OPTN and open-angle glaucoma: Thirty three chromosomal loci have so far been implicated in POAG, of which four genes, Myocilin (MYOC) on GLC1A (1q32) [5], Optineurin (OPTN) [6] on GLC1E (10p25), WDR36 on GLC1G (5q22.3) [7] and NTF4 on GLC1O (19q13.3) [8], [9] have been characterized.