Abnormal mitochondria on a renal biopsy from a case of mitochondrial myopathy.

Mitochondrial myopathy (MM) is reported in a 5-year-old girl with short stature, hypotonia, ptosis, retinal pigmentation, and Fanconi's syndrome. A muscle biopsy showed the characteristic features of MM, and a renal biopsy revealed abnormal mitochondria in tubular cells that were similar to those seen in the muscle. This is the first report of such findings in association with MM.