A G-to-A mutation at -33 position in the promoter region of thrombomodulin gene and non-O blood group are associated with idiopathic venous thromboembolism: Taiwan Thrombophilia Study

Abstract number: P1390

Lin^* J. S., Shen† M. C., Yu^* Y. Y., Lin^* C. H., Hsueh^* S. Y., Fan^* H. C., Lin† B. B., Hong† M. H., Wang† Y. C.

^*Changhua Christian Hospital, Taiwan; †National Taiwan University Hospital, Taiwan

A G-33 A mutation in the promoter region of thrombomodulin (TM) gene, which is common in Taiwanese but rare in Caucasians, is associated with a decrease of promoter activity. Its association with venous thromboembolism (VTE) remains unclear. The relationship between non-O blood group and VTE has been suggested in Caucasians but rarely mentioned in Asians. We conducted a case-control study to investigate the association of these two factors with VTE in the Taiwanese. 115 unrelated patients with documented idiopathic VTE were recruited. Among them, 26 without any risk factor for VTE, 47 with natural anticoagulant deficiencies, six with other risk factors and 36 without a complete study due to continuous anticoagulation. 115 ambulatory healthy subjects were selected and matched (1:1) to the patients according to sex and age (±2 years). TM G-33 A mutation was detected by PCR and Msp I digestion. ABO blood group was determined by isoagglutination. The adjusted thrombotic risk, odds ratio (95% C.I.), was 1.99 (1.09–3.65) for TM G-33 A carriers and 2.46 (1.37–4.42) for non-O subjects, respectively, in a whole-group analysis. When the major risk factors for Taiwanese VTE, i.e. deficiencies of natural anticoagulants, were considered, the significance of these two potential factors became unremarkable; however, subjects with the major risk factors in combination with either TM G-33 A or non-O blood group carried a higher risk (27.65, 7.04–108.5) than the ones with the major risk factors only (18.11, 1.56–210.8). In conclusion, TM G-33 A and non-O blood group are two additional risk factors for VTE in Taiwanese.