Studies on mitochondrial pathogenesis of Rett syndrome: ultrastructural data from skin and muscle biopsies and mutational analysis at mtDNA nucleotides 10463 and 2835

In order to verify the pathogenic role of mitochondria in Rett syndrome, th e results are reported of skin and muscle biopsies in two RS patients, show ing morphological ultrastructural abnormalities in mitochondrial number and size. The investigation on two recently described mtDNA mutations (at nt 1 0463 and 2835) (Lewis et al., 1995; Tang et al., 1997) gave contrasting res ults with respect to previously reported data. In particular, the first mut ation has been found in seven subjects, five of whom were from two differen t control groups, while the second mutation has been not detected in any of the 26 patients and controls. Although these results present some signs of a morphological impairment of mitochondria, they do not support the hypoth esis that the two mutations may have a primary role in the pathogenesis of the syndrome and indicate the need for further investigations on the role o f mtDNA in the pathogenesis of the syndrome.