Functional mutation in the promoter region of thrombomodulin gene in relation to carotid atherosclerosis

Thrombomodulin is an important endothelial anticoagulant protein that decre ases thrombin activity and activates protein C. Our recent study has shown that the G-33A promoter mutation of thrombomodulin gene is associated with coronary artery disease. This study was conducted to determine whether the C-33A mutation in the promoter region of thrombomodulin gene is a genetic r isk factor for ischemic stroke or carotid atherosclerosis. The functional s ignificance of this mutation was also evaluated. We recruited 333 patients (mean age 64 years, 59% male) with ischemic stroke and 257 age- and sex-mat ched controls. in all study participants, carotid atherosclerosis was asses sed by Duplex scanning, and thrombomodulin G-33A promoter mutation was dete cted by single-strand conformation polymorphism. Luciferase reporter gene a ssay was used to assess the influence of this mutation on thrombomodulin pr omoter activity. There was no significant difference in the thrombomodulin G-33A mutation frequency (GA + AA genotypes) between the stroke and the con trol groups (18.3 vs. 24. 1%, P = 0.105). The G-33A mutation frequency was also similar between the study participants with and without carotid athero sclerosis (22.2 vs. 19.8%, P = 0.550). When only younger subjects (age less than or equal to 60 years) were included in the analysis, however, we foun d the mutation occurred more frequently in participants with carotid athero sclerosis (33.3 vs. 17.3%, odds ratio [OR] = 2.38, 95% confidence interval [CI] = 1.16-4.90, P = 0.027). Multiple logistic regression analyses showed that only diabetes mellitus (OR = 3.11, 95% CI = 1.33-7.30. P=0.009) and G- 33A mutation (OR=2.46. 95% CI=1.14-5.29, P=0.021) were associated independe ntly with carotid atherosclerosis in younger subjects. As assessed by lucif erase reporter gene assays, the contructs bearing the G-33A mutation showed a significant decrease (36 +/- 12%) in transcriptional activity in compari son with the wild type constructs. Our findings suggest that G-33A mutation reduces the thrombomodulin promoter activity and is associated with caroti d atherosclerosis in younger subjects. (C) 2001 Elsevier Science Ireland Lt d. All rights reserved.