CMT1 | CMT2 | CMTX | CMT3* | CMT4 | |
Characteristic nerve pathology | Demyelinating | Axonal | Demyelinating and axonal | Demyelinating | Demyelinating |
Typical mode of inheritance | AD | AD | X-linked | AD > AR | AR |
Frequency amongst CMT types | 50% | 15 to 30% | 10 to 15% | Uncommon | <10% |
Typical age of symptom onset | First or second decade | Second or third decade (sometimes later) | First or second decade | Infancy | First decade |
Characteristic features |
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Other common features | Gait ataxia/tremor (CMT1a) | Intellectual disability (CMTX2, CMTX4) Deafness and optic neuropathy (CMTX5) | Delayed motor development | Cranial neuropathies (CMT4B1, CMT4D) | |
Conduction velocities on nerve conduction studies¶ | Moderate slowing (>15 to ≤35 m/s) | Normal or slight slowing (>40 m/s) | Mild slowing (>35 to ≤45 m/s) | Severe slowing (≤15 m/s) or absent | Moderate slowing (>15 to ≤35 m/s) |
AD: autosomal dominant; AR: autosomal recessive; CMT: Charcot-Marie-Tooth.
* Includes Dejerine-Sottas syndrome and congenital hypomyelinating neuropathy.
¶ Nerve conduction velocity slowing in patients with neuropathies varies by type and severity of neuropathy as well as physiologic factors such as specific nerve tested, ambient temperature and patient age, height, sex, and body habitus. Refer to UpToDate content on nerve conduction studies for additional information.Do you want to add Medilib to your home screen?