The clinical and electrophysiological phenotype in 42 patients with Charcot-Marie-Tooth disease type 1A (CMT1A) were analysed at Wayne State University, Detroit, MI. Muscle weakness, and reduced amplitudes and motor unit number estimates of compound motor nerve action potentials (CMAPs) correlated with clinical disability, while slowed nerve conduction velocities (NCVs) did not. Loss of joint position sense and reduction in amplitude of sensory nerve action potentials (SNAPs) also correlated with disability, while sensory NCVs did not. Neurological dysfunction and disability in CMT1A are correlated with loss or degeneration of large motor and sensory axons. 
COMMENT. The clinical neurologic examination, EMG and NCS may be used to measure the degenerative process affecting axons in peripheral nerves in CMT1A, and any benefits from novel therapies to promote axonal regeneration in the future.