An increased incidence of POAG among patients' first-degree relatives is well established; relatives of POAG patients have a 22% risk of developing POAG at some point in their lives, whereas the risk for the relatives of controls is 2% to 3%.11 This risk has been shown to be two to five times greater on the maternal side of families.12 However, only two genes, myocilin (MYOC) and optineurin (OPTN), have been established to cause familial POAG with high penetrance. This evidence concerns the gene OPTN and open-angle glaucoma.