Charcot-Marie-Tooth disease classification
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- CMT Type 1 (CMT1): Type 1 affects approximately 80% of CMT patients and is the most common type of CMT. The subtypes share clinical symptoms. Autosomal dominant. Causes demyelination, which can be detected by measuring nerve conduction velocities.
- CMT Type 2 (CMT2): Type 2 affects approximately 20-40% of CMT patients. Type 2 CMT is Autosomal dominant neuropathy with its main effect on the axon. The average nerve conduction velocity is slightly below normal, but generally above 38 m/s
- CMT Type 3 (CMT3): Type 3 affects a very few CMT patients.
- CMT Type 4 (CMT4): Type 4 affects a very few CMT patients.
- CMT X-Linked (CMTX): CMTX affects approximately 10-20% of CMT patients and is X-linked dominant. Approx 10% of X-linked CMT patients have some other form than CMTX.
More details on the types are provided in the table below:
|CMT1A||118220||PMP22||17p11.2||The most common form of the disease, 70-80% of Type 1 patients. Average NCV: 15-20 m/s when associated with essential tremor and ataxia, called Roussy-Levy Syndrome|
|CMT1B||118200||MPZ||1q22||Caused by mutations in the gene producing protein zero (P0). 5-10% of Type 1 patients. Average NCV: <20 m/s|
|CMT1C||LITAF||16p13.1-p12.3||Causes severe demyelination, which can be detected by measuring nerve conduction velocities. Autosomal dominant. Usually shows up in infancy. Average NCV: 26-42 m/s. Identical symptoms to CMT-1A.|
|CMD1D||EGR2||10q21.1-q22.1||Average NCV: 15-20 m/s|
|CMT2A||118210||MFN2 or KIF1B||1p36||The cause is likely located on chromosome 1 for the mitofusion 2 protein. Some research has also linked this form of CMT to the protein kinesin 1B. Does not show up on nerve conduction velocity tests, because it is caused by axonopathy.|
|CMT2B||600882||RAB7 (RAB7A, RAB7B)||3q21.|
|CMT2B1||LMNA||1q22||Autosomal recessive axonal CMT, (laminopathy)|
|CMT2C||606071||12q23-q24||May cause vocal cord, diaphragm, and distal weaknesses.|
|CMT2D||601472||GARS||7p15||Patients with mutations in the GARS gene tend to have more severe symptoms in the upper extremities (hands), which is atypical for CMT in general.|
|CMT3||145900||varies||varies||Sometimes called Dejerine-Sottas disease. Rarely found. Autosomal recessive. Average NCV: Normal (50-60m/s)|
|CMT4B2||CMT4B2 (SBF2)||11p15||May be called "SBF2/MTMR13". Autosomal recessive.|
|CMT4C||KIAA1985 (SH3TC2)||5q32||May lead to respiratory compromise.|
|CMT4D||601455||NDRG1||8q24.3||Autosomal recessive, demyelinating, deafness|
|CMT1E||118300||PMP22||17p11.2||Autosomal dominant, demyelinating, deafness|
|CMT4E||EGR2||10q21.1-10q22.1||"CMT4E" is a tentative name|
|CMT4F||PRX||19q13.1-19q13.2||"CMT4F" is a tentative name|
|CMT4J||611228||KIAA0274 (FIG4)||6q21||Autosomal recessive|
|CMTX1||302800||GJB1||Xq13.1||Average NCV: 25-40 m/s|
|CMT||118301||with Ptosis and Parkinsonism|
|CMT||302803||type 1 aplasia cutis congenita|