Association between PPARalpha gene polymorphisms and myocardial infarction.

PPARalpha (peroxisome-proliferator-activated receptor alpha) regulates the expression of genes that are involved in lipid metabolism, tissue homoeostasis and inflammation. Consistent rodent and human studies suggest a link between PPARalpha function and cardiovascular disease, qualifying PPARalpha [PPARA in HUGO (Human Genome Organisation) gene nomenclature] as a candidate gene for coronary artery disease. In the present study, we comprehensively evaluated common genetic variations within the PPARalpha gene and assessed their association with myocardial infarction. First, we characterized the linkage disequilibrium within the PPARalpha gene in an initial case-control sample of 806 individuals from the Regensburg Myocardial Infarction Family Study using a panel of densely spaced SNPs (single nucleotide polymorphisms) across the gene. Single SNP analysis showed significant association with the disease phenotype [OR (odds ratio)=0.74, P=0.012, 95% CI (confidence interval)=0.61-0.94 for rs135551]. Moreover, we identified a protective three-marker haplotype with an association trend for myocardial infarction (OR=0.76, P=0.067, 95% CI=0.56-1.02). Subsequently, we were able to confirm the single SNP and haplotype association results in an independent second case-control cohort with 667 cases from the Regensburg Myocardial Infarction Family Study and 862 control individuals from the WHO (World Health Organization) MONICA (Monitoring of Trends and Determinants in Cardiovascular Disease) Augsburg project (OR=0.87, P=0.046, 95% CI=0.72-0.99 for rs135551 and OR=0.80, P=0.034, 95% CI=0.65-0.98 for the three-marker haplotype respectively). From these cross-sectional association results, we provide evidence that common variations in the PPARalpha gene may influence the risk of myocardial infarction in a European population.

Common polymorphisms in the cannabinoid CB2 receptor gene (CNR2) are not associated with myocardial infarction and cardiovascular risk factors.

Myocardial infarction (MI) is a complex disease. Multiple genes and their interaction with various environmental factors influence the pathogenesis of MI that is thought to be tightly regulated by inflammatory pathways. Recent progress in genetic analysis includes the use of large-scale genome-wide association studies that have proven to be powerful tools even in the analysis of multifactorial phenotypes. However, certain genes are only sparsely represented on the available gene chips and additional candidate gene approaches are necessary. One such example is the CNR2 gene, encoding the cannabinoid receptor 2 (CB2), which has been implicated in mediating anti-inflammatory and anti-atherosclerotic effects in vivo. We therefore hypothesized that genetic variations within the CNR2 gene are associated with the development of MI or classic cardiovascular risk factors. In a large case-control study, 1,968 individuals from the German MI family study were examined with 13 single nucleotide polymorphisms (SNPs) covering CNR2 and the adjacent genes. The association of these SNPs with MI or cardiovascular risk factors, such as arterial hypertension, obesity, hypercholesterolemia and diabetes mellitus, was determined. In allelic and genotypic models, none of the SNPs showed a significant association with MI. Separate analyses for men and women revealed no gender-specific relationship between common genetic variations within the CNR2 gene and MI. Moreover, no significant association between CNR2 gene variants and common cardiovascular risk factors was observed. We therefore provide evidence in a large German population that common polymorphisms within the CNR2 gene confer no susceptibility to MI or to cardiovascular risk factors.

Lymphotoxin-alpha and galectin-2 SNPs are not associated with myocardial infarction in two different German populations.

Recent data provided strong evidence for the association of single nucleotide polymorphisms (SNPs) in the lymphotoxin-alpha (LTA) and galectin-2 (LGALS2) genes with myocardial infarction (MI) in a Japanese population. For populations of other genetic background, the relevance of these polymorphisms in the pathogenesis of MI remains controversial. We aimed to define the role of LTA and LGALS2 SNPs in two German MI populations with markedly different ascertainment strategies. Two different MI populations were studied. In the first population, MI patients were ascertained by a strong family history of MI (n = 1214). Controls were unrelated disease-free participants of the study (n = 1080). The second population included patients suffering from sporadic (nonfamilial) MI from the German KORA register (n = 607). The control group consisted of participants of the WHO MONICA survey in Germany (n = 1492). TaqMan assays were used to determine the genotypes of 4 SNPs in the LTA genomic region and 1 SNP in the LGALS2 gene. Single SNPs in both genomic regions as well as haplotypes in the LTA genomic region were tested for association in various models of inheritance. No association with MI could be found for any of the examined SNPs in the LTA genomic region and LGALS2 gene, or for haplotypes spanning the LTA genomic region. In two MI populations of European descent with markedly different ascertainment strategies, we were not able to identify a significant association of SNPs in the LTA genomic region or the LGALS2 gene with MI. These variants are unlikely to play a significant role in populations of European origin.

The common Y402H variant in complement factor H gene is not associated with susceptibility to myocardial infarction and its related risk factors.

Recently, the genetic variant Y402H in the CFH (complement factor H) gene was associated with an increased risk for MI (myocardial infarction) in a prospective Caucasian cohort. In another nested case-control study, however, the CFH-Y402H variant did not carry susceptibility to MI. The aim of the present study was to test for an association between the CFH-Y402H variant and MI in a large case-control sample with a familial background for CAD (coronary artery disease). A total of 2161 individuals from the German MI family study were studied by questionnaire, physical examination and biochemical analyses. MI patients (n=1188; 51.4+/-8.6 years at first MI) were recruited from families with at least two members affected by MI and/or severe CAD. Spouses, sisters-in-law and brothers-in-law respectively, without MI/CAD were included as unaffected controls (n=973; 56.9+/-9.8 years). Genotyping was performed using a TaqMan assay. The common Y402H variant in the CFH gene was not associated with classical cardiovascular risk factors (diabetes, hypercholesterolaemia, hypertension, obesity, smoking and C-reactive protein serum levels). No association was found between the CFH-Y402H variant and susceptibility to MI. Separate analyses in both men and women revealed no gender-specific influence of the gene variant on cardiovascular risk factors or MI. This investigation was unable to replicate the association between the common CFH-Y402H variant and susceptibility to MI in our large Caucasian population which is enriched for genetic factors. We conclude that the CFH-Y402H variant has no relevant risk-modifying effect in our population.

Reduction of PCR-amplifiable DNA by ethylene oxide treatment of forensic consumables.

A reliable method to provide molecular biology products free of contaminating DNA is of forensic interest. Ethylene oxide (EO) treatment has been demonstrated as an effective method in published studies. This study aimed to address some additional experiments that are closer to forensic practice. In the first part of this study, different consumables such as cotton swabs, latex gloves and micro test tubes were spiked with saliva, blood and skin cells to mimic a real-life contamination scenario. EO treatment was performed for a period of 3, 5, 7, and 10h, respectively. For comparison, gamma and electron beam treatment was applied. In the second part of this study, a cell culture line (K562) was used to apply defined cell counts on cotton swabs followed by EO treatment for 3 and 5h. After extraction of samples, the DNA content was quantified using a real-time PCR based system. STR analysis was performed using a latest generation STR kit to meet current sensitivity limits. A good correlation of real-time PCR results and STR results was observed. This work confirmed the findings of earlier studies showing that chemical EO treatment is much more successful in reducing the amount of PCR-amplifiable DNA than ionising radiation. Furthermore, the efficacy of EO treatment is affected by the nature of the samples. DNA in saliva was more susceptible to damage by EO gas than DNA in blood. Our results show, that accessibility of the sample to EO gas has a strong influence on the method's efficiency. While treatment of samples on cotton swabs packed into gas-permeable bags was very successful, samples inside a closed micro test tube were resistant to the same treatment conditions. Our work with defined K562 cell numbers and multi-copy quantitative PCR could show that a 5h EO treatment results in a 10(5) fold reduction of PCR-amplifiable DNA. Corresponding STR-PCR results also show only sporadic allele calls in the Mini-loci range, providing a reliable interpretation of forensic analysis. Finally, we do recommend an EO treatment of forensic consumables and a multi-copy quantitative PCR approach to establish reliable treatment conditions.

Lack of association between a common polymorphism near the INSIG2 gene and BMI, myocardial infarction, and cardiovascular risk factors.

Epidemiological studies revealed an increasing prevalence of and a steep increase in obesity, a risk factor for cardiovascular disease. Because significant influence of a polymorphism, rs7566605, near the INSIG2 gene on BMI has been shown in the general population and in obesity cohorts, we hypothesized that this polymorphism might also act through an elevated BMI on the development of coronary artery disease (CAD) or myocardial infarction (MI). We pursued two strategies: First, the polymorphism rs7566605 was investigated for association with BMI, CAD/MI, and cardiovascular risk factors in a large German cohort at high risk for CAD and MI (n = 1,460 MI patients) as compared to unrelated healthy controls (n = 1,215); second, we extended our analyses on the families of MI patients and performed family-based association testing (n = 5,390 individuals). The polymorphism rs7566605 was analyzed using TaqMan technology. No deviation from Hardy-Weinberg equilibrium could be observed, and the call rate was 98.2%. No significant associations of rs7566605 with CAD/MI, BMI, and classical cardiovascular risk factors could be detected in the full sample size or in the subgroups. A total of 6,878 individuals were investigated in a population of German MI patients and their family members. Although the number of individuals was large enough, no influence of the rs7566605 INSIG2 polymorphism was detected on BMI and CAD/MI. We therefore conclude that in our sample the SNP rs7566605 near the INSIG2 gene does not influence BMI and is not associated directly with CAD/MI or indirectly through cardiovascular risk factors.

Genome-wide haplotype association study identifies the SLC22A3-LPAL2-LPA gene cluster as a risk locus for coronary artery disease.

We identify the SLC22A3-LPAL2-LPA gene cluster as a strong susceptibility locus for coronary artery disease (CAD) through a genome-wide haplotype association (GWHA) study. This locus was not identified from previous genome-wide association (GWA) studies focused on univariate analyses of SNPs. The proposed approach may have wide utility for analyzing GWA data for other complex traits.

Genetic variants within the LPIN1 gene, encoding lipin, are influencing phenotypes of the metabolic syndrome in humans.

OBJECTIVE: Lipin, a novel molecular protein expressed by adipocytes, has marked effects on adipose tissue mass, insulin sensitivity, and glucose homeostasis. Thus, we hypothesized that genetic variants within LPIN1 are associated with traits of the metabolic syndrome. RESEARCH DESIGN AND METHODS: A total of 15 single nucleotide polymorphisms (SNPs) covering the LPIN1 gene region were genotyped in an age- and sex-stratified sample of the general population (Monitoring Trends and Determinants on Cardiovascular Diseases Study Augsburg; DNA and phenotypes of 1,416 Caucasians). Ten SNPs were also genotyped for replication in an independent sample of 1,030 subjects recruited throughout Germany. The metabolic syndrome was defined via the sum of its core components and, additionally, by a factor score derived from factor analysis. Permutation-based methods were used to test the association between genetic LPIN1 variants and metabolic traits for empirical significance. RESULTS: Linkage disequilibrium (LD) analysis revealed three LD blocks encompassing LPIN1. We identified three associated three-marker haplotypes: one common haplotype (26.8% frequency) increases the risk for the metabolic syndrome (odds ratio 1.6 [95% CI 1.2-2.2]), while the other two, being less common (5.7 and 4.0%), are strongly associated with lower blood pressure levels (systolic blood pressure 127 +/- 18 vs. 135 +/- 20 mmHg; P = 0.0001), a lower BMI (24.6 +/- 3.6 vs. 26.9 +/- 4.1 kg/m(2); P = 3.7 x 10(-7)) and waist circumference (82 +/- 12 vs. 90 +/- 12 cm; P = 3.2 x 10(-8)), lower A1C levels (5.1 +/- 0.7 vs. 5.3 +/- 0.9%; P = 0.0002), as well as a lower metabolic syndrome factor score (-0.67 +/- 1.00 vs. 0.04 +/- 1.24; P = 1.4 x 10(-7)). Furthermore, the frequencies of arterial hypertension (23.7 vs. 46.4%; P = 0.00001), obesity (12.9 vs. 30.8%; P = 0.0003), diabetes (2.2 vs. 8.2%; P = 0.041), and the presence of three or more metabolic syndrome components (3.3 vs. 13.7%; P = 0.002) were significantly lower than in subjects not carrying one of these protective haplotypes. Strong associations were also observed in the replication sample using the same haplotypes but with effects in the opposite direction. CONCLUSIONS These data suggest that allelic variants of the LPIN1 gene have significant effects in human metabolic traits and thus implicate lipin in the pathophysiology of the metabolic syndrome.

Association of common polymorphisms in GLUT9 gene with gout but not with coronary artery disease in a large case-control study.

BACKGROUND: Serum uric acid (UA) levels have recently been shown to be genetically influenced by common polymorphisms in the GLUT9 gene in two genome-wide association analyses of Italian and British populations. Elevated serum UA levels are often found in conjunction with the metabolic syndrome. Hyperuricemia is the major risk factor for gout and has been associated with increased cardiovascular morbidity and mortality. The aim of the present study was to further elucidate the association of polymorphisms in GLUT9 with gout and coronary artery disease (CAD) or myocardial infarction (MI). To test our hypotheses, we performed two large case-control association analyses of individuals from the German MI Family Study. METHODS AND FINDINGS: First, 665 patients with gout and 665 healthy controls, which were carefully matched for age and gender, were genotyped for four single nucleotide polymorphisms (SNPs) within or near the GLUT9 gene. All four SNPs demonstrated highly significant association with gout. SNP rs6855911, located within intron 7 of GLUT9, showed the strongest signal with a protective effect of the minor allele with an allelic odds ratio of 0.62 (95% confidence interval 0.52-0.75; p = 3.2*10(-7)). Importantly, this finding was not influenced by adjustment for components of the metabolic syndrome or intake of diuretics. Secondly, 1,473 cases with severe CAD or MI and 1,241 healthy controls were tested for the same four GLUT9 SNPs. The analyses revealed, however, no significant association with CAD or with MI. Additional screening of genome-wide association data sets showed no signal for CAD or MI within the GLUT9 gene region. CONCLUSION: Thus, our results provide compelling evidence that common genetic variations within the GLUT9 gene strongly influence the risk for gout but are unlikely to have a major effect on CAD or MI in a German population.