Mitochondrial myopathy and ophthalmoplegia in a sporadic patient with the 5698G→A mitochondrial DNA mutation

We describe a second patient carrying the 5698G→A transition in the mitochondrial DNA gene encoding tRNA Asn, who has an apparently isolated mitochondrial myopathy with chronic progressive external ophthalmoplegia. A muscle biopsy showed the presence of ragged-red and COX-negative fibres. Analysis of the mutation load on single muscle fibres showed significant segregation of the 5698G→A with COX-depleted fibres. These results indicate that the 5698G→A is pathogenic. © 2004 Elsevier B.V. All rights reserved.