Deletions of mitochondrial DNA in Kearns-Sayre syndrome and ocular myopathies: genetic, biochemical and morphological studies

J Neurol Sci. 1991 Feb;101(2):168-77. doi: 10.1016/0022-510x(91)90042-6.


Genetic, biochemical and morphological investigations were conducted on skeletal muscle mitochondria from 6 cases of ocular myopathy: 4 cases with Kearns-Sayre syndrome (KSS) and 2 with chronic progressive external ophthalmoplegia. All of these 6 cases showed mitochondrial DNA (mtDNA) deletions in addition to normal sized DNA in the quadriceps muscle. The deletions ranging from 3 to 8 kbp were also mapped between nucleotides 5500 and 16000 by Southern blot. The deleted genes encoded for some subunits of complexes I, IV, V and 5-10 tRNAS. The boundaries of the deletions have been sequenced in three patients. Five patients had mitochondrial respiratory chain deficiency in complex I as shown by the low oxygen consumption in isolated mitochondria using three NAD(+)-linked substrates. Mitochondria with an abnormal ultrastructure were also observed in 2 cases. A good relationship between the cytochrome c oxidase deficiency and the amount of deleted mtDNA was shown in our present investigations.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Base Sequence
  • Blotting, Southern
  • Chromosome Deletion*
  • Cytochrome-c Oxidase Deficiency
  • DNA Mutational Analysis
  • DNA, Mitochondrial / genetics*
  • Electron Transport / genetics*
  • Electron Transport Complex IV / genetics
  • Female
  • Humans
  • Kearns-Sayre Syndrome / genetics
  • Kearns-Sayre Syndrome / pathology
  • Male
  • Middle Aged
  • Mitochondria, Muscle / metabolism
  • Mitochondria, Muscle / ultrastructure
  • Molecular Sequence Data
  • Multienzyme Complexes / deficiency
  • Multienzyme Complexes / genetics*
  • Muscles / pathology
  • Ophthalmoplegia / genetics*
  • Ophthalmoplegia / pathology
  • Oxygen Consumption
  • Polymerase Chain Reaction
  • RNA, Transfer / genetics


  • DNA, Mitochondrial
  • Multienzyme Complexes
  • RNA, Transfer
  • Electron Transport Complex IV