Resistance to activated protein C (APC resistance) is the most common
cause of thrombophilia and linked to a single point mutation in the fa
ctor V gene (G>A transition at nucleotide 1691). In the past, several
PCR based methods have been proposed to determine the allelostatus of
individual patients from small amounts of blood DNA including PCR foll
owed by restriction fragment length polymorphism detection (PCR-RFLP),
PCR using sequence-specific primers (PCR-SSP) and oligonucleotide lig
ation assay (OLA). Here, we present a novel approach based on the meth
od of peptide nucleic acid(PNA)mediated PCR clamping which is extremel
y sensitive to base pair mismatches. If PNAs specific for the two alle
lic variants are applied separately in each case a clear discriminatio
n between a heterozygous or homozygous normal or homozygous Factor V L
eiden status is possible and no further confirmation step is required.
In a prospective study, 60 patients with suspected venous thrombosis
events were tested and compared to the conventional PCR-RFLP technique
. The concordance between both methods was 100%. PNA-based factor V ge
notyping, therefore, should be considered for large scale screening of
those patients considered to be at risk for deep venous thrombosis.