screening is available to examine acetyl-CoA:alpha-glucosaminide acetyltransferase activity in the fetus. Genetic testing is also available in combination with these diagnostic tests to look for the mutation that causes Sanfilippo type C/MPS III C.

Treatment:
There is no cure for Sanfilippo type C/MPS III C. If the disease is caught early, bone marrow transplantation may be beneficial in slowing down the progression of this disorder. In most cases, treatment is limited to reducing or controlling the symptoms of this disorder by making sure that neurologists, ophthalmologists, and genetic counselors are consulted routinely. Medications to control the behavioral problems associated with this disorder have not proven effective. Anti-convulsant medication may control seizures, devices can be inserted in the mouth to assist swallowing, and wheelchairs are often required as the disorder progresses to its final and immobile stage. Genetic counseling is also encouraged.

Other potential treatments include enzyme replacement therapies that cross the blood-brain barrier, therefore allowing the neurological symptoms to be treated. Stem cell transplants are presently under investigation. It is recognized within the medical community that a diagnosis made early in the course of this disorder will render treatment more effective than following a later diagnosis.

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