Clinical features of mitochondrial myopathy.

Five patients with mitochondrial myopathy are discussed. Two presented with progressive external ophthalmoplegia (CPEO), one with CPEO and retinitis pigmentosa, and two with Kearns-Sayre syndrome. Ragged red fibres and intra-mitochondrial paracrystalline inclusions were found in each case. The clinical heterogeneity of the mitochondrial myopathy syndrome in the presence of identical pathological changes in skeletal muscle is emphasised.