Novel MTCYB mutation in a young patient with recurrent stroke-like episodes and status epilepticus

Am J Med Genet A. 2014 Nov;164A(11):2922-5. doi: 10.1002/ajmg.a.36725. Epub 2014 Aug 14.


The acronym "MELAS" (mitochondrial encephalomyopathy with lactic acidosis and stroke-like episodes) denotes patients with histological, biochemical and/or molecular evidence of mitochondrial disease who experience stroke-like episodes. Here we report on a girl with repeated stroke-like episodes and status epilepticus, who was diagnosed with MELAS due to a novel mitochondrial cytochrome b gene (MTCYB) mutation (m.15092G>A, which predicts p.G116S). Western blotting and in silico analyses suggested that this mutation could affect the stability of complex III. Cytochrome b is the only mtDNA-encoded subunit of respiratory chain complex III. Mutations in MTCYB have been associated with isolated mitochondrial myopathy and exercise intolerance, and rarely with multisystem and/or central nervous system involvement. If the m.3243A>G and other common MELAS mutations are absent in several tissues, MTCYB should be sequenced from muscle in patients with stroke-like episodes, especially if muscle histology does not support a mitochondrial myopathy and lactic acidosis is absent.

Keywords: cytochrome b; genetics MELAS; mitochondrial encephalomyopathy with lactic acidosis and stroke-like episodes; mtDNA; stroke.

Publication types

  • Case Reports

MeSH terms

  • Adult
  • Amino Acid Sequence
  • Brain / pathology
  • Cytochromes b / chemistry
  • Cytochromes b / genetics*
  • Female
  • Genetic Association Studies
  • Humans
  • Magnetic Resonance Imaging
  • Molecular Sequence Data
  • Mutation*
  • Phenotype*
  • Polymorphism, Genetic
  • Sequence Alignment
  • Status Epilepticus / diagnosis*
  • Status Epilepticus / genetics*
  • Young Adult


  • Cytochromes b