Successful hunt for quantitative trait locus in thrombophilia.

In recent years, our knowledge of the genetic mechanisms of thrombophilia has advanced considerably. The elucidation of the protein C system with the identification of protein C and protein S deficiencies and activated protein C (APC) resistance due to a factor V gene mutation (FV Leiden) as major risk factors of thrombosis has been instrumental for the rapid progress.1–3 Despite these achievements, our understanding of the genetic contribution to thrombophilia is incomplete, and new technological approaches are tried to elucidate unknown genetic factors. The GAIT (Genetic Analysis of Idiopathic Thrombophilia) project is an effort to use genome-wide linkage screening to identify unknown genetic risk factors. This project in addition allows the identification of genes influencing the normal variation of the concentrations of certain plasma proteins.