This girl was evaluated for the first time at age 2.5 years because of an unsteady gait of 6 months' duration. The birth history was unremarkable, and she had developed normally for the first 2 years of her life. Examination of the patient at that time was remarkable for short stature, hypertrichosis of the back and proximal extremities, kyphoscoliosis, generalized hyporeflexia, intention tremor of the arms, and wide-based gait. The following laboratory data were normal: complete blood count (CBC), urinalysis, electrolytes, blood urea nitrogen (BUN), sugar, calcium, thyroid studies, serum immunoglobulin A, 0800 h plasma cortisol, leukocyte lysosomal enzymes, urinary amino acids, and urine phytanic acid. Cerebrospinal fluid (CSF) showed an increased protein concentration of 115 mg/dl. An electromyogram (EMG) showed fibrillations and sharp waves diffusely in all muscles tested, which were interpreted as being consistent with denervation.Nerve conduction velocities (NCVs) of the right common peroneal nerve was 34 m/s, the right posterior tibial nerve NCV was 23.6 d s , the right median nerve NCV was 26.3 d s , and the right ulnar nerve NCV was 35.9 d s . A sural nerve biopsy showed many thinly myelinated fibers with some active segmental demyelination, mild hypertrophic interstitial neuropathy, and marked endoneurial fibrosis ( Figs. 1 and 2).A videotape segment accompanies this article.