In Caucasians about 2%–4% of POAG cases are due to MYOC mutations,[73] although it can be as high as 36% in JOAG families.[74] Mutations in OPTN, arguably the second POAG gene, were initially found in 16.7% of families with hereditary and adult onset POAG, and 12% of sporadic patients with POAG. This evidence concerns the gene OPTN and open-angle glaucoma.