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 2P


Other Names:
CMT2P; Charcot-Marie-Toothe disease, axonal, type 2P ; CHARCOT-MARIE-TOOTH NEUROPATHY, TYPE 2P
Categories:
Charcot-Marie-Tooth disease type 2P (CMT2P) is a subtype of Charcot-Marie-Tooth caused by changes (mutations) in the LRSAM1 gene. The onset of symptoms commonly occurs between 20 and 40 years of age and the disease seems to be relatively mild and benign. Symptoms may include mild loss of sensation in the fingertips and severe loss of sensation in the feet and legs. The most common type of sensation loss is to vibration, but proprioception (the sense of how we are oriented in space) and perception to pain may also be affected. Individuals with CMT2P may also have muscle twitches (fasciculations) and cramps (in younger patients) and muscular weakness and muscular wasting in the legs, feet and hands (in older individuals). It may be inherited in an autossomal dominant or autossomal recessive pattern.[1][2]
Last updated: 6/26/2015
The onset of symptoms in the reported cases is between 20 to 40 years of age and the disease seems to be relatively mild and benign. Affected individuals may have the following signs and symptoms:[1][2]

• Mild loss of sensation on fingertips and severe loss of sensation in feet and legs, most markedly to vibration but also involving proprioception (the sense of how we are oriented in the space) and pain perception.
• Muscle twitches (fasciculations) and cramps in younger patients.
• Muscular weakness in legs and hands in older individuals.
• Wasting of muscles of the hand and legs and feet.
• Absent reflexes.
• Motor nerve conduction studies are usually normal.
• Needle EMG may show giant motor units potentials (MPU) both in proximal and distal muscles of all patients. The motor unit is a part of the neuromuscular system that contains a cell, its axon, and all of the muscle fibers that it innervates, including the axon's specialized point of connection to the muscle fiber, the neuromuscular junction. In routine needle-electrode examination (electromyography (EMG) of voluntary muscle contraction, the consultant assesses the electrical signal generated by the MUs, termed the "MU action potential" (or MUAP). Needle EMG findings suggestive of denervation include giant MUP.
Last updated: 6/26/2015

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
5%-29% of people have these symptoms
Hammertoe
Hammer toe
Hammertoes
[ more ] 		0001765
Percent of people who have these symptoms is not available through HPO
Areflexia
Absent tendon reflexes
0001284
Autosomal dominant inheritance 0000006
Axonal degeneration 0040078
Axonal degeneration/regeneration 0003378
Decreased motor nerve conduction velocity 0003431
Distal amyotrophy
Distal muscle wasting
0003693
Distal muscle weakness
Weakness of outermost muscles
0002460
Distal sensory impairment
Decreased sensation in extremities
0002936
Fasciculations
Muscle twitch
0002380
Foot dorsiflexor weakness
Foot drop
0009027
Hyporeflexia
Decreased reflex response
Decreased reflexes
[ more ] 		0001265
Impaired distal vibration sensation 0006886
Incomplete penetrance 0003829
Peripheral axonal degeneration 0000764
Pes cavus
High-arched foot
0001761
Slow progression
Signs and symptoms worsen slowly with time
0003677
Steppage gait
High stepping
0003376
Toe walking
Toe-walking
0040083
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Last updated: 7/1/2020

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

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

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.

In-Depth Information

  • 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.

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  1. Engeholm M & cols. A novel mutation in LRSAM1 causes axonal Charcot-Marie-Tooth disease with dominant Inheritance. BMC Neurology. June 3, 2014; 14:118. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4060843/. Accessed 6/26/2015.
  2. Charcot-Marie-Toothe disease, axonal, type 2P. OMIM. February 24, 2015; http://omim.org/entry/614436. Accessed 6/26/2015.