MYOC and open-angle glaucoma: Myocilin mutations account for 2% to 4% of POAG and are associated with high IOP, while optineurin mutations may account for 1% of POAG and 2% of normal-tension glaucoma.11 MtDNA variation has been hypothesized to be involved in POAG risk, with studies suggesting increased levels of rare mtDNA variants in POAG cases.13,14 While interesting findings are emerging, systematic studies to date have not always considered the population structure of mtDNA ancestry in their analyses.