Charcot-Marie-Tooth disease, Type 4A: CMT is an inherited neurological disease characterized by the gradual degeneration of nerves which starts in the hands and feet and results in progressive numbness, muscle weakness and loss of function. Type 4A has an autosomal recessive inheritance and involves a defect in the GDAP 1 protein gene on chromosome 8. The recessive forms of CMT tend to be more severe than the dominant form and often involve hand and foot problems as well as additional systemic symptoms.
* Delayed developmental milestones * Delayed walking * Delayed sitting * Hoarse voice * Vocal cord paresis
Genetic tests, done by drawing blood, are available to test for many, but not all, of the common chromosomal defects causing CMT. A positive genetic test can provide definitive diagnosis and provide useful information for family planning. However, a negative result does not rule out CMT since some forms cannot yet be tested by DNA sampling. Currently, 18 types can be identified by DNA testing: 1A, 1B, 1C, 1D, 1E, 1F, 1X, 2A, 2E, 2I, 2J, 2K, 4A, 4E, 4F, HNPP, CHN, and DSN. Click here to view a booklet on genetic testing and CMT prepared by Athena Diagnostics.