Mutations in NDUFAF3 (C3ORF60), encoding an NDUFAF4 (C6ORF66)-interacting complex I assembly protein, cause fatal neonatal mitochondrial disease

Am J Hum Genet. 2009 Jun;84(6):718-27. doi: 10.1016/j.ajhg.2009.04.020. Epub 2009 May 21.


Mitochondrial complex I deficiency is the most prevalent and least understood disorder of the oxidative phosphorylation system. The genetic cause of many cases of isolated complex I deficiency is unknown because of insufficient understanding of the complex I assembly process and the factors involved. We performed homozygosity mapping and gene sequencing to identify the genetic defect in five complex I-deficient patients from three different families. All patients harbored mutations in the NDUFAF3 (C3ORF60) gene, of which the pathogenic nature was assessed by NDUFAF3-GFP baculovirus complementation in fibroblasts. We found that NDUFAF3 is a genuine mitochondrial complex I assembly protein that interacts with complex I subunits. Furthermore, we show that NDUFAF3 tightly interacts with NDUFAF4 (C6ORF66), a protein previously implicated in complex I deficiency. Additional gene conservation analysis links NDUFAF3 to bacterial-membrane-insertion gene cluster SecF/SecD/YajC and to C8ORF38, also implicated in complex I deficiency. These data not only show that NDUFAF3 mutations cause complex I deficiency but also relate different complex I disease genes by the close cooperation of their encoded proteins during the assembly process.

Publication types

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

MeSH terms

  • Amino Acid Sequence
  • Amino Acid Substitution
  • Calmodulin-Binding Proteins / genetics*
  • Consanguinity
  • DNA Mutational Analysis
  • Electron Transport Complex I / genetics*
  • Electrophoresis, Polyacrylamide Gel
  • Fatal Outcome
  • Female
  • Genetic Complementation Test
  • Humans
  • Infant
  • Infant, Newborn
  • Male
  • Membrane Proteins / genetics*
  • Mitochondrial Diseases / genetics*
  • Mitochondrial Proteins / genetics*
  • Models, Genetic
  • Molecular Sequence Data
  • Pedigree
  • Sequence Homology, Amino Acid


  • Calmodulin-Binding Proteins
  • Membrane Proteins
  • Mitochondrial Proteins
  • NDUFAF3 protein, human
  • NDUFAF4 protein, human
  • Electron Transport Complex I