A sporadic form of hereditary neuropathy with liability to pressure palsies: clinical, electrodiagnostic, and molecular genetic findings.

We report a patient who had episodes of recurrent peripheral nerve pressure palsies. Electrodiagnostically, we found a clear decrease of nerve conduction velocity in affected and unaffected nerves. All the patient's relatives showed entirely normal clinical and electrodiagnostic findings. Histopathologically, there were extensive irregularities of the myelin sheaths with numerous tomaculous swellings. DNA analysis revealed a deletion for probes flanking the PMP-22 gene at the maternal chromosome 17 in our patient. His mother showed a normal gene dosage for all markers deleted in our patient, indicating a new mutation.