MTHFR and hyperhomocysteinemia: Recent studies have examined, with conflicting results, the association of NAION with thrombophilic genes such as the methylenetetrahydrofolate reductase (MTHFR) C677T polymorphism and platelet polymorphisms on the glycoprotein Ib alpha gene [2,4,5,11], and with hypertension genes [12], hereditary deficiencies of protein C, protein S and antithrombin III, hyperhomocysteinemia, and primary antiphospholipid syndrome [5,6,13,14].