OPTN and open-angle glaucoma: The majority of them had IOP of less than 22 mm Hg.[64] Two subsequent studies on Caucasian POAG patients, one study involving 801 patients of variable age onsets[75] and one involving 86 adult-onset patients,[76] reported no glaucoma causing mutations in OPTN. In 148 Japanese patients with NTG and 165 with HTG, again no specific glaucoma-causing mutations in OPTN were identified.[77] The third gene for POAG was characterized as WDR36 at GLC1G.[66] In the original study, four mutations were found to be associated with more than 5% of all sporadic cases of POAG.[66]