ORIGINAL ARTICLE: Genetic determinants of normal variation in coagulation factor (F) IX levels: genome-wide scan and examination of the FIX structural gene

Background: High-normal and elevated plasma FIX activity (FIX:C) levels are associated with increased risk for venous- and possibly arterial-thrombosis. Objective: Because the broad normal range for FIX:C involves a substantial unknown genetic component, we sought to identify quantitative-trait loci (QTLs) for this medically important hemostasis trait. Methods: We performed a genome-wide screen and a resequencing-based variation scan of the known functional regions of every distinct FIX gene (F9) in the genetic analysis of idiopathic thrombophilia project (GAIT), a collection of 398 Spanish-Caucasians from 21 pedigrees. Results: We found no evidence for linkage (LOD scores