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BACKGROUND: The deletion-allele of the angiotensin-converting enzyme (ACE) gene and elevated ACE activity are associated with increased risk of severe hypoglycemia in type 1 diabetes. We explored whether genetic and phenotypic variations in other components of the renin-angiotensin system are similarly associated. METHODS: Episodes of severe hypoglycemia were recorded in 171 consecutive type 1 diabetic outpatients during a 1-year follow-up. Participants were characterized at baseline by gene polymorphisms in angiotensinogen, ACE, angiotensin-II receptor types 1 (AT1R) and 2 (AT2R), and by plasma angiotensinogen concentration and serum ACE activity. RESULTS: Three risk factors for severe hypoglycemia were identified: plasma angiotensinogen concentration in the upper quartile (relative rate [RR] vs. lower quartile 3.1, 95% confidence interval [CI,] 1.4-6.8), serum ACE activity in the upper quartile (RR vs. lower quartile 2.9, 95% CI, 1.3-6.2), and homo- or hemizygosity for the A-allele of the X chromosome-located AT2R 1675G/A polymorphism (RR vs. noncarriers 2.5, 95% CI, 1.4-5.0). The three risk factors contributed independently to prediction of severe hypoglycemia. A backward multiple regression analysis identified a high number of renin-angiotensin system-related risk factors and reduced ability to perceive hypoglycemic warning symptoms (impaired hypoglycemia awareness) as predictors of severe hypoglycemia. CONCLUSIONS: High renin-angiotensin system activity and the A-allele of the AT2R 1675G/A polymorphism associate with high risk of severe hypoglycemia in type 1 diabetes. A potential preventive effect of renin-angiotensin system blocking drugs in patients with recurrent severe hypoglycemia merits further investigation Udgivelsesdato: 2008/3

Context Low levels of high- density lipoprotein ( HDL) cholesterol are inversely related to cardiovascular risk. Whether this is a causal effect is unclear. Objective To determine whether genetically reduced HDL cholesterol due to heterozygosity for 4 loss- of- function mutations in ABCA1 cause increased risk of ischemic heart disease ( IHD). Design, Setting, and Participants Three studies of white individuals from Copenhagen, Denmark, were used: the Copenhagen City Heart Study ( CCHS), a 31-year prospective general population study ( n= 9022; 28 heterozygotes); the Copenhagen General Population Study ( CGPS), a cross- sectional general population study ( n= 31 241; 76 heterozygotes); and the Copenhagen Ischemic Heart Disease Study ( CIHDS), a case- control study ( n= 16 623; 44 heterozygotes). End points in all 3 studies were recorded during the period of January 1, 1976, through July 9, 2007. Main Outcome Measures Levels of HDL cholesterol in the general population, cellular cholesterol efflux, and the association between IHD and HDL cholesterol and genotype. Results Heterozygotes vs noncarriers for 4 ABCA1 mutations ( P1065S, G1216V, N1800H, R2144X) had HDL cholesterol levels of 41 mg/ dL ( interquartile range, 31- 50 mg/ dL) vs 58 mg/ dL ( interquartile range, 46- 73 mg/ dL), corresponding to a reduction in HDL cholesterol of 17 mg/ dL ( P <. 001). A 17- mg/ dL lower HDL cholesterol level in the CCHS was associated with a multifactorially adjusted hazard ratio for IHD of 1.70 ( 95% confidence interval [ CI], 1.57- 1.85). However, for IHD in heterozygotes vs noncarriers, the multifactorially adjusted hazard ratio was 0.67 ( 95% CI, 0.28-1.61; 1741 IHD events) in the CCHS, the multifactorially adjusted odds ratio was 0.82 ( 95% CI, 0.34- 1.96; 2427 IHD events) in the CGPS, and the multifactorially adjusted odds ratio was 0.86 ( 95% CI, 0.32- 2.32; 2498 IHD cases) in the CIHDS. The corresponding odds ratio for IHD in heterozygotes vs noncarriers for the combined

Objectives The renin-angiotensin system may play a role in the pathogenesis of atrial fibrillation, and renin-angiotensin system blockers reduce the risk of atrial fibrillation. We hypothesized that polymorphisms in the angiotensinogen and angiotensin-converting enzyme (ACE) genes encoding proteins in this system predict risk of atrial fibrillation. Methods and results We genotyped 9235 individuals from the Danish general population, The Copenhagen City Heart Study, for the a-20c, g-6a, T174M, and M235T polymorphisms in the angiotensinogen gene and the insertion/deletion (I/D) polymorphism in the ACE gene; rare allele frequencies were 0.16, 0.40, 0.12, 0.41, and 0.49, respectively. Participants had sinus rhythm at inclusion. During 26 years of follow-up, 968 individuals developed atrial fibrillation. Multifactorially adjusted hazard ratios for atrial fibrillation for a-20c ac and cc versus aa genotype were 1.1 (95% confidence interval: 1.0-1.3; P=0.05) and 1.5(1.1-2.1; P=0.01). Compared with double noncarriers (angiotensinogen -20aa and ACE II), double heterozygotes (ac-I/D genotype), and double homozygotes (cc-DD) had hazard ratios for atrial fibrillation of 1.2(0.9-1.6; P=0.06) and 2.4(1.4-4.1; P=0.001). a-20c cc homozygotes above 70 years of age who were overweight severely hypertensive, and had heart failure, had an absolute 10-year risk of atrial fibrillation of 61%. Conclusion Angiotensinogen a-20c genotype alone and in combination with ACE I/D genotype predicts an increased risk of atrial fibrillation. Therefore, genetic variation in the renin-angiotensin system may influence effect of renin-angiotensin system blockers on atrial fibrillation