Review Question - QID 3222

Charcot-Marie-Tooth disease is a sensory motor demyelinating neuropathy that is autosomal dominant and is often due to a mutation of PMP22 (peripheral myelin protein 22) located at Chromosome 17p12. Orthopaedic manifestations include progressive distal muscle wasting/weakness (especially peroneal muscles), areflexia, hammertoes, hip dysplasia, and cavovarus foot deformities. Low nerve conduction velocities with prolonged distal latencies are noted in the peroneal, ulnar, and median nerves. Nerve pathology can show simultaneous demyelinization and remyelinization. There are several subtypes of the disease, but diagnosis is made commonly by DNA testing for a duplication of a portion of chromosome 17. Other pediatric congenital disorders and their associated genetic defect include Duchenne's/Becker's muscular dystrophies (dystrophin), Limb-girdle dystrophies (sarcoglycan and dystroglycan complex), myotonic dystrophy (myotonin), and spinal muscular atrophy (Survival motor neuron protein).