No mutations in genes associated with other types of glaucoma or other inherited optic neuropathies, such as MYOC, OPTN, CYP1B1, WDR36, OPA1, or OPA3, were present in PEX glaucoma patients from Saudi-Arabia.69 The same study found only little evidence of mitochondrial DNA mutations in a minority of PEX glaucoma patients (10%).69 These findings suggest that typical glaucoma-associated genes and mitochondrial abnormalities are less important determinants of PEX glaucoma than other factors related to the formation and accumulation of PEX material. The gene discussed is OPTN; the disease is glaucoma.