Factor V Leiden (G1691A), the prothrombin 3'-untranslated region variant (G20210A) and thermolabile methylenetetrahydrofolate reductase (C677T): a single genetic test genotypes all three loci--determination of frequencies in the S. Wales population of the UK.

Simultaneous genetic diagnosis of factor V (FV) Leiden (G1691A), the prothrombin variant (G20210A) and the thermolabile methylenetetrahydrofolate reductase (MTHFR) variant (C677T) has been achieved using multiplex heteroduplex analysis. All three loci are amplified in a single polymerase chain reaction (PCR) containing test DNA and three heteroduplex generators, respectively detecting the three nucleotide substitutions. After PCR, the products are analysed directly without further manipulation and the resulting heteroduplex profiles permit straightforward interpretation of the respective genotypes. The multiplex test has been used to assess the prevalence and allele frequency of each of the three nucleotide substitutions in 300 individuals (150 males and 150 females) from the local (S. Wales) population. A prevalence of 8% and an allele frequency of 0.040 +/- 0.015 (95% confidence interval) was obtained for FV Leiden; the prothrombin variant showed a prevalence of 1% and an allele frequency of 0.007 +/- 0.006 (95% confidence interval); the MTHFR mutation showed a prevalence of 60% and an allele frequency of 0.377 +/- 0.039 (95% confidence interval). This method is applicable to investigation of large cohorts of patients with arterial or venous thrombotic disease.