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). The gene discussed is CYP1B1; the disease is open-angle glaucoma.