Roussy–Lévy syndrome

Roussy–Lévy syndrome
Classification and external resources
Specialty	neurology
ICD-10	G60.0
ICD-9-CM	334.3
OMIM	180800
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Roussy–Lévy syndrome, also known as Roussy–Lévy hereditary areflexic dystasia, is a rare genetic disorder of humans that results in progressive muscle wasting. It is caused by mutations in the genes that code for proteins necessary for the functioning of the myelin sheath of the neurons, affecting the conductance of nerve signals and resulting in loss of muscles' ability to move.

The condition affects people from infants through adults and is inherited in an autosomal dominant manner. Currently, no cure is known for the disorder.

Symptoms of the Roussy–Lévy syndrome mainly stem from nerve damage and the resulting progressive muscle atrophy. Neurological damage may result in absent tendon reflexes (areflexia), some distal sensory loss and decreased excitability of muscles to galvanic and faradic stimulation. Progressive muscle wasting results in weakness of distal limb muscles (especially the peronei), gait ataxia, pes cavus, postural tremors and static tremor of the upper limbs, kyphoscoliosis, and foot deformity.

These symptoms frequently translate into delayed onset of ability to walk, loss of coordination and balance, foot drop, and foot-bone deformities. They are usually first observed during infancy or early childhood, and slowly progress until about age 30, at which point progression may stop in some individuals, or symptoms may continue to slowly progress.

The Roussy–Lévy syndrome has been associated with two genetic mutations: a duplication of the PMP22 gene that carries the instructions for producing the peripheral myelin protein 22, a critical component of the myelin sheath; and a missense mutation in the MPZ gene which codes for myelin protein zero, a major structural protein of peripheral myelin.

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