Multisystem disorder associated with a missense mutation in the mitochondrial cytochrome b gene

Ann Neurol. 2001 Oct;50(4):540-3. doi: 10.1002/ana.1224.


Mitochondrial cytochrome b mutations have been reported to have a homogenous phenotype of pure exercise intolerance. We describe a novel mutation in the cytochrome b gene of mitochondrial DNA (A15579G) associated with a selective decrease of muscle complex III activity in a patient who, besides severe exercise intolerance, also has multisystem manifestations (deafness, mental retardation, retinitis pigmentosa, cataract, growth retardation, epilepsy). The point mutation is heteroplasmic in muscle (88%) and leukocytes (15%), and changes a highly conserved tyrosine to cysteine at amino acid position 278.

Publication types

  • Case Reports

MeSH terms

  • Adult
  • Cytochrome b Group / genetics*
  • DNA, Mitochondrial / genetics
  • Epilepsy / genetics
  • Female
  • Hearing Loss, Bilateral / genetics*
  • Humans
  • Intellectual Disability / genetics*
  • Muscular Diseases / genetics*
  • Mutation, Missense*
  • Phenotype
  • Polymorphism, Restriction Fragment Length
  • Retinitis Pigmentosa / genetics


  • Cytochrome b Group
  • DNA, Mitochondrial