Thrombophilia is the disposition for recurrent idiopathic thromboembolism and is currently seen as a multifactorial disease caused by a disbalance of complex regulated hemostasis. Despite intensive diagnostics the exact defect remains unknown in most cases. An established cause that can be diagnosed in 1–2% of affected individuals is a deficiency of protein S which limits thrombin formation as a cofactor of activated protein C. However, the evaluation of pathogenetic relevance of decreased protein S levels is difficult due to the much more often occurring acquired protein S deficiency under certain physiological or pathological circumstances, for example, intake of hormonal contraceptives or systemic inflammation. By adding aggregated genetic data of 136 patients, this publication gives a new perspective on protein S diagnostics and indicates under which circumstances a real, genetic defined deficiency can be postulated with higher probability.
