MTHFR and Rare hereditary thrombophilia: During hospitalization in our intensive care unit, the results of a thrombophilia investigation were normal; more specifically, she was negative for prothrombin F20210A mutation and factor V (FV) Leiden mutation, heterozygous for methylene tetrahydrofolate eductase (MTHFR) C677T mutation, and heterozygous for MTHFR C1298T mutation.