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Disease Profile

Mucopolysaccharidosis type IIIB

Prevalence
Prevalence estimates on Rare Medical Network websites are calculated based on data available from numerous sources, including US and European government statistics, the NIH, Orphanet, and published epidemiologic studies. Rare disease population data is recognized to be highly variable, and based on a wide variety of source data and methodologies, so the prevalence data on this site should be assumed to be estimated and cannot be considered to be absolutely correct.
1-9 / 1 000 000

331 - 2,979

US Estimated

1-9 / 1 000 000

514 - 4,622

Europe Estimated

Age of onset

Infancy

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ICD-10

E76.2

Inheritance

Autosomal dominant A pathogenic variant in only one gene copy in each cell is sufficient to cause an autosomal dominant disease

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Autosomal recessive Pathogenic variants in both copies of each gene of the chromosome are needed to cause an autosomal recessive disease and observe the mutant phenotype

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X-linked
dominant X-linked dominant inheritance, sometimes referred to as X-linked dominance, is a mode of genetic inheritance by which a dominant gene is carried on the X chromosome.

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X-linked
recessive Pathogenic variants in both copies of a gene on the X chromosome cause an X-linked recessive disorder

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Mitochondrial or multigenic Mitochondrial genetic disorders can be caused by changes (mutations) in either the mitochondrial DNA or nuclear DNA that lead to dysfunction of the mitochondria and inadequate production of energy.

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Multigenic or multifactor Inheritance involving many factors, of which at least one is genetic but none is of overwhelming importance, as in the causation of a disease by multiple genetic and environmental factors.

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Not applicable

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Other names (AKA)

Mucopoly-saccharidosis type 3B; Sanfilippo syndrome B; N-acetyl-alpha-d-glucosaminidase deficiency;

Categories

Congenital and Genetic Diseases; Eye diseases; Metabolic disorders;

Summary

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]

Symptoms

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.

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

Diagnosis

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.

    Organizations

    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).

        Learn more

        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.

            References

            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; https://www.nlm.nih.gov/medlineplus/ency/article/001210.htm. Accessed 7/2/2015.