APOE and glaucoma: Many more important gene variants have recently been associated with glaucoma risk, such as apolipoprotein E (APOE) [26,27], endothelin receptor type A gene (EDNRA) [28,29], IL-1α [30], methylenetetrahydrofolate reductase (MTHFR) [31,32], and beta-adrenergic receptors [33].