Muscle involvement in a case of oculocutaneous albinism

A 2-month-old girl with tyrosinase-positive oculocutaneous albinism (OCA) and severe muscle hypotonia is reported. She was admitted to our hospital because of poor sucking and poor weight gain. On physical examination she was found to have generalized muscle weakness and multiple anomalies including deafness, mental retardation, cataracta and a high-arched palate. A muscle biopsy showed marked variation in fiber size with bimodal distribution, suggesting a neuropathic process. Since electromyography showed a myopathic pattern, CK was definitely elevated and muscle histologic examination did not show any denervation of the type found in Werdnig-Hoffmann disease, the present disorder was assumed to be caused either by hardly developed motoneurons or by abnormal interaction between muscles and nerves.