The aim of this study was to determine the role of mitochondrial DNA (mtDNA) mutations in primary open angle glaucoma (POAG) using massively parallel sequencing. POAG patients and disease-negative controls were recruited and underwent ophthalmic assessment and DNA extraction from blood leucocytes. In a subset of this cohort Tenon fibroblasts were harvested at the time of ocular surgery, cultured and DNA was extracted. The mitochondrial genome was amplified in two overlapping fragments (9289bp and 7626bp) by long-range PCR and underwent massively parallel sequencing on the Illumina NextSeq 500. Variant annotation and heteroplasmy levels were analysed using the mtDNA-Server (mtdna-server.uibk.ac.at). Known mtDNA, polymorphisms and novel variants were filtered using MITOMAP and control data. 101 POAG patients and 83 disease-negative controls were recruited; Tenon fibroblasts were acquired at the time of ocular surgery from a sub-set of the study group: POAG patients (n=29) and control (n=13). Analysis of mtDNA mutations in the blood demonstrated there were no significant differences (Fisher exact test at p<0.05) in novel or previously disease associated non-synonymous variants in POAG cases versus controls. There was a significant difference in novel mtDNA variants in the POAG Tenon fibroblasts versus control patient fibroblasts (p<0.05). When comparing the paired samples (blood and Tenon fibroblast mtDNA) there were 2 novel potentially-pathogenic variants in the control tissue that were not seen in the control blood or glaucoma blood or Tenon fibroblasts; in the POAG subset there were 11 novel potentially pathogenic, 9 variants of unknown significance and 4 benign novel variants that were not seen in the POAG blood or control blood or Tenon fibroblasts. Only 1 potentially pathogenic variant (m.8801T>C) was found in paired sample (blood/Tenon fibroblast) in one POAG subject. The high frequency of novel mtDNA variation in the Tenon fibroblasts which were absent from blood derived mtDNA in POAG supports the concept that somatic mtDNA mutation occurs in POAG. Mutations are acquired locally in ocular tissue in POAG and are not inherited or germline. Somatic mtDNA mutations in POAG are likely secondary to the local pathophysiological environment and elucidating the mechanism of induced mtDNA damage may offer novel therapeutic opportunities. This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.
|Journal||Investigative ophthalmology & visual science|
|Publication status||Published - 01 Jul 2019|