A neonatal polyvisceral failure linked to a de novo homoplasmic mutation in the mitochondrially encoded cytochrome b gene

Mitochondrion. 2009 Sep;9(5):346-52. doi: 10.1016/j.mito.2009.06.002. Epub 2009 Jun 27.


Mutations within the mitochondrially encoded cytochrome b (MTCYB) gene are heteroplasmic and lead to severe exercise intolerance. We describe an unusual clinical presentation secondary to a novel homoplasmic mutation within MTCYB. The m.15635T>C transition (S297P) was carried by a newborn who presented with a polyvisceral failure. This mutation was responsible for a complex III deficiency. It was homoplasmic in all tissues tested and was undetectable in patient's mother. Functional analyses, including studies on patient's cybrid cell lines, demonstrate the pathogenicity of this variant. Our data show that mutations within MTCYB can be responsible for severe phenotype at birth.

Publication types

  • Case Reports
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Child
  • Cytochromes b / deficiency*
  • Cytochromes b / genetics*
  • DNA, Mitochondrial / genetics*
  • Humans
  • Infant, Newborn
  • Male
  • Mitochondrial Diseases / genetics*
  • Multiple Organ Failure / genetics*
  • Mutation, Missense*
  • Point Mutation*
  • Young Adult


  • DNA, Mitochondrial
  • Cytochromes b