Muscle Carnitine Deficiency

A 61-year-old woman had proximal muscle weakness since 38 years of age. Eventually, her distal muscles became affected and she showed widespread muscle wasting, absent tendon reflexes, and electromyographic findings of a neuropathy. On biopsy, there was a lipid storage myopathy, lipid-containing vacuoles in leukocytes, and vacuoles in Schwann cells. The muscle carnitine level was abnormally low, but the serum carnitine level was normal. The findings are consistent with a generalized disorder of carnitine metabolism that may involve carnitine transport across cell membranes.