OPTN and open-angle glaucoma: So far, linkage-based approaches have resulted in the discovery of eight causative genes for monogenic POAG namely, MYOC (GLC1A), OPTN (GLC1E), ASB10 (GLC1F), WDR36 (GLC1G), NTF4 (GLC1O), TBK1 (GLC1P), CYP1B1 (GLC3A), and LTBP2 (GLC3D).