@article {1247, title = {Validation of an atrial fibrillation risk algorithm in whites and African Americans.}, journal = {Arch Intern Med}, volume = {170}, year = {2010}, month = {2010 Nov 22}, pages = {1909-17}, abstract = {

BACKGROUND: We sought to validate a recently published risk algorithm for incident atrial fibrillation (AF) in independent cohorts and other racial groups.

METHODS: We evaluated the performance of a Framingham Heart Study (FHS)-derived risk algorithm modified for 5-year incidence of AF in the FHS (n = 4764 participants) and 2 geographically and racially diverse cohorts in the age range 45 to 95 years: AGES (the Age, Gene/Environment Susceptibility-Reykjavik Study) (n = 4238) and CHS (the Cardiovascular Health Study) (n = 5410, of whom 874 [16.2\%] were African Americans). The risk algorithm included age, sex, body mass index, systolic blood pressure, electrocardiographic PR interval, hypertension treatment, and heart failure.

RESULTS: We found 1359 incident AF events in 100 074 person-years of follow-up. Unadjusted 5-year event rates differed by cohort (AGES, 12.8 cases/1000 person-years; CHS whites, 22.7 cases/1000 person-years; and FHS, 4.5 cases/1000 person-years) and by race (CHS African Americans, 18.4 cases/1000 person-years). The strongest risk factors in all samples were age and heart failure. The relative risks for incident AF associated with risk factors were comparable across cohorts and race groups. After recalibration for baseline incidence and risk factor distribution, the Framingham algorithm, reported in C statistic, performed reasonably well in all samples: AGES, 0.67 (95\% confidence interval [CI], 0.64-0.71); CHS whites, 0.68 (95\% CI, 0.66-0.70); and CHS African Americans, 0.66 (95\% CI, 0.61-0.71). Risk factors combined in the algorithm explained between 47.0\% (AGES) and 63.6\% (FHS) of the population-attributable risk.

CONCLUSIONS: Risk of incident AF in community-dwelling whites and African Americans can be assessed reliably by routinely available and potentially modifiable clinical variables. Seven risk factors accounted for up to 64\% of risk.

}, keywords = {African Continental Ancestry Group, Age Factors, Aged, Aged, 80 and over, Algorithms, Atrial Fibrillation, Blood Pressure, Body Mass Index, Cohort Studies, Electrocardiography, Europe, European Continental Ancestry Group, Female, Follow-Up Studies, Heart Failure, Humans, Hypertension, Incidence, Kaplan-Meier Estimate, Male, Middle Aged, Proportional Hazards Models, Risk Factors, Sex Factors, Systole, United States}, issn = {1538-3679}, doi = {10.1001/archinternmed.2010.434}, author = {Schnabel, Renate B and Aspelund, Thor and Li, Guo and Sullivan, Lisa M and Suchy-Dicey, Astrid and Harris, Tamara B and Pencina, Michael J and D{\textquoteright}Agostino, Ralph B and Levy, Daniel and Kannel, William B and Wang, Thomas J and Kronmal, Richard A and Wolf, Philip A and Burke, Gregory L and Launer, Lenore J and Vasan, Ramachandran S and Psaty, Bruce M and Benjamin, Emelia J and Gudnason, Vilmundur and Heckbert, Susan R} } @article {6819, title = {Genome-wide association study of L-arginine and dimethylarginines reveals novel metabolic pathway for symmetric dimethylarginine.}, journal = {Circ Cardiovasc Genet}, volume = {7}, year = {2014}, month = {2014 Dec}, pages = {864-72}, abstract = {

BACKGROUND: Dimethylarginines (DMA) interfere with nitric oxide formation by inhibiting nitric oxide synthase (asymmetrical DMA [ADMA]) and l-arginine uptake into the cell (ADMA and symmetrical DMA [SDMA]). In prospective clinical studies, ADMA has been characterized as a cardiovascular risk marker, whereas SDMA is a novel marker for renal function and associated with all-cause mortality after ischemic stroke. The aim of the current study was to characterize the environmental and genetic contributions to interindividual variability of these biomarkers.

METHODS AND RESULTS: This study comprised a genome-wide association analysis of 3 well-characterized population-based cohorts (Framingham Heart Study [FHS; n=2992], Gutenberg Health Study [GHS; n=4354], and Multinational Monitoring of Trends and Determinants in Cardiovascular Disease Study [MONICA]/Cooperative Health Research in the Augsburg Area, Augsburg, Bavaria, Germany [KORA] F3 [n=581]) and identified replicated loci (DDAH1, MED23, Arg1, and AGXT2) associated with the interindividual variability in ADMA, l-arginine, and SDMA. Experimental in silico and in vitro studies confirmed functional significance of the identified AGXT2 variants. Clinical outcome analysis in 384 patients of the Leeds stroke study demonstrated an association between increased plasma levels of SDMA, AGXT2 variants, and various cardiometabolic risk factors. AGXT2 variants were not associated with poststroke survival in the Leeds study or were they associated with incident stroke in the Cohorts for Heart and Aging Research in Genomic Epidemiology (CHARGE) consortium.

CONCLUSIONS: These genome-wide association study support the importance of DDAH1 and MED23/Arg1 in regulating ADMA and l-arginine metabolism, respectively, and identify a novel regulatory renal pathway for SDMA by AGXT2. AGXT2 variants might explain part of the pathogenic link between SDMA, renal function, and outcome. An association between AGXT2 variants and stroke is unclear and warrants further investigation.

}, keywords = {Adult, Aged, Amidohydrolases, Arginine, Binding Sites, Cohort Studies, Female, Genetic Loci, Genome-Wide Association Study, Genotype, HEK293 Cells, Humans, Male, Mediator Complex, Middle Aged, Polymorphism, Single Nucleotide, Protein Structure, Tertiary, Risk Factors, Stroke, Substrate Specificity, Transaminases}, issn = {1942-3268}, doi = {10.1161/CIRCGENETICS.113.000264}, author = {L{\"u}neburg, Nicole and Lieb, Wolfgang and Zeller, Tanja and Chen, Ming-Huei and Maas, Renke and Carter, Angela M and Xanthakis, Vanessa and Glazer, Nicole L and Schwedhelm, Edzard and Seshadri, Sudha and Ikram, Mohammad Arfan and Longstreth, William T and Fornage, Myriam and K{\"o}nig, Inke R and Loley, Christina and Ojeda, Francisco M and Schillert, Arne and Wang, Thomas J and Sticht, Heinrich and Kittel, Anja and K{\"o}nig, J{\"o}rg and Benjamin, Emelia J and Sullivan, Lisa M and Bernges, Isabel and Anderssohn, Maike and Ziegler, Andreas and Gieger, Christian and Illig, Thomas and Meisinger, Christa and Wichmann, H-Erich and Wild, Philipp S and Schunkert, Heribert and Psaty, Bruce M and Wiggins, Kerri L and Heckbert, Susan R and Smith, Nicholas and Lackner, Karl and Lunetta, Kathryn L and Blankenberg, Stefan and Erdmann, Jeanette and M{\"u}nzel, Thomas and Grant, Peter J and Vasan, Ramachandran S and B{\"o}ger, Rainer H} }