Other glaucoma-associated mutants of OPTN (H486R, H26D,T202R, E322K) that do not induce death of 661W or RGC-5 cells may still be bona fide glaucoma-causing mutants, which possibly act by indirect mechanisms dependent on the niche in vivo, for example, by activating glial cells that may secrete cytotoxic molecules such as TNF alpha to induce RGC death. This evidence concerns the gene OPTN and glaucoma.