Factor V Leiden increases plasma F1+2 levels both in normal and deep venous thrombosis subjects

Background and Objectives. A simple approach to understanding molecular mec hanisms leading to thrombosis is the definition of how genetic factors infl uence biochemical parameters of coagulation. conflicting data have been rep orted regarding the that the genotype of factor V plays in the control of p lasma F1+2 levels. The aim of this study was test whether the factor V Leld en mutation affects F1+2 levels. Design and Methods. We studied the effect of factor V Lelden mutation (dete cted by the polymerase chain reaction technique) on plasma F1+2 levels In 4 18 normal subjects and 39 subjects affected by deep venous thrombosis. Results. In both normal subjects and those with venous thrombosis, heterozy gotes for the Leiden mutation showed significantly higher plasma levels of F1+2 (p<0.0001 and p<0.005, respectively). Subjects with venous thrombosis had a higher allelic fee frequency of the Leiden mutation than normal subje cts (11.5% and 3.1%, respectively), Interpretation and Conclusion. The results indicate that the genotype of fa ctor V Is a determinant of plasma F1+2 concentration. The allelic frequency or Leiden mutation in our normal subjects is higher than that found in oth er Italian populations but similar to that reported ibr populations of nort h- and middle-Europe. This finding is consistent with the peculiar ancestry and history of Friuli (the area in which subjects for this study were recr uited), with respect to other Italian regions. (C)2000, Ferrata Storti Foun dation.