Simple and rapid combined genetic diagnosis of mutation (1691 G-->A) of the factor V gene and (20210 G-->A) of the prothrombin gene.

We have developed a rapid method which allows us simultaneously to determine two genetic variations that are associated with an increased risk of venous thrombosis: the 20210 G-->A mutation present in the 3'-UT region of the prothrombin gene and the 1691 G-->A mutation giving rise to factor V Leiden. Our strategy involves the coamplification of exon 10 of the factor V gene and of the region 3' from the prothrombin gene using modified oligonucleotides, permitting the introduction of a single HindIII cleavage site in fragments bearing one of the mutations. As a result of its time- and cost-saving features, this combined method should be considered for screening large numbers of patients.