In the group with placental abruption, 5.9% of patient were MTHFR homozygous and prothrombin heterozigous (coinheritance), 52.9% MTHFR heterozygous, FV Leiden heterozygous 11.8% and without thrombophilia 35.3%. The gene discussed is MTHFR; the disease is Rare hereditary thrombophilia.