Atypical phenotype of Charcot-Marie-Tooth disease type 1A

Two sisters with a Charcot-Marie-Tooth disease type 1A (CMT1A) duplication, who had an unusual CMT1A clinical phenotype, are described. The 63-year-old proband presented with dysesthesia on the inner side of the right leg. Neurological examination revealed a localized sensory disturbance in the lower extremities and mild weakness in the feet and left hand. Her 61-year-old sister had experienced several episodes of acute paralysis, and neurological examination showed moderate, sensory-dominant polyneuropathy. A reduction of myelinated fibers with many onion-bulb formations were observed in the sural nerve of the proband, and electrophysiological studies showed reduced motor nerve conduction velocities in both sisters. To diagnose CMT1A, we developed a CMT1A duplication test based on detection of CMT1A-specific junction fragments using the long polymerase chain reaction (PCR) method. A 3.3-kb CMT1A-specific junction fragment was detected in both patients, and their neuropathy may therefore have been associated with CMT1A duplication. (C) 1999 John Wiley & Sons, Inc.