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Genetic and Rare Diseases Information Center (GARD)

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Charcot-Marie-Tooth disease type 2B

Other Names for this Disease
  • Charcot Marie Tooth disease type 2B
  • Charcot-Marie-Tooth disease, axonal, Type 2B
  • Charcot-Marie-Tooth disease, neuronal, Type 2B
  • CMT 2B
  • Hereditary motor and sensory neuropathy 2 B (HMSN 2 B)
More Names
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Your Question

Why is it that I can never find any information about CMT 2B.  Is there no research being done on this type?  Is it the rarest kind?   I have it and can find nothing about it.  I am wheelchair bound, cannot walk at all, have urinary problems and bowel problems, breathing problems, weakness in arms also. Many of my family members also have CMT 2B.

Our Answer

We have identified the following information that we hope you find helpful. If you still have questions, please contact us.

What is Charcot-Marie-Tooth type 2B?

Charcot-Marie-Tooth disease type 2B (CMT2B) affects the peripheral nerves, the nerves running from outside the brain and spine. Common signs and symptoms include slowly progressive weakness and numbness in the feet, lower leg muscles, hands, and forearms. This type of CMT is also associated with the formation of ulcers in the hands and feet. Symptoms may start in childhood to early adulthood, although later onset (>50 years) has also been described. Symptoms of CMT2B vary but tend to be similar to that of CMT type 1. CMT2B is caused by changes in the RAB7A gene. It is inherited in an autosomal dominant fashion.[1]
Last updated: 9/9/2013

Are there any research studies investigating Charcot-Marie-Tooth type 2B?

Yes. The Inherited Neuropathies Consortium is a team of doctors, nurses, research coordinators, and research labs throughout the U.S., working together to improve the lives of people with all types of Charcot Marie Tooth disease through research. The Inherited Neuropathies Consortium has a registry for patients who wish to be contacted about clinical research opportunities.

For more information on the registry see:
Last updated: 9/10/2013

How rare is Charcot-Marie-Tooth type 2B?

Unfortunately for the rare diseases, there's often not a calculated incidence or prevalence.  There is no official method for tracking these conditions, only estimates. Studies suggest that around 20-30% of people with Charcot Marie Tooth disease have type 2. In only around 20-30% of cases of CMT type 2 is the underlying genetic defect identified. Most of these cases are due to a mutation in the MFN2 or GJB1 genes. CMT type 2 due to mutations in the RAB7A gene (type 2B disease) is very rare.[2] Fewer than 10 families with CMT2B have been described in the medical literature.
Last updated: 9/9/2013

  • Bird TD. Charcot-Marie-Tooth Neuropathy Type 2. GeneReviews. September 24, 1998; Accessed 9/9/2013.
  • Murphy SM, Laura M, Fawcett K, Pandraud A, Liu YT, Davidson GL, Rossor AM, Polke JM, Castleman V, Manji H, Lunn MP, Bull K, Ramdharry G, Davis M, Blake JC, Houlden H, Reilly MM. Charcot-Marie-Tooth disease: frequency of genetic subtypes and guidelines for genetic testing. J Neurol Neurosurg Psychiatry. 2012 Jul;83(7):706-10; Accessed 9/9/2013.