A meta-analysis of candidate gene polymorphisms and ischemic stroke in 6 study populations: association of lymphotoxin-alpha in nonhypertensive patients.

BACKGROUND AND PURPOSE: Ischemic stroke is a multifactorial disease with a strong genetic component. Pathways, including lipid metabolism, systemic chronic inflammation, coagulation, blood pressure regulation, and cellular adhesion, have been implicated in stroke pathophysiology, and candidate gene polymorphisms in these pathways have been proposed as genetic risk factors. METHODS: We genotyped 105 simple deletions and single nucleotide polymorphisms from 64 candidate genes in 3550 patients and 6560 control subjects from 6 case-control association studies conducted in the United States, Europe, and China. Genotyping was performed using the same immobilized probe typing system and meta-analyses were based on summary logistic regressions for each study. The primary analyses were fixed-effects meta-analyses adjusting for age and sex with additive, dominant, and recessive models of inheritance. RESULTS: Although 7 polymorphisms showed a nominal additive association, none remained statistically significant after adjustment for multiple comparisons. In contrast, after stratification for hypertension, 2 lymphotoxin-alpha polymorphisms, which are in strong linkage disequilibrium, were significantly associated among nonhypertensive individuals: LTA 252A>G (additive model; OR, 1.41 with 95% CI, 1.20 to 1.65; P=0.00002) and LTA 26Thr>Asn (OR, 1.19 with 95% CI, 1.06 to 1.34; P=0.003). LTA 252A>G remained significant after adjustment for multiple testing using either the false discovery rate or by permutation testing. The 2 single nucleotide polymorphisms showed no association in hypertensive subjects (eg, LTA 252A>G, OR, 0.93; 95% CI, 0.84 to 1.03; P=0.17). CONCLUSIONS: These observations may indicate an important role of LTA-mediated inflammatory processes in the pathogenesis of ischemic stroke.

Type 2 diabetes whole-genome association study in four populations: the DiaGen consortium.

Type 2 diabetes (T2D) is a common, polygenic chronic disease with high heritability. The purpose of this whole-genome association study was to discover novel T2D-associated genes. We genotyped 500 familial cases and 497 controls with >300,000 HapMap-derived tagging single-nucleotide-polymorphism (SNP) markers. When a stringent statistical correction for multiple testing was used, the only significant SNP was at TCF7L2, which has already been discovered and confirmed as a T2D-susceptibility gene. For a replication study, we selected 10 SNPs in six chromosomal regions with the strongest association (singly or as part of a haplotype) for retesting in an independent case-control set including 2,573 T2D cases and 2,776 controls. The most significant replicated result was found at the AHI1-LOC441171 gene region.

Association between alcohol consumption and subclinical carotid atherosclerosis: the Study of Health in Pomerania.

BACKGROUND AND PURPOSE: Epidemiologic studies have shown a J-shaped association between alcohol consumption and vascular diseases. However, only few studies have reported on the association between alcohol intake and subclinical atherosclerosis. The aim of the study was to investigate the relation between alcohol intake and carotid intima-media thickness (IMT) in participants of the population-based Study of Health in Pomerania. METHODS: In 1230 men and 1190 women, the mean IMT of the right and left common carotid arteries was measured by B-mode ultrasonography. Alcohol consumption was assessed with a computer-assisted face-to-face interview. RESULTS: In men, carotid IMT as a function of alcohol intake was depicted as a J-shaped curve with a nadir for the alcohol intake category of 61 to 80 g/d. Linear regression models controlled for age, diabetes, systolic blood pressure, leisure time physical activity, food frequency patterns, smoking status, and education revealed a significant inverse association between IMT and alcohol intake < or =80 g/d in men (beta=-0.009, P<0.02), which became insignificant after further controlling for HDL cholesterol and fibrinogen (beta=-0.007, P=NS). In women, neither a J-shaped relation nor significant differences in IMT between the drinking and nondrinking groups were found. CONCLUSIONS: Alcohol consumption is inversely correlated with carotid IMT in men but not in women. However, the total daily level of alcohol intake that shows a maximum protective effect against atherosclerosis is above the threshold where severe alcohol related comorbidity and organ damage have been reported.

Linkage disequilibrium patterns and tagSNP transferability among European populations.

The pattern of linkage disequilibrium (LD) is critical for association studies, in which disease-causing variants are identified by allelic association with adjacent markers. The aim of this study is to compare the LD patterns in several distinct European populations. We analyzed four genomic regions (in total, 749 kb) containing candidate genes for complex traits. Individuals were genotyped for markers that are evenly distributed at an average spacing of approximately 2-4 kb in eight population-based samples from ongoing epidemiological studies across Europe. The Centre d'Etude du Polymorphisme Humain (CEPH) trios of the HapMap project were included and were used as a reference population. In general, we observed a conservation of the LD patterns across European samples. Nevertheless, shifts in the positions of the boundaries of high-LD regions can be demonstrated between populations, when assessed by a novel procedure based on bootstrapping. Transferability of LD information among populations was also tested. In two of the analyzed gene regions, sets of tagging single-nucleotide polymorphisms (tagSNPs) selected from the HapMap CEPH trios performed surprisingly well in all local European samples. However, significant variation in the other two gene regions predicts a restricted applicability of CEPH-derived tagging markers. Simulations based on our data set show the extent to which further gain in tagSNP efficiency and transferability can be achieved by increased SNP density.

Asymptomatic carotid atherosclerosis is associated with circulating chlamydia pneumoniae DNA in younger normotensive subjects in a general population survey.

OBJECTIVE: Chlamydia pneumoniae infection has been associated with atherosclerosis, but serodiagnosis is unreliable in predicting vascular infection. Direct detection of circulating chlamydial DNA in peripheral blood mononuclear cells (PBMCs) was thus evaluated as a marker for cardiovascular risk in a general population survey using the common carotid intima-media thickness (IMT) as surrogate marker of asymptomatic atherosclerosis. METHODS AND RESULTS: C pneumoniae DNA in PBMCs was determined by nested polymerase chain reaction and associated with IMT for 1032 healthy participants of a general population survey who were within the highest or lowest IMT distribution quartile. C pneumoniae DNA was more prevalent in those with increased IMT (13.4% versus 10.7%), but this was not significant in univariate and of borderline significance in multivariate analysis. Testing for potential effect modifications by known strong determinants of an increased IMT in group interaction analysis revealed an independent association between C pneumoniae DNA and IMT in normotensive subjects (odds ratio [OR], 2.06; 95% CI, 1.05 to 4.03; P=0.04) and in those <70 years old (OR, 1.84; 95% CI, 1.06 to 3.19; P=0.03). CONCLUSIONS: Asymptomatic atherosclerosis is associated with circulating C pneumoniae DNA independently of classical cardiovascular risk factors in normotensive subjects and those <70 years old. C pneumoniae has been implicated in atherogenesis. We determined the association of chlamydial DNA in peripheral blood mononuclear cells with the carotid intima-media thickness from 1032 healthy subjects from a general population survey. A stratified group interaction analysis revealed an independent association in normotensive subjects and those <70 years old.

Periodontal disease, but not edentulism, is independently associated with increased plasma fibrinogen levels. Results from a population-based study.

The systemic response to periodontal disease was analyzed in the cross-sectional Study of Health in Pomerania (SHIP). The completed data of 2,738 subjects aged 20 to 59 years were used for logistic regression analysis with an increased plasma fibrinogen level (> or =3.25 g/L according to Clauss) as the dependent variable. Participants were divided into four groups according to the number of periodontal pockets > or =4 mm (0, 1-7, 8-14, > or =15 pocketing). An additional group comprised the 52 edentulous subjects. The adjusted odds ratio (OR) of > or =15 periodontal pockets for increased plasma fibrinogen levels was 1.88 (95% CI: 1.25-2.83). Edentulism per se was not associated with increased plasma fibrinogen levels but was contained in a two-way interaction with the number of cigarettes/day in current smokers (p = 0.031). For edentulous nonsmokers the adjusted OR was 1.10 (95% CI: 0.51-2.39). Furthermore, body mass index, the interaction between gender and body mass index, serum LDL cholesterol, medication, the interaction between LDL cholesterol and medication, aspirin, smoking, school education, chronic bronchitis, and the interaction between alcohol consumption and chronic gastritis were associated with plasma fibrinogen levels. Our results show that periodontal disease but not edentulism per se is associated with an increased plasma fibrinogen level.

Laboratory markers carbohydrate-deficient transferrin, gamma-glutamyltransferase, and mean corpuscular volume are not useful as screening tools for high-risk drinking in the general population: results from the Study of Health in Pomerania (SHIP).

BACKGROUND: Assessment of high-risk drinking in the general population can be problematic: questionnaire-based instruments may carry the problem of random or systematic recall bias, and the effectiveness of screening of single biomarkers has been shown to be insufficient. In this article, we analyze the alcohol intake/biomarker relationship of carbohydrate-deficient transferrin (CDT), gamma-glutamyltransferase (GGT), and erythrocyte mean corpuscular volume (MCV). Specific aims were (1) screening effectiveness comparison of GGT, CDT, and MCV in terms of sensitivity, specificity, and positive (PPVs) and negative predictive values (NPVs) and the effect of covariates on these measures; (2) the comparison of summary measures for the effectiveness of screening: the receiver characteristic curve (ROC) and the area under the ROC; and (3) to answer the question of which covariates effect which biomarkers and whether accounting for relevant covariates increases the prognostic value of biomarkers to levels that allow for application in the general population. METHODS: In a representative cross-sectional health survey in northeast Germany with data collection from 1997 to 2001, 4310 men and women were asked for their recent alcohol consumption and smoking. Biomarkers were analyzed from blood samples. The effectiveness of screening of CDT, GGT, and MCV for high-risk drinking (men: >60 g/day, women: >40 g/day) was analyzed with PPV and ROC curve analysis. RESULTS: For all three biomarkers, PPVs for high-risk drinking are very low (< 50%). There are some effects of covariates on screening effectiveness and on PPV, and knowledge of these covariates increases screening effectiveness, but no subgroup that had a combination of covariate levels and prevalence of high-risk drinking that led to a PPV > 50% could be found. CONCLUSIONS: : Accounting for covariates in the screening procedure does not lead to a sufficient increase in PPV. Screening effectiveness of laboratory markers CDT, GGT, and MCV is insufficient for their application as screening tools for high-risk alcohol drinking in the general population. This was found using self-reported alcohol consumption as an imperfect gold standard, which is a limitation of the study, although self-reports are the standard instrument in comparable epidemiologic studies.

Sex and the risk of restless legs syndrome in the general population.

BACKGROUND: Restless legs syndrome (RLS) is characterized by the desire to move the limbs associated with paresthesias of the legs, a motor restlessness, an intensification of symptoms at rest with relief by activity, and a worsening of symptoms in the evening or at night. Population-based studies are rare, and risk factors in the general population are not known. METHODS: Cross-sectional survey with face-to-face interviews and physical examination among 4310 participants in the Study of Health in Pomerania in northeastern Germany. Participants were aged 20 to 79 years and were randomly selected from population registers. Restless legs syndrome was assessed with standardized, validated questions addressing the 4 minimal criteria for RLS as defined by the International Restless Legs Syndrome Study Group. RESULTS: The overall prevalence of RLS was 10.6%, increasing with age, and women were twice as often affected as men. While nulliparous women had prevalences similar to those among men up to age 64 years, the risk of RLS increased gradually for women with 1 child (odds ratio, 1.98; 95% confidence interval, 1.25-3.13), 2 children (odds ratio, 3.04; 95% confidence interval, 2.11-4.40), and 3 or more children (odds ratio, 3.57; 95% confidence interval, 2.30-5.55). Subjects with RLS had significantly lower quality-of-life scores than those without the syndrome. CONCLUSIONS: Restless legs syndrome is a common disease in the general population, affecting women more often than men. It is associated with reduced quality of life in cross-sectional analysis. Parity is a major factor in explaining the sex difference and may guide further clarification of the etiology of the disease.

Association between behavior-dependent cardiovascular risk factors and asymptomatic carotid atherosclerosis in a general population.

BACKGROUND AND PURPOSE: Physical inactivity and unfavorable dietary and lifestyle patterns are related to cardiovascular disease and premature death. Their relationship to atherosclerosis of the carotid arteries and subsequent stroke is unclear. The objective of this study was to investigate the association between those behavioral cardiovascular risk factors and asymptomatic atherosclerosis of the carotid arteries in a population of former East Germany. METHODS: The Study of Health in Pomerania (SHIP) is a cross-sectional survey in northeast Germany. In 1632 individuals aged 45 to 70 years, high-resolution B-mode ultrasound was used to assess the mean intima-media thickness of the right and left common carotid arteries. Carotid plaques and stenosis were recorded. Physical activity, dietary patterns, and cardiovascular risk factors were assessed in interviews with the use of standardized scales. Physically active participants with optimal dietary patterns were classified in the optimal lifestyle group, and those inactive with unfavorable diet were classified in the unfavorable group. RESULTS: After adjustment for sex and age, significant decreasing trends were found for both intima-media thickness and severe asymptomatic atherosclerosis from unfavorable to optimal lifestyle patterns in never smokers but not in smokers. Regression analysis revealed an increased risk of severe asymptomatic atherosclerosis in subjects with an unfavorable lifestyle pattern compared with those with an optimal pattern (odds ratio 2.68; 95% CI, 1.13 to 6.37), following a significant linear trend. CONCLUSIONS: Physical activity and optimal diet are associated with reduced risk of early atherosclerosis in subjects who never smoked, while no benefit of an otherwise optimal lifestyle is observed in smokers.