MTHFR and Rare hereditary thrombophilia: Some inherited thrombophilia defects, for instance, Factor V G1691A, prothrombotic polymorphisms, Factor II G2021A, and the homozygous TT genotype of the methylenetetrahydrofolate reductase (MTHFR) C677T polymorphism, are linked to increased risk of neonatal arterial thrombosis [19].