Increased Fibrinogen Levels among South Asians versus Whites in the United Kingdom Are Not Explained by Common Polymorphisms

Determinants of fibrinogen level among South Asians are not established. In 1997-1999, plasma fibrinogen levels and prevalences of the fibrinogen polymorphisms A alpha Thr312Ala, beta-445G/A, and B beta Arg448Lys and correlates were compared among 100 apparently healthy United Kingdom South Asians and 100 age- and sex-matched Whites. Mean fibrinogen levels were higher in South Asians (3.33 g/liter, 95% confidence interval (CI): 3.16, 3.51) than in Whites (2.84 g/liter, 95% CI: 2.72, 2.96) (p < 0.0001), but genotype distributions were similar. B beta Arg448Lys was related to fibrinogen in South Asians (RR (n = 67): 3.22 g/liter, 95% CI: 3.03, 3.43; RK (n = 26): 3.72 g/liter, 95% CI: 3.65, 4.11; KK (n = 7): 3.07 g/liter, 95% CI: 2.53, 3.72) (p = 0.04) and Whites (p = 0.06). beta-455G/A was related to fibrinogen in Whites (GG (n = 56): 2.68 g/liter, 95% CI: 2.56, 2.86; GA (n = 37): 2.97 g/liter, 95% CI: 2.79, 3.17; AA (n = 5): 3.22 g/liter, 95% CI: 2.85, 3.65) (p = 0.02) and South Asians (p = 0.07). After adjustment for age, gender, body mass index, hypertension, cholesterol, triglycerides, smoking, A alpha Thr312Ala, and beta-455G/A, fibrinogen levels remained significantly higher in South Asians (3.56 g/liter, 95% CI: 3.35, 3.77) than in Whites (3.03 g/liter, 95% CI: 2.85, 3.22) (p < 0.0001). These findings suggest that increased fibrinogen levels among South Asians versus Whites are not due to differences in the prevalence of genetic polymorphisms that encode for fibrinogen.