MTHFR and hyperhomocysteinemia: Homocysteine levels in these patients are in the 20-40 μmol/L range.8 Turaka et al.9 reported the case of a 15-year-old girl with unilateral papillophlebitis who had hyperhomocysteinemia and homozygous mutations in MTHFR C677T and A1298C.