Charcot-Marie-Tooth disease- Type 2H
Overview
Charcot-Marie-Tooth disease, Type 2H: 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 2H has an autosomal recessive inheritance and involves a defect in the GDAP1 gene on chromosome 8.
Symptoms
* Muscle weakness in extremities * Muscle wasting in extremities * Foot deformity * Sensory lost in extremities * Abnormal gait
Causes
The disorder is caused by the absence of molecules that are essential for normal function of the nerves due to deficiencies in the structure of 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. Symptoms usually begin in late-childhood or early adulthood. Usually, the initial symptom is foot drop due to involvement of the peroneal nerve, which is responsible for raising the feet,early in the course of the disease.
Diagnosis
A definitive diagnosis for a specific type of CMT is established via genetic testing for most types. However, some genetic markers have not yet been identified, and a diagnosis can also be established via an 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.