Objective: To make recommendations regarding the appropriate evaluation for the prothrombin G20210A mutation, as reflected by published evidence and the consensus opinion of recognized experts in the field. DAT SOURCES: Review of the medical literature, primarily since 1996.
Data extraction and synthesis: After an initial assessment of the literature, key points defining the condition, and review of the clinical study design, a draft manuscript was prepared and circulated to every participant in the College of American Pathologists Conference on Diagnostic Issues in Thrombophilia before the meeting. Each of the key points and associated recommendations were then presented for discussion at the conference. Recommendations were accepted if a consensus of 70% of experts attending the conference was reached. The results of the discussion were used to revise the manuscript into its final form.
Conclusions: Consensus was reached on several recommendations concerning the criteria for testing for the prothrombin G20210A mutation and for the method of testing. First, a major point of consensus was that the prothrombin G20210A mutation is a significant risk factor for venous thromboembolism (VTE) and that testing should be considered in the initial evaluation of suspected inherited thrombophilia. Second, although several analytic methods are commonly used for genetic testing for the prothrombin mutation, all are generally robust and reliable. The recommendations for testing for the prothrombin mutation parallel those for the factor V Leiden mutation and include patients with a history of recurrent VTE, a first episode of VTE before the age of 50 years, a history of an unprovoked VTE at any age, thromboses in unusual anatomic sites, or an affected first-degree relative with VTE. A history of VTE related to pregnancy or estrogen use and unexplained pregnancy loss during the second or third trimesters were also considered to be indications for testing. Other scenarios remain controversial or not recommended, including general population screening.