We studied a 33-year-old woman with a negative family history. Both of her parents were examined clinically by nerve conduction velocities (NCVs) and EMG, with normal results. The clinical onset of her condition was at 24 months, with severe weakness and atrophy of her feet and hands, but the proximal muscles were relatively spared. She had bilateral pes cavus, distal weakness and hypesthesia for touch and proprioception, areflexia, claw hands, and severe thoracolumbar kyphoscoliosis. NCVs showed absent motor and sensory responses and EMG revealed diffuse fibrillation potentials. Molecular genetic studies indicated a de novo dominant missense point mutation of exon 3 of the peripheral myelin protein 22 gene at nucleotide 264 that caused the replacement of serine with leucine.