Low mutant load of mitochondrial DNA G13513A mutation can cause Leigh's disease

Denise M. Kirby, Avihu Boneh, C. W. Chow, Akira Ohtake, Michael T. Ryan, Dominic Thyagarajan, David R. Thorburn

Research output: Contribution to journalArticleResearchpeer-review

102 Citations (Scopus)

Abstract

Respiratory chain complex I deficiency is a common cause of Leigh's disease (LD) and can be caused by mutations in genes encoded by either nuclear or mitochondrial DNA (mtDNA). Most pathogenic mtDNA mutations act recessively and only cause disease when present at high mutant loads (typically >90%) in tissues such as muscle and brain. Two mitochondrial DNA mutations in complex I subunit genes, G14459A in ND6, and T12706C in ND5, have been associated with complex I deficiency and LD. We report another ND5 mutation, G13513A, in three unrelated patients with complex I deficiency and LD. The G13513A mutation was present at mutant loads of approximately 50% or less in all tissues tested, including multiple brain regions. The threshold mutant load for causing a complex I defect in cultured cells was approximately 30%. Blue Native polyacrylamide gel electrophoresis showed that fibroblasts with 45% G13513A mutant load had approximately 50% of the normal amount of fully assembled complex I. Fibroblasts with greater than 97% of the ND6 G14459A mutation had only 20% fully assembled complex I, suggesting that both mutations disrupt complex I assembly or turnover. We conclude that the G13513A mutation causes a complex I defect when present at unusually low mutant load and may act dominantly.

Original languageEnglish
Pages (from-to)473-478
Number of pages6
JournalAnnals of Neurology
Volume54
Issue number4
DOIs
Publication statusPublished - 1 Oct 2003
Externally publishedYes

Cite this