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

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.

[1]  D. Thorburn,et al.  Late diagnosis of maternal PKU in a family segregating an arylsulfatse E mutation causing symmetrical chondrodysplasia punctata , 1999 .

[2]  D. Reddihough,et al.  Leigh disease caused by the mitochondrial DNA G14459A mutation in unrelated families , 2000, Annals of neurology.

[3]  H. Schägger,et al.  Blue native electrophoresis for isolation of membrane protein complexes in enzymatically active form. , 1991, Analytical biochemistry.

[4]  P. Asfar,et al.  Recurrent brain hematomas in MELAS associated with an ND5 gene mitochondrial mutation , 2000, Neurology.

[5]  F. Dabbeni-sala,et al.  Melatonin protects against 6‐OHDA‐induced neurotoxicity in rats: a role for mitochondrial complex I activity , 2001, FASEB journal : official publication of the Federation of American Societies for Experimental Biology.

[6]  C Combet,et al.  NPS@: network protein sequence analysis. , 2000, Trends in biochemical sciences.

[7]  M. Hanna,et al.  Is the mitochondrial complex I ND5 gene a hot‐spot for MELAS causing mutations? , 2003, Annals of neurology.

[8]  P. Heckerling Paternal inheritance of mitochondrial DNA. , 2002 .

[9]  N. Pfanner,et al.  Assaying protein import into mitochondria. , 2001, Methods in cell biology.

[10]  S. Dimauro,et al.  Identification of a novel mutation in the mtDNA ND5 gene associated with MELAS. , 1997, Biochemical and biophysical research communications.

[11]  J. Sambrook,et al.  Origin-defective mutants of SV40. , 1980, Cold Spring Harbor symposia on quantitative biology.

[12]  Robert W Taylor,et al.  Leigh disease associated with a novel mitochondrial DNA ND5 mutation , 2002, European Journal of Human Genetics.

[13]  G. Attardi,et al.  Tight Control of Respiration by NADH Dehydrogenase ND5 Subunit Gene Expression in Mouse Mitochondria , 2000, Molecular and Cellular Biology.

[14]  V. Tiranti,et al.  A novel mtDNA mutation in the ND5 subunit of complex I in two MELAS patients , 2001, Annals of neurology.

[15]  S. Rahman,et al.  Decrease of 3243 A-->G mtDNA mutation from blood in MELAS syndrome: a longitudinal study. , 2001, American journal of human genetics.

[16]  J. Christodoulou,et al.  Leigh syndrome: Clinical features and biochemical and DNA abnormalities , 1996, Annals of neurology.

[17]  C. J. Lusty,et al.  Membrane and cytosolic components affecting transport of the precursor for ornithine carbamyltransferase into mitochondria. , 1983, The Journal of biological chemistry.

[18]  I. Nelson,et al.  The mitochondrial DNA G13513A transition in ND5 is associated with a LHON/MELAS overlap syndrome and may be a frequent cause of MELAS , 1999, Annals of neurology.

[19]  E. Harlow,et al.  Using Antibodies: A Laboratory Manual , 1999 .

[20]  D. Turnbull,et al.  Reanalysis and revision of the Cambridge reference sequence for human mitochondrial DNA , 1999, Nature Genetics.

[21]  A. Chomyn Mitochondrial Genetic Control of Assembly and Function of Complex I in Mammalian Cells , 2001, Journal of bioenergetics and biomembranes.

[22]  D. Turnbull,et al.  Deficiency of respiratory chain complex I is a common cause of leigh disease , 1996, Annals of neurology.