What It Is

Sanfilippo Syndrome is the most common disorder of mucopolysaccharide metabolism and also known as Mucopolysaccharidosis Type III (MPS III).

There are 4 types of Sanfilippo syndrome (types A, B, C, and D), each due to deficiency of a different enzyme. All 4 types are inherited in an autosomal recessive manner and result in an identical clinical syndrome.  Sanfilippo syndrome is characterized by an alteration in the enzyme needed to break down the excess excretion of the heparin sulfate sugar chain.  The accumulation of mucopolysaccharides in the central nervous system and other tissues is another characterization of MPS III.

  • MPS IIIA is caused by the missing or altered enzyme heparan N-sulfatase.
  • MPS IIIB is caused by the missing or deficient enzyme alpha-N-acetylglucosaminidase.
  • MPS IIIC results from the missing or altered enzyme acetyl-CoAlpha-glucosaminide acetyltransferase.
  • MPS IIID is caused by the missing or deficient enzyme N-acetylglucosamine 6-sulfatase.


Children with Sanfilippo Syndrome will experience symptoms differently but most will appear between the ages of 2 and 6 with each symptom ranging from mild to very severe.  

Symptoms can include, a coarsening of facial features, stiffening of the joints, slowing of growth, mental retardation, progressive dementia, aggressive behavior, hyperactivity, seizures, deafness, loss of visionm and sleeping difficulties.

As children reach the ages of 6 to ten, the disease will progress resulting in further loss of motor control and balance, difficulties eating or swallowing, and recurring respiratory infections.  

While most children with Sanfilippo will survive into their teens, some children will survive longer.

Treatments & Therapies

There is currently no cure for Sanfilippo Syndrome.  Treatment is symptomatic and supportive.

  • The description of this disease is provided courtesy of the NIH, and other sources.

  • The information provided on this web site should NOT be used as a substitute for seeking professional medical diagnosis, treatment or care. You should not rely on any information in these pages to replace consultations with qualified health professionals.