F2 and deep vein thrombosis: In a Meta analysis study by Simone et al. involving 11,000 cases and 21,000 controls FV Leiden and Prothrombin 20210 were indicated as moderate risk factors of VTE and the risk was increased in heterozygote carriers of FV Leiden or Prothrombin 20210, however they found no significant association with DVT and homozygous pattern of MTHFR C677T [25].