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Disease Profile

Charcot-Marie-Tooth disease type 2B

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.

Unknown

Age of onset

Adolescent

ICD-10

G60.0

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.

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)

CMT 2B; Charcot-Marie-Tooth disease, axonal, Type 2B; Charcot-Marie-Tooth disease, neuronal, Type 2B;

Categories

Congenital and Genetic Diseases; Nervous System Diseases

Summary

Charcot-Marie-Tooth disease type 2B (CMT2B) is an inherited peripheral neuropathy with onset in the second or third decade of life. Common signs and symptoms include severe loss of sensation in the feet, lower legs, hands, and forearms; reduced tendon reflexes in the ankles; weakness in the lower limbs; and the loss of muscle tissue (muscle atrophy). This type of CMT is also associated with the formation of ulcers in the hands and feet. CMT2B is caused by changes in the RAB7A gene. It is inherited in an autosomal dominant fashion.[1][2][3] Treatment is aimed at addressing the symptoms in each patient and often involves a team of specialists.[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
Areflexia
Absent tendon reflexes
0001284
Autoamputation of foot
0001868
Autosomal dominant inheritance
0000006
Axonal degeneration/regeneration
0003378
Decreased motor nerve conduction velocity
0003431
Decreased number of peripheral myelinated nerve fibers
0003380
Distal amyotrophy
Distal muscle wasting
0003693
Dystrophic toenail
Poor toenail formation
0001810
Foot dorsiflexor weakness
Foot drop
0009027
Foot osteomyelitis
Foot bone infection
0001886
Hammertoe
Hammer toe
Hammertoes

[ more ]

0001765
Hyporeflexia
Decreased reflex response
Decreased reflexes

[ more ]

0001265
Peripheral axonal atrophy
0003384
Pes cavus
High-arched foot
0001761
Pes planus
Flat feet
Flat foot

[ more ]

0001763
Sensory impairment
0003474
Sensory neuropathy
Damage to nerves that sense feeling
0000763
Steppage gait
High stepping
0003376

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.

    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

      Organizations Providing General Support

        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

        • The Muscular Dystrophy Association has developed an information page entitled "Surgery Sometimes, Bracing Often, Caution Always: Caring for the CMT-affected Foot." Click on Muscular Dystrophy Association to view this information page.

          In-Depth Information

          • GeneReviews provides current, expert-authored, peer-reviewed, full-text articles describing the application of genetic testing to the diagnosis, management, and genetic counseling of patients with specific inherited conditions.
          • 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 Charcot-Marie-Tooth disease type 2B. Click on the link to view a sample search on this topic.

            References

            1. Bird TD. Charcot-Marie-Tooth Neuropathy Type 2. GeneReviews. April 14, 2016; https://www.ncbi.nlm.nih.gov/books/NBK1285/.
            2. Bucci C, De Luca M. Molecular basis of Charcot-Marie-Tooth type 2B disease. Biochem Soc Trans. 2012 Dec 1; 40(6):1368-72. https://www.ncbi.nlm.nih.gov/pubmed/23176482.
            3. Olga Y. Ponomareva, Kevin W. Eliceiri, and Mary C. Halloran. Charcot-Marie-Tooth 2b associated Rab7 mutations cause axon growth and guidance defects during vertebrate sensory neuron development. Neural Dev. 2016 Jan 20; 11:2. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4721196/.