A novel mitochondrial DNA deletion in aggressive periodontitis

Background Large scale deletions in mitochondrial DNA (mtDNA) have been associated with aging and degenerative diseases. It has been reported that increased oxidative stress in gingival tissue might cause damage to proteins, lipids and DNA and mtDNA deletion has been proposed as an early marker of oxidative DNA damage. Methods To investigate whether a common 5-kb deletion and other uncharacterized large scale deletions within mitochondrial DNA (mtDNA) exist in aggressive periodontitis, we collected blood and gingival tissue samples from 20 patients with aggressive periodontitis (the AgP group) and 20 age-matched healthy control subjects. We amplified the mtDNA deletions using modified sensitivity nested and long range polymerase chain reaction (PCR) assays. The levels of the common 5-kb deletion in total mtDNA were assessed by quantitative real-time PCR, and the deletions were identified by TA cloning and sequencing. Results We detected a novel 4,745-bp deletion (np8426-np13171), flanked by 18 bp imperfect repeats, in both blood and gingival tissue samples. The difference in the frequency of this deletion for the gingival tissue samples of the AgP group versus the control group was statistically significant (P = 0.008). The relative amount of the 4,745-bp deletion did not differ significantly between the two groups. The common 5-kb deletion also occurred in both groups at similar levels. 8-Hydroxydeoxyguanosine (8-OHdG) levels were higher in blood (P = 0.001) and gingival tissue (P = 0.041) samples in the AgP group compared with the controls. Conclusions These observations suggest that the 4,745-bp mtDNA deletion is associated with aggressive periodontitis and may result from oxidative DNA damage.