POAG is a genetically heterogeneous disorder and at least 22 genetic loci have been mapped for POAG of which only GLC1A (myocilin, MYOC), GLC1E (optineurin, OPTN), GLC1G (WD repeat domain 36, WDR36), and GLC3A (cytochrome P4501B1, CYP1B1) have been characterized [2-7]. Here, OPTN is linked to open-angle glaucoma.