It is caused by a mutation of the genes that code for proteins necessary for the functioning of the myelin sheath affecting the conductance of nerve signals and resulting in loss of muscles' ability to move.

Neurological damage may result in absent tendon reflexes (areflexia), some distal sensory loss and decreased excitability of muscles to galvanic and faradic stimulation.

[1] These symptoms frequently translate into delayed onset of ability to walk, loss of coordination and balance, foot drop, and foot-bone deformities.

[4] In common with other types of Charcot–Marie–Tooth disease, examination reveals decreased nerve conduction velocity and histologic features of a hypertrophic demyelinating neuropathy.

[citation needed] While the clinical picture may point towards the diagnosis of the Roussy–Lévy syndrome, the condition can only be confirmed with absolute certainty by carrying out KT or MRT.