Rapid detection of prothrombotic mutations of prothrombin (G20210A), factor V (G1691A), and methylenetetrahydrofolate reductase (C677T) by real-time fluorescence PCR with the LightCycler.

storage of blood at room temperature is uncertain, but one possibility is that cleavage of the antigen occurs, releasing smaller fragments, each with multiple OVX1 epitopes. Different cutoffs at 7.2, 10.5, or 12.1 kilounits/L have been used in clinical studies (2, 4). The present findings, therefore, are clinically relevant because the assay range is narrow and the effect we have noted can cause an increase of OVX1 concentrations above these cutoffs. The findings have important implications for the collection of samples for OVX1 analysis by radioimmunoassay and for our ongoing ovarian cancer screening trial. It is clear that samples must be collected in plain tubes and the serum either separated immediately or the sample kept at 4 °C until centrifugation is performed. Unfortunately, our screening trial is based on postal transport of blood samples and immediate centrifugation is not possible. We therefore will not be able to incorporate OVX1 measurement into the study protocol unless a method for stabilizing the antigen during transport at room temperature is identified. Fortunately, repetitive freezing at 220 °C and thawing did not significantly affect OVX1 concentrations. This result is reassuring and suggests that earlier OVX1 studies based on serum samples that were separated and stored immediately are likely to be valid even if the samples analyzed had been frozen and thawed on several occasions.