Increased relative mitochondrial DNA content in leucocytes of patients with NAION.
OBJECTIVE
To investigate possible changes in relative mitochondrial DNA (mtDNA) content in patients with non-arteritic anterior ischaemic optic neuropathy (NAION).


METHODS
19 patients with NAION were compared to 32 controls matched for age, sex distribution, and ethnicity. DNA was extracted from leucocytes and competitive multiplex polymerase chain reaction was carried out with two primer pairs (one pair for mtDNA ND1 gene and the other pair for beta actin nuclear gene) in the presence of a fluorescent dye.


RESULTS
The mean relative mtDNA content in controls (0.93 (SD 0.11); 95% CI 0.89 to 0.97) was significantly less than in NAION patients (2.40 (1.05); 95% CI 1.90 to 2.91; p < 0.001). Relative mtDNA content was negatively correlated with Snellen visual acuity (Spearman's rho; r = -0.37; p = 0.022).


CONCLUSIONS
Increased relative mtDNA content in NAION patients may imply a response to oxidative stress, possibly in part because of mitochondrial respiratory chain defects. Significantly more non-synonymous mtDNA nucleotide changes, significantly increased relative mtDNA content, and a significant association between relative mtDNA content and visual acuity all imply that mitochondrial abnormalities may be a risk factor for NAION.
Mitochondrial Research Laboratory, Department of Genetics, King Faisal Specialist Hospital and Research Centre, Riyadh, Kingdom of Saudi Arabia. kamero@kfshrc.edu.sa
K K
KK
Abu-Amero
T M
TM
Bosley
D000328:Adult; D000368:Aged; D016022:Case-Control Studies; D004272:DNA, Mitochondrial / Q000032:analysis*; D004591:Electrophoresis, Polyacrylamide Gel; D005260:Female; D006801:Humans; D007963:Leukocytes, Mononuclear / Q000648:ultrastructure*; D008297:Male; D008875:Middle Aged; D018917:Optic Neuropathy, Ischemic / Q000235:genetics* / Q000503:physiopathology; D016133:Polymerase Chain Reaction / Q000379:methods; D014792:Visual Acuity
D004272:DNA, Mitochondrial