Mucopolysaccharidosis type IIIA (MPS IIIA), or Sanfilippo syndrome type A, is a rare neurodegenerative lysosomal storage disorder that typically appears in infancy or early childhood. It affects about 1 in 100,000 births and about 2,500 to 3,000 children globally.

MPS IIIA is caused by mutations in a gene called N-sulfoglucosamine sulfohydrolase (SGSH) that instructs cells to make an enzyme called heparan-N-sulfamidase. This enzyme is responsible for the breakdown and recycling of a large sugar molecule called heparan sulfate. Without sufficient quantities of this critical enzyme, heparan sulfate builds up in cells, disrupting the normal functions of organs, and especially the central nervous system, with severe degeneration of neurons in the brain.


The content provided here is for informational purposes only and is not intended as medical advice, or as a substitute for the medical advice of a physician.

  • Mucopolysaccharidosis Type IIIA (MPS IIIA) is a rare inherited metabolic disorder that primarily affects the brain. MPS IIIA is caused by mutations in the SGSH gene that lead to buildup of large sugar molecules. MPSIIIA is characterized by developmental disabilities and other health problems.

  • Sanfilippo Syndrome Type A is another name for Mucopolysaccharidosis Type IIIA (MPS IIIA), a rare lysosomal storage disorder that causes neurodegenerative symptoms. (See above.)

  • The exact number of people with Sanfilippo Syndrome Type A is unknown but it is estimated to affect approximately about 1 in 100,000 newborns.

  • Sanfilippo Syndrome Type A is caused by mutations in the SGSH gene, which directs production of an enzyme called heparan sulfamidase. This enzyme is needed to break down large sugar molecules called heparan sulfate. A missing or dysfunctional SGSH gene causes an accumulation of heparan sulfate and results in neurodegenerative disease.

  • Mucopolysaccharidosis type IIIA (Sanfilippo Syndrome Type A) is inherited in an autosomal recessive manner, meaning that both parents must pass on an altered gene to their child in order for the disorder to develop.

  • The symptoms of Sanfilippo Syndrome Type A (MPSIIIA) vary widely and can include development and behavioral issues, hyperactivity, increased susceptibility to infections,  sleep disturbance, hearing and vision problems.

  • Depending on the subtype, the median life expectancy of a person with Sanfilippo Syndrome Type A (MPS IIIA) typically ranges from the teens to the twenties.

  • As a first step in diagnosing Sanfilippo Syndrome Type A, a doctor can measure in a patient’s urine the amount of total and individual glycosaminoglycans (GAGs) including heparan sulfate . Although urinary GAG analyses can suggest the most likely type of MPS, diagnosis must be confirmed by an enzyme assay in the blood or skin cells and/or genetic testing. During pregnancy, prenatal testing can detect MPS IIIA.

  • There are currently no cures or approved treatments, which is why Lysogene is committed to developing therapies and bringing them to market.

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