Thrombophilia is defined as either an inherited or acquired abnormality of haemostasis inclining affected subjects to thrombosis, mainly because of interaction of multiple inherited and/or acquired predisposing factors [1]. Major inherited factors and their relative risks (RR) for venous thromboembolism (VTE) are summarized in Table 1. Factor V Leiden (FVL, heterozygosity, RR: 3–7; homozygosity, RR:11–80) and the prothrombin gene mutation G20210A (heterozygosity, RR: 3–4; homozygosity, RR:5–10) are the most common causes (50–70 %) of diagnosed thrombophilia.
