“…Although most studies observe OPTN gene variations associated with NTG, this analysis is difficult to be performed in the Brazilian population, due to the small number of patients with this condition in our country, as observed by Urbano et al who found 3% of NTG among 329 glaucoma patients. 25 POAG is a complex disease, in which different genes, associated to environmental interactions, may contribute in a greater or lesser extension to the development of the glaucomatous damage depending on the ethnic background. This equation explains why the frequency of OPTN mutations is variable among different studies.…”