PHENOTYPING AND GENOTYPING OF COAGULATION-FACTOR-V LEIDEN

The currently used activated Protein C resistance test demonstrated to be of limited diagnostic value for the detection of the mutant Factor V Leiden. Moreover, this assay is not useful for patients under antic oagulant therapy. A modification of the APC resistance test, applying Factor V deficient plasma is described which demonstrates a specificit y and sensitivity of 1.0. The superiority of the modified APC resistan ce test over the existing APC resistance test was verified by genotypi ng. For that purpose, the Amplification Refractory Mutation System (AR MS) was applied to the detection of the G to A mutation at position 16 91 in the gene encoding coagulation Factor V. The mutation at that pos ition could be easily detected by using each of two allele-specific ol igonucleotide primers concomitantly with one common primer in two sepa rate polymerase chain reactions, thereby amplifying a fragment of 186 base-pairs of the Factor V gene.