That said, multiple families are known to be affected by Mendelian forms of POAG and linkage analyses have identified multiple loci which segregate with disease [7–9], leading to the identification of causal mutations within several genes including myocillin (MYOC), optineurin (OPTN) and WD repeat domain 36 (WDR36) [10–12]. The gene discussed is OPTN; the disease is open-angle glaucoma.