The Prothrombin 20210 A Allele Is Frequently Coinherited in Young Carriers of the Factor V Arg 506 to Gln Mutation With Venous Thrombophilia

To the Editor: Since the discovery of the factor (F) V Arg 506 to Gln mutation (FV:R506Q) as the most common inherited disorder associated to venous thrombophilia[1-6][1] and its apparent cosegregation with other well-established inherited prothrombotic risk factors,[7-12][2]evidence is