Ultrastructural and biochemical alterations of muscle mitochondria are reported in two girls, aged 4 years, with Rett syndrome examined at the Institute of Neurological Sciences, University of Siena, Italy. Mitochondria were abnormally swollen and dumb-bell-shaped, and cytochrome c oxidase and NADH cytochrome c reductase were decreased in activity. The primary or secondary role of this mitochondrial pathology in the pathogenesis of the syndrome is undetermined. [1]
COMMENT. In contrast to the above, phosphorus magnetic resonance spectroscopy, proton MRS, muscle biopsies, and determination of pyruvate and lactate in plasma of 5 girls with Rett syndrome, examined at the John F Kennedy Institute, Glostrup, Denmark, failed to detect evidence for a mitochondrial disorder. [2]