Charcot-Marie-Tooth disease: Difference between revisions

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'''For patient information, click [[Charcot-Marie-Tooth disease (patient information)|here]]'''
{{Charcot-Marie-Tooth disease}}
{{Charcot-Marie-Tooth disease}}
{{CMG}}
{{CMG}}


{{SK}} Hereditary motor and sensory neuropathy; peroneal muscular atrophy
{{SK}} Hereditary motor and sensory neuropathy; peroneal muscular atrophy
==[[Charcot-Marie-Tooth disease overview|Overview]]==
==[[Charcot-Marie-Tooth disease overview|Overview]]==


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==[[Charcot-Marie-Tooth disease pathophysiology|Pathophysiology]]==
==[[Charcot-Marie-Tooth disease pathophysiology|Pathophysiology]]==


==[[Charcot-Marie-Tooth disease epidemiology and demographics|Epidemiology and Demographics]]==
==[[Charcot-Marie-Tooth disease causes|Causes]]==


==Description==
==[[Charcot-Marie-Tooth disease differential diagnosis|Differentiating Charcot-Marie-Tooth disease from other Diseases]]==
The disorder is caused by the absence of molecules that are essential for normal function of the nerves due to errors in the genes coding these molecules. The absence of these chemical substances gives rise to dysfunction either in the [[axon]] or the [[myelin]] sheath of the nerve cell. Most of the mutations identified result in disrupted myelin production, however the most common mutations occur in gene MFN2, which doesn't seem to have anything to do with myelin. Instead MFN2 controls behaviour of mitochondria. Recent research showed that the mutated MFN2 causes mitochondria to form large clusters. In nerve cells these large clusters of mitochondria failed to travel down the axon towards the synapses. It is suggested these mitochondria clots make the synapses fail, resulting in CMT disease.<ref name="Baloh">Baloh, R., Schmidt, R., Pestronk, A. and Milbrandt, J. (2007) The Journal of Neuroscience 27(2):422-430, http://www.jneurosci.org/cgi/content/abstract/27/2/422 accessed 070122</ref>


The different classes of this disorder have been divided into the primary demyelinating neuropathies (CMT1, CMT3, and CMT4) and the primary axonal neuropathies (CMT2).  Recent studies, however, show that the pathologies of these two classes are frequently intermingled, due to the dependence and close cellular interaction of [[Schwann cell]]s and neurons.  Schwann cells are responsible for myelin formation, enwrapping neural axons with their plasma membranes in a process called “myelination”.<ref name="Berger">Berger, P., Young, P. and U. Suter (2002) Neurogenetics 4:1-15. http://www.springerlink.com/, accessed 060220</ref>
==[[Charcot-Marie-Tooth disease epidemiology and demographics|Epidemiology and Demographics]]==


The molecular structure of the nerve depends upon the interactions between neurons, Schwann cells, and [[fibroblast]]s.  Schwann cells and neurons, in particular, exchange signals that regulate survival and differentiation during development.  These signals are important to CMT disease because a disturbed communication between Schwann cells and neurons, resulting from a genetic defect, is observed in this disorder.<ref name="Berger">Berger, P., Young, P. and U. Suter (2002) Neurogenetics 4:1-15. http://www.springerlink.com/, accessed 060220</ref>
==[[Charcot-Marie-Tooth disease natural history, complications and prognosis|Natural History, Complications and Prognosis]]==


It is clear that interaction with demyelinating Schwann cells causes the expression of abnormal axonal structure and function, but we still do not know how these abnormalities result in CMT.  One possibility is that the weakness and sensory loss experienced by patients with CMT is a result of axonal degradation.  Another possibility is that axonal dysfunction occurs, not degeneration, and that this dysfunction is induced by demyelinating Schwann cells.<ref name="Krajewski">Krajewski, K.M., Lewis, R.A., Fuerst, D.R., Turansky, C., Hinderer, S.R., Gerbern, J., Kamholz, J. and M.E. Shy (2000) Brain 123:1516-1527 [http://brain.oxfordjournals.org/cgi/content/full/123/7/1516#SEC4, accessed 060220]</ref> 
==Diagnosis==


Most patients experience demyelinating neuropathies, and this is characterized by a reduction in nerve conduction velocity (NCV), due to a partial or complete loss of the myelin sheath.  Axonopathies, on the other hand, are characterized by a reduced compound muscle action potential (CMAP), while NCV is normal or only slightly reduced.<ref name="Berger">Berger, P., Young, P. and U. Suter (2002) Neurogenetics 4:1-15. http://www.springerlink.com/, accessed 060220</ref>
[[Charcot-Marie-Tooth disease history and symptoms|History and Symptoms]] | [[Charcot-Marie-Tooth disease physical examination|Physical Examination]] | [[Charcot-Marie-Tooth disease laboratory findings|Laboratory Findings]] | [[Charcot-Marie-Tooth disease other diagnostic studies|Other Diagnostic Studies]]


==Diagnosis==
==Treatment==
The diagnosis is established by [[electromyography]] examination (which shows that the velocity of nerve impulse conduction is decreased and the time required to charge the nerve is increased) and nerve [[biopsy]].  [[Genetic marker]]s have been identified for some, but not all forms of the disease.


==Genetic testing==
[[Charcot-Marie-Tooth disease medical therapy|Medical Therapy]] | [[Charcot-Marie-Tooth disease surgery|Surgery]] | [[Charcot-Marie-Tooth disease primary prevention|Primary Prevention]] | [[Charcot-Marie-Tooth disease cost-effectiveness of therapy|Cost-Effectiveness of Therapy]] | [[Charcot-Marie-Tooth disease future or investigational therapies|Future or Investigational Therapies]]
Genetic testing is available for many of the different types of Charcot-Marie-Tooth.  For a listing of test availabilities, see [http://www.genetests.org GeneTests.org]


==External links==
==External links==
* {{DMOZ|Health/Conditions_and_Diseases/Neurological_Disorders/Peripheral_Nervous_System/Charcot-Marie-Tooth_Disease/}}
* {{DMOZ|Health/Conditions_and_Diseases/Neurological_Disorders/Peripheral_Nervous_System/Charcot-Marie-Tooth_Disease/}}
==References==
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{{Muscular Dystrophy}}
{{Muscular Dystrophy}}

Latest revision as of 18:52, 22 August 2012

Charcot-Marie-Tooth disease
The foot of a person with Charcot-Marie-Tooth. The lack of muscle, a high arch, and hammer toes are signs of the genetic disease.
ICD-10 G60.0
ICD-9 356.1
DiseasesDB 5815 Template:DiseasesDB2
MedlinePlus 000727
MeSH D002607

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]

Synonyms and keywords: Hereditary motor and sensory neuropathy; peroneal muscular atrophy

Overview

Historical Perspective

Classification

Pathophysiology

Causes

Differentiating Charcot-Marie-Tooth disease from other Diseases

Epidemiology and Demographics

Natural History, Complications and Prognosis

Diagnosis

History and Symptoms | Physical Examination | Laboratory Findings | Other Diagnostic Studies

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Medical Therapy | Surgery | Primary Prevention | Cost-Effectiveness of Therapy | Future or Investigational Therapies

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ca:Malaltia de Charcot-Marie-Tooth de:Morbus Charcot-Marie-Tooth it:Malattia di Charcot-Marie-Tooth nl:Hereditaire Motorische en Sensorische Neuropathieën no:Charcot-Marie-Tooths sykdom sv:Charcot-Marie-Tooths sjukdom

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