To date, more than 20 linkage loci have been mapped for POAG [4,5], with 3 causal genes, myocilin (MYOC; GLC1A) [6], optineurin (OPTN; GLC1E) [7], and WD repeat domain 36 (WDR36; GLC1G) [8], identified at respective locus. This evidence concerns the gene OPTN and open-angle glaucoma.