Renal and skin involvement in a patient with complete Kearns-Sayre syndrome

We report on a 13-year-old girl with complete Kearns-Sayre syndrome (KSS) and unusual manifestations of anhidrosis and de Toni-Fanconi-Debré syndrome which preceded by several years the onset of KSS triad. Histochemical examination of skeletal muscle showed focal deficiency of cytochrome c oxidase (CCO). Southern blot analysis of mitochondrial DNA (mtDNA) demonstrated a deletion of 5.4 kb in 60% of the total mtDNAs isolated from the muscle and kidney. On electron microscopy, epithelial cells of the proximal and distal renal tubules and the sweat glands showed an increased number of giant mitochondria with complicated and concentric cristae. This appears to be the first report of complete KSS associated with renal and skin involvement. Data obtained in this patient provide important information on the clinical heterogeneity and tissue specificity of CCO deficiency.