National Center for Advancing and Translational Sciences Genetic and Rare Diseases Information Center, a program of the National Center for Advancing and Translational Sciences

Mucopolysaccharidosis type IIIB


Other Names:
Mucopoly-saccharidosis type 3B; Sanfilippo syndrome B; N-acetyl-alpha-d-glucosaminidase deficiency; Mucopoly-saccharidosis type 3B; Sanfilippo syndrome B; N-acetyl-alpha-d-glucosaminidase deficiency; MPS IIIB; MPS 3B See More
Categories:
This disease is grouped under:
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: 7/2/2015

This table lists symptoms that people with this disease may have. For most diseases, symptoms will vary from person to person. People with the same disease may not have all the symptoms listed. This information comes from a database called the Human Phenotype Ontology (HPO) . The HPO collects information on symptoms that have been described in medical resources. The HPO is updated regularly. Use the HPO ID to access more in-depth information about a symptom.

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Medical Terms Other Names
Learn More:
HPO ID
Percent of people who have these symptoms is not available through HPO
Aggressive behavior
Aggression
Aggressive behaviour
Aggressiveness
[ more ] 		0000718
Asymmetric septal hypertrophy 0001670
Autosomal recessive inheritance 0000007
Cardiomegaly
Enlarged heart
Increased heart size
[ more ] 		0001640
Coarse facial features
Coarse facial appearance
0000280
Coarse hair
Coarse hair texture
0002208
Dense calvaria
Dense skull cap
0000250
Diarrhea
Watery stool
0002014
Dysostosis multiplex 0000943
Hearing impairment
Deafness
Hearing defect
[ more ] 		0000365
Heparan sulfate excretion in urine 0002159
Hepatomegaly
Enlarged liver
0002240
Hirsutism
Excessive hairiness
0001007
Hyperactivity
More active than typical
0000752
Intellectual disability
Mental deficiency
Mental retardation
Mental retardation, nonspecific
Mental-retardation
[ more ] 		0001249
Joint stiffness
Stiff joint
Stiff joints
[ more ] 		0001387
Juvenile onset
Signs and symptoms begin before 15 years of age
0003621
Ovoid thoracolumbar vertebrae 0003309
Progressive neurologic deterioration
Worsening neurological symptoms
0002344
Recurrent upper respiratory tract infections
Recurrent colds
0002788
Seizure 0001250
Sleep disturbance
Difficulty sleeping
Trouble sleeping
[ more ] 		0002360
Splenomegaly
Increased spleen size
0001744
Synophrys
Monobrow
Unibrow
[ more ] 		0000664
Thickened ribs 0000900
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Last updated: 7/1/2020

Making a diagnosis for a genetic or rare disease can often be challenging. Healthcare professionals typically look at a person’s medical history, symptoms, physical exam, and laboratory test results in order to make a diagnosis. The following resources provide information relating to diagnosis and testing for this condition. If you have questions about getting a diagnosis, you should contact a healthcare professional.

Testing Resources

  • The Genetic Testing Registry (GTR) provides information about the genetic tests for this condition. The intended audience for the GTR is health care providers and researchers. Patients and consumers with specific questions about a genetic test should contact a health care provider or a genetics professional.
  • Orphanet lists international laboratories offering diagnostic testing for this condition.

If you need medical advice, you can look for doctors or other healthcare professionals who have experience with this disease. You may find these specialists through advocacy organizations, clinical trials, or articles published in medical journals. You may also want to contact a university or tertiary medical center in your area, because these centers tend to see more complex cases and have the latest technology and treatments.

If you can’t find a specialist in your local area, try contacting national or international specialists. They may be able to refer you to someone they know through conferences or research efforts. Some specialists may be willing to consult with you or your local doctors over the phone or by email if you can't travel to them for care.

You can find more tips in our guide, How to Find a Disease Specialist. We also encourage you to explore the rest of this page to find resources that can help you find specialists.

Healthcare Resources

Research helps us better understand diseases and can lead to advances in diagnosis and treatment. This section provides resources to help you learn about medical research and ways to get involved.

Clinical Research Resources

  • ClinicalTrials.gov lists trials that are related to Mucopolysaccharidosis type IIIB. Click on the link to go to ClinicalTrials.gov to read descriptions of these studies.

    Please note: Studies listed on the ClinicalTrials.gov website are listed for informational purposes only; being listed does not reflect an endorsement by GARD or the NIH. We strongly recommend that you talk with a trusted healthcare provider before choosing to participate in any clinical study.
  • Orphanet lists European clinical trials, research studies, and patient registries enrolling people with this condition. 

Patient Registry

  • The Lysosomal Disease Network is a team of doctors, nurses, research coordinators, and research labs throughout the U.S., working together to improve the lives of people with this condition through research. The Lysosomal Disease Network has a registry for patients who wish to be contacted about clinical research opportunities.

Support and advocacy groups can help you connect with other patients and families, and they can provide valuable services. Many develop patient-centered information and are the driving force behind research for better treatments and possible cures. They can direct you to research, resources, and services. Many organizations also have experts who serve as medical advisors or provide lists of doctors/clinics. Visit the group’s website or contact them to learn about the services they offer. Inclusion on this list is not an endorsement by GARD.

Organizations Supporting this Disease

Social Networking Websites

  • RareConnect has an online community for patients and families with this condition so they can connect with others and share their experiences living with a rare disease. The project is a joint collaboration between EURORDIS (European Rare Disease Organisation) and NORD (National Organization for Rare Disorders).

These resources provide more information about this condition or associated symptoms. The in-depth resources contain medical and scientific language that may be hard to understand. You may want to review these resources with a medical professional.

Where to Start

In-Depth Information

  • Medscape Reference provides information on this topic. You may need to register to view the medical textbook, but registration is free.
  • The Monarch Initiative brings together data about this condition from humans and other species to help physicians and biomedical researchers. Monarch’s tools are designed to make it easier to compare the signs and symptoms (phenotypes) of different diseases and discover common features. This initiative is a collaboration between several academic institutions across the world and is funded by the National Institutes of Health. Visit the website to explore the biology of this condition.
  • Online Mendelian Inheritance in Man (OMIM) is a catalog of human genes and genetic disorders. Each entry has a summary of related medical articles. It is meant for health care professionals and researchers. OMIM is maintained by Johns Hopkins University School of Medicine. 
  • Orphanet is a European reference portal for information on rare diseases and orphan drugs. Access to this database is free of charge.
  • PubMed is a searchable database of medical literature and lists journal articles that discuss Mucopolysaccharidosis type IIIB. Click on the link to view a sample search on this topic.

Questions sent to GARD may be posted here if the information could be helpful to others. We remove all identifying information when posting a question to protect your privacy. If you do not want your question posted, please let us know.

  1. Mucopolysaccharidoses Fact Sheet. National Institute of Neurological Disorders and Stroke (NINDS). February 23, 2016; https://www.ninds.nih.gov/Disorders/Patient-Caregiver-Education/Fact-Sheets/Mucopolysaccharidoses-Fact-Sheet.
  2. Haldeman-Englert C. Sanfilippo syndrome. MedlinePlus. May 7, 2013; http://www.nlm.nih.gov/medlineplus/ency/article/001210.htm. Accessed 7/2/2015.