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

Charcot-Marie-Tooth disease type 2B

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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.

The following information may help to address your question:


What is Charcot-Marie-Tooth type 2B?

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]
Last updated: 3/15/2017

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: http://rarediseasesnetwork.epi.usf.edu/INC/register/index.htm
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.[4] Fewer than 10 families with CMT2B have been described in the medical literature.
Last updated: 9/9/2013

We hope this information is helpful. We strongly recommend you discuss this information with your doctor. If you still have questions, please contact us.

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GARD Information Specialist

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  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/.
  4. 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; http://www.ncbi.nlm.nih.gov/pubmed/22577229. Accessed 9/9/2013.