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Mucopolysaccharidosis type IIIB

Other Names for this Disease
  • MPS 3B
  • Mucopoly-saccharidosis type 3B
  • N-acetyl-alpha-d-glucosaminidase deficiency
  • Sanfilippo syndrome B
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Mucopolysaccharidosis type IIIB (MPS IIIB) is an genetic disorder that makes the body unable to break down large sugar molecules called glycosaminoglycans (GAGs, formerly called mucopolysaccharides).[1][2] Specifically, people with this condition are unable to break down a GAG called heparan sulfate.[2] Affected individuals can have severe neurological symptoms, including progressive dementia, aggressive behavior, hyperactivity, seizures, deafness, loss of vision, and an inability to sleep for more than a few hours at a time.[1] MPS IIIB is caused by alterations (mutations) in the NAGLU gene. This gene provides the instructions for producing an enzyme called N-alpha-acetylglucosaminidase, which is needed to completely break down heparan sulfate. MPS IIIB is inherited in an autosomal recessive manner.[2] There is no specific treatment for this condition.[2] Most people with MPS IIIB live into their teenage years, and some live longer.[1]
Last updated: 4/14/2010


  1. Mucopolysaccharidoses Fact Sheet. National Institute of Neurological Disorders and Stroke Website. February 16, 2010; Accessed 4/14/2010.
  2. Chambers D. Sanfilippo syndrome. Medline Plus Web site. May 11, 2009; Accessed 4/14/2010.
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