MTHFR and open-angle glaucoma: In addition, when the A1298C MTHFR genotypes were compared, both the PCAG (23±5.94 μmol/l, p<0.027) and POAG (16±1.51 μmol/l, p<0.001) groups were found to have significantly elevated levels of tHcy in the AC genotype as compared to the controls (12±1.25 μmol/l; Figure 2).