Sanfilippo syndrome

Sanfilippo syndrome

Description, Causes and Risk Factors:

Alternative Name: Type III mucopolysaccharidosis.

Sanfilippo syndrome is an inherited metabolic disease caused by an absence or malfunctioning of certain enzymes needed to breakdown molecules called glycosaminoglycans (GAGs). It is in a group of diseases known as the mucopolysaccharidoses (MPS).

Types May include:

    Sanfilippo A: Most severe type of disorder. Most common in Northwestern Europe. Caused by missing or altered enzyme heparin N-sulfatase. Shortest survival rate among other MPS-III disorders.

  • Sanfilippo B: Most common in Southeastern Europe. Caused by missing or altered enzyme alpha-N-acetylglucosaminidase.

  • Sanfilippo C: Caused by missing or altered enzyme acetyl-CoAlpha-glucosaminide acetyltransferase.

  • Sanfilippo D: Caused by missing or altered enzyme N-acetylglucosamine 6-sulfatase.


Three main stages of the disorder:

    Stage 1: Early mental and motor skill development may be delayed. Marked decline in learning between ages 2 and 6, following by eventual loss of language skills and loss of some or all hearing. Some children may never learn to speak. Difficult to diagnose at this age because children do not appear abnormal.

  • Stage 2: Typically during ages 5 to 10 years. Aggressive behavior, hyperactivity, profound dementia and irregular sleep make the child more difficult to manage. Many children chew on their hands or anything they can get a hold of, a definite safety concern.

  • Stage 3: Typically after the age of 10. Children become increasingly unsteady on their feet and most are unable to walk by age 10. Growth in height usually stops by age 10. Most children are nonverbal by this stage

Sanfilippo syndrome or MPS III can result from four different enzyme deficiencies. These four enzymes are involved in the lysosomal catabolism of heparan sulphate glycosaminoglycans which are heparin-related macromolecules consisting of a chain of carbohydrate monomeric residues, some of which are sulphated. They are involved in growth factors signaling pathways, but their functions are not yet totally elucidated. The eight enzyme involved in the stepwise degradation of heparan sulphate are believed to function in cooperation in an enzymatic complex inside the lysosome, the product of one enzyme being passed to the next one. Although diverse at the genetic and biochemical levels, the clinical manifestations are very similar in the four forms of the disease.

The syndrome is inherited as an autosomal recessive trait. That means both your parents must pass you the defective gene in order for you to get this disease. Sanfilippo syndrome is possibly the most common forms of MPS. It is seen in about 1 in 70,000 births. A family history of Sanfilippo syndrome increases one's risk for this condition.


This disease is marked by severe neurological symptoms, including:

    Progressive dementia.

  • Aggressive behavior.

  • Hyperactivity.

  • Seizures.

  • Some deafness and loss of vision.

  • Decreased intellectual functioning (severe mental retardation).

  • Inability to sleep for more than a few hours at a time.

  • Thickened skin.

  • Mild changes in facial features, bone and skeletal structures.

  • Severe diarrhea or constipation.

  • Liver and spleen enlargement.

  • Narrowing of airway passage in the throat.

  • Enlargement of tonsils and adenoids (difficulty eating andswallowing).

  • Recurring respiratory infections.


Generally, MPS disorders are diagnosed by their main biochemical features, i.e.accumulation of GAGs, detectable in urinary samples, and enzyme deficiencies assays, most of the time measured in patient leucocytes.

The probable diagnosis of all MPS III subtypes is based on increased concentration of heparan sulfate in the urine. Enzymatic assays in leukocytes and/or fibroblasts confirm the diagnosis and allow for discrimination between the different subtypes of the disease.

The genetic diagnosis of this disease is not yet routinely available worldwide, although itis in France, considerable development has beenmade in this domain, leading to a more detailed knowledge of the genetic mutations underlyingthe respective enzymatic deficiency, and the genotype/phenotype relation in the differentdiseases.


Currently, there is no cure for Sanfilippo syndrome. Enzyme Replacement Therapy (ERT) is offered as treatment to some children with MPS disorders. This involves injecting enzymes into the patient to stop or even reverse the storage that causes the disease. Unfortunately, this treatment (ERT) is not beneficial for children with Sanfilippo syndrome because the enzyme administered into the bloodstream is prevented from entering the blood-brain barrier. Umbilical cord blood transplantations are another experimental treatment for children with MPS, but research is still inconclusive as to the benefit for children with Sanfilippo syndrome.

NOTE: The above information is educational purpose. The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition.

Reference and Source are from:

DISCLAIMER: This information should not substitute for seeking responsible, professional medical care.


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