Specific haplotypes of the P-selectin gene are associated with myocardial infarction

Host genetic basis of COVID-19: from methodologies to genes

The COVID-19 pandemic caused by the severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) is having a massive impact on public health, societies, and economies worldwide. Despite the ongoing vaccination program, treating COVID-19 remains a high priority; thus, a better understanding of the disease is urgently needed. Initially, susceptibility was associated with age, sex, and other prior existing comorbidities. However, as these conditions alone could not explain the highly variable clinical manifestations of SARS-CoV-2 infection, the attention was shifted toward the identification of the genetic basis of COVID-19. Thanks to international collaborations like The COVID-19 Host Genetics Initiative, it became possible the elucidation of numerous genetic markers that are not only likely to help in explaining the varied clinical outcomes of COVID-19 patients but can also guide the development of novel diagnostics and therapeutics. Within this framework, this review delineates GWAS and Burden test as traditional methodologies employed so far for the discovery of the human genetic basis of COVID-19, with particular attention to recently emerged predictive models such as the post-Mendelian model. A summary table with the main genome-wide significant genomic loci is provided. Besides, various common and rare variants identified in genes like TLR7, CFTR, ACE2, TMPRSS2, TLR3, and SELP are further described in detail to illustrate their association with disease severity.

SELP Asp603Asn and severe thrombosis in COVID-19 males

Thromboembolism is a frequent cause of severity and mortality in COVID-19. However, the etiology of this phenomenon is not well understood. A cohort of 1186 subjects, from the GEN-COVID consortium, infected by SARS-CoV-2 with different severity was stratified by sex and adjusted by age. Then, common coding variants from whole exome sequencing were mined by LASSO logistic regression. The homozygosity of the cell adhesion molecule P-selectin gene (SELP) rs6127 (c.1807G > A; p.Asp603Asn) which has been already associated with thrombotic risk is found to be associated with severity in the male subcohort of 513 subjects (odds ratio = 2.27, 95% Confidence Interval 1.54-3.36). As the SELP gene is downregulated by testosterone, the odd ratio is increased in males older than 50 (OR 2.42, 95% CI 1.53-3.82). Asn/Asn homozygotes have increased D-dimers values especially when associated with poly Q ≥ 23 in the androgen receptor (OR 3.26, 95% CI 1.41-7.52). These results provide a rationale for the repurposing of antibodies against P-selectin as adjuvant therapy in rs6127 male homozygotes especially if older than 50 or with an impaired androgen receptor.

Putative functional non-coding polymorphisms in SELP significantly modulate sP-selectin levels, arterial stiffness and type 2 diabetes mellitus susceptibility

BACKGROUND

P-selectin, encoded by SELP, has been implicated as an important molecule in the development of arterial stiffness, consequently leading to vascular complications in T2DM. SELP polymorphisms and increased levels of soluble P-selectin (sP-selectin) have been shown to be associated with several inflammatory diseases. The present work was designed to assess nine putative functional non-coding SELP variants in relation to sP-selectin levels and arterial stiffness in T2DM.

METHODS

The genetic distribution of rs3917655, rs3917657, rs3917739, rs2235302, rs3917843 was determined by restriction fragment length polymorphism-polymerase chain reaction (RFLP-PCR). Genotyping of rs3917779 was performed by tetra primer amplification-refractory mutation system (ARMS)- PCR. Three SNPs i.e. rs3917853, rs3917854, rs3917855 were genotyped by Sanger sequencing. Construction of haplotypes was performed using PHASE software. The data thus obtained was analyzed by appropriate statistical tools.

RESULTS

Two non-coding variants i.e. rs3917657 and rs3917854 of SELP were found to be associated with 2 and 1.7 -fold risk of disease development respectively. However, one non-coding variant rs2235302 was found to provide protection against disease development. Furthermore, variant allele of rs3917854 in T2DM patients was found to be associated with 2.07-fold very high vascular risk. Non-coding haplotype GCAGGCCGC was conferring 4.14-fold risk of disease development. Furthermore, overall sP-selectin levels were higher in T2DM patients when segregated according to genotypes as well as haplotypes. Significant genotype- phenotype correlation was observed for rs3917655 as well as rs3917739 variant in patients and for rs3917854 in controls. In vascular risk categories, a significant genotype- phenotype correlation was observed for rs3917655 and rs2235302. Furthermore, patients with CCGGGCCGC haplotype in high risk category were observed with higher levels of sP-selectin as compared to other haplotypes (p < 0.05).

CONCLUSIONS

Non-coding SELP variants may significantly modulate sP-selectin levels, vascular risk and T2DM susceptibility.

Reduced miR-26b Expression in Megakaryocytes and Platelets Contributes to Elevated Level of Platelet Activation Status in Sepsis

In sepsis, platelets may become activated via toll-like receptors (TLRs), causing microvascular thrombosis. Megakaryocytes (MKs) also express these receptors; thus, severe infection may modulate thrombopoiesis. To explore the relevance of altered miRNAs in platelet activation upon sepsis, we first investigated sepsis-induced miRNA expression in platelets of septic patients. The effect of abnormal Dicer level on miRNA expression was also evaluated. miRNAs were profiled in septic vs. normal platelets using TaqMan Open Array. We validated platelet miR-26b with its target SELP (P-selectin) mRNA levels and correlated them with clinical outcomes. The impact of sepsis on MK transcriptome was analyzed in MEG-01 cells after lipopolysaccharide (LPS) treatment by RNA-seq. Sepsis-reduced miR-26b was further studied using Dicer1 siRNA and calpain inhibition in MEG-01 cells. Out of 390 platelet miRNAs detected, there were 121 significantly decreased, and 61 upregulated in sepsis vs. controls. Septic platelets showed attenuated miR-26b, which were associated with disease severity and mortality. SELP mRNA level was elevated in sepsis, especially in platelets with increased mean platelet volume, causing higher P-selectin expression. Downregulation of Dicer1 generated lower miR-26b with higher SELP mRNA, while calpeptin restored miR-26b in MEG-01 cells. In conclusion, decreased miR-26b in MKs and platelets contributes to an increased level of platelet activation status in sepsis.

Minor allele of the factor V K858R variant protects from venous thrombosis only in non-carriers of factor V Leiden mutation

Factor V serves an important role in the regulation of blood coagulation. The rs6025 (R534Q) and rs4524 (K858R) polymorphisms in the F5 gene, are known to influence the risk of venous thrombosis. While the rare Q534 (factor V Leiden) allele is associated with an increased risk of venous thrombosis, the minor R858 allele is associated with a lower risk of disease. However, no study has deeply examined the cumulative impact of these two variations on venous thrombosis risk. We study the association of these polymorphisms with the risk of venous thrombosis in 4 French case-control populations comprising 3719 patients and 4086 controls. We demonstrate that the Q534 allele has a dominant effect over R858. Besides, we show that in individuals not carrying the Q534 allele, the protective effect of the R858 allele acts in a dominant mode. Thrombin generation-based normalized activated protein C sensitivity ratio was lower in the 858R/R homozygotes than in the 858K/K homozygotes (1.92 ± 1.61 vs 2.81 ± 1.57, p = 0.025). We demonstrate that the R858 allele of the F5 rs4524 variant protects from venous thrombosis only in non-carriers of the Q534 allele of the F5 rs6025. Its protective effect is mediated by reduced factor VIII levels and reduced activated protein C resistance.

The TRKB rs2289656 genetic polymorphism is associated with acute suicide attempts in depressed patients: A transversal case control study

INTRODUCTION

Suicide Attempts (SA) are the main complications of Major Depressive Episodes (MDE) and are difficult to predict. Suicide is associated with the expression of Receptor Tyrosin-Kinase B (TRKB), the receptor of the Brain Derived Neurotrophic Factor (BDNF) involved in MDE. However, the impact of its genetic polymorphisms as predictive factors of SA should be clarified. Our main aim is to assess the association of 8 TRKB genetic polymorphisms and SA in depressed patients.

MATERIAL AND METHODS

In 624 patients currently experiencing an MDE in the context of Major Depressive Disorder (MDD) (METADAP study), we assessed the association between 8 TRKB genetic polymorphisms (rs1778933, rs1187352, rs2289658, rs2289657, rs2289656, rs3824519, rs56142442 and rs1439050) and acute (previous month) or past (older than one month) SA. Bonferroni corrections and multivariate analysis adjusted for age, sex, level of education, marital status, Hamilton Depression Rating Scale score and previous MDE were used.

RESULTS

The rs2289656 was associated with acute SA (CC = 28.5%, CT = 15.0% and TT = 11.5%, p = 0.0008). However, the other SNPs were not. Patients with the CC genotype had a higher rate of acute SA (28.5%) as compared to T carriers (14.6%) (adjusted OR = 2.2, CI95% [1.4; 3.5], p<0.0001).

CONCLUSION

The TRKB rs2289656 CC genotype is associated with a 2.2 fold higher risk of acute SA in depressed patients. If this result could be confirmed, this TRKB SNP may be assessed to contribute to the prediction of SA in depressed patients.

Association of SELP Polymorphisms with Soluble P-Selectin Levels and Vascular Risk in Patients with Type 2 Diabetes Mellitus: A Case-Control Study

P-selectin, an adhesion molecule, is encoded by SELP and known as biomarker of endothelial as well as platelet dysfunction. SELP polymorphisms (rs6136, rs6127, and rs6125) and raised levels of soluble P-selectin (sP-selectin) have been associated with several disease conditions. The present study was aimed to determine the association of SELP variants and sP-selectin levels as well as vascular risk in Type 2 diabetes mellitus (T2DM) patients. The frequency of rs6136, rs6127, and rs6125 was assessed by restriction fragment length polymorphism-polymerase chain reaction (RFLP-PCR). sP-selectin levels were measured using commercially available kits. Haplotypes were constructed using PHASE software. The data obtained from the above-said analyses was subjected to suitable statistical analyses. sP-selectin levels (ng/ml) were significantly higher in patients as compared to controls (p < 0.001). Out of total, 22% of patients were found to have very high vascular risk, 43.2% with high vascular risk, while 34.4% with moderate vascular risk. For both rs6136 and rs6127, frequency of variant allele was found to be significantly higher in patients as compared to controls and accounted for 2.4- and 1.5-fold risk of disease development, respectively. CAG was found to be associated with 4.5-fold risk towards disease development. In contrast, AGG was conferring the protective effect. Significantly high sP-levels were observed in patients with homozygous wild genotype of rs6136, all genotypes of rs6127, and heterozygous genotype of rs6125 as compared to respective controls. Significant difference was observed in P-selectin levels within moderate-risk category for rs6136. When compared between the categories, significant difference was observed for rs6136 and rs6127. Furthermore, patients with haplotypes AAA, AGA, and AGG were found to have significantly high sP-selectin levels as compared to controls. Significant difference in sP-selectin levels was observed within very high-risk as well as high-risk category. When compared between the categories, significant difference was observed for AGA and AGG haplotypes. The studied polymorphisms of SELP have shown significant association with sP-selectin levels as well as vascular risk in T2DM patients.

The association of β-arrestin2 polymorphisms with response to antidepressant treatment in depressed patients

The study of genetic polymorphisms involved in antidepressants (AD) response is essential to provide a personalized medicine approach in the field of depression. β-arrestin 2 (ARRB2) is a candidate gene in the pharmacogenetics of AD as it is involved in the signaling cascade downstream of numerous neurotransmitter receptors. We investigated the association between five ARRB2 single nucleotide polymorphisms (SNPs): rs1045280, rs2036657, rs4790694, rs3786047 and rs452246, and response to AD treatment in a sample of 569 patients with a major depressive episode treated for 6months. We show that GG/GT patients for rs4522461 (n=534) and AA/AC patients for rs4790694 (n=244) have a lower response to AD than other genotype groups (HDRS score of 10.9 vs 8.0 after 6months, multivariate analysis: p=0.03; 12.2 vs 9.6, p=0.02, respectively). These data provide additional evidence that β-arrestin 2 is a regulator of intracellular signal transduction processes involved in AD treatment.

Structural and functional impact of SNPs in P-selectin gene: A comprehensive in silico analysis

P-selectin is an adhesion molecule which plays an important role in the development of inflammation. It is encoded by the SELP gene located on chromosome 1q21-q24. Various single nucleotide polymorphisms (SNPs) ofSELPhave been reported to be associated with various inflammatory disease conditions. The genetics behind these diseases could be better understood by knowing the structural and functional impact of various genetic determinants ofSELP. So far, this is the first comprehensive and systematicin silicoanalysis of SNPs inSELP. A total of 2780 SNPs ofSELPwere retrieved from NCBI dbSNP. Only conserved and validated SNPs with minor allele frequency (MAF) ≥ 0.05 were subjected to further analysis. Based on these criteria, we selected 4 non-synonymous SNPs (nsSNPs) and 119 non-coding SNPs (ncSNPs). The nsSNPs were analyzed for deleterious effects using SIFT, Polyphen-2, nsSNPAnalyzer, SNP & Go, SNPs3, Mutperd and I-mutant web tools. The template prediction for variant structure modeling was performed using MUSTER and SWISS-MODEL. The functional impact of ncSNPs was analyzed by SNPinfo and RegulomeDB. Thein silicoanalysis predicted 3 nsSNPs and 21 ncSNPs as potential candidates for future case-control association studies and functional analysis ofSELP.

A Statistical Approach for Testing Cross-Phenotype Effects of Rare Variants

Increasing empirical evidence suggests that many genetic variants influence multiple distinct phenotypes. When cross-phenotype effects exist, multivariate association methods that consider pleiotropy are often more powerful than univariate methods that model each phenotype separately. Although several statistical approaches exist for testing cross-phenotype effects for common variants, there is a lack of similar tests for gene-based analysis of rare variants. In order to fill this important gap, we introduce a statistical method for cross-phenotype analysis of rare variants using a nonparametric distance-covariance approach that compares similarity in multivariate phenotypes to similarity in rare-variant genotypes across a gene. The approach can accommodate both binary and continuous phenotypes and further can adjust for covariates. Our approach yields a closed-form test whose significance can be evaluated analytically, thereby improving computational efficiency and permitting application on a genome-wide scale. We use simulated data to demonstrate that our method, which we refer to as the Gene Association with Multiple Traits (GAMuT) test, provides increased power over competing approaches. We also illustrate our approach using exome-chip data from the Genetic Epidemiology Network of Arteriopathy.

Significant effect of VEGFA polymorphisms on the clinical outcome of metastatic colorectal cancer patients treated with FOLFIRI-cetuximab

AIM

The efficacy of a cetuximab-based regimen used to treat metastatic colorectal cancer (mCRC) could be influenced by VEGFA polymorphisms.

MATERIALS & METHODS

We studied the effects of five polymorphisms in the VEGFA gene (-2549D/I, -1154G/A, -460T/C, +405G/C and +936C/T) on the outcome of 98 mCRC patients treated with FOLFIRI plus cetuximab.

RESULTS

Patients homozygous for the -2549D, -1154G and -460T alleles did exhibit higher response rates to treatment and longer progression-free survival compared with others. In addition, the DGTGC and IGCGC haplotypes were significantly associated with a lower risk of disease progression.

CONCLUSION

These findings suggest that VEGFA genetic variations might influence response/resistance of FOLFIRI plus cetuximab treatment in mCRC patients.

Polymorphisms of inflammatory markers and risk of essential hypertension in Tatars from Russia

Essential hypertension (EH) is a common disease with a clear genetic component. Inflammation and endothelial dysfunction play a prominent role in the development of persistent blood pressure elevation. The aim of the current study was to detect an association between EH and polymorphic markers in genes encoding for molecules involved in the control of intercellular interactions during the inflammation process. We analysed SNPs in SELE, SELP, SELL, ICAM1, VEGFA, IL1B, IL6, IL10 and IL12B genes in a group of 534 men of Tatar ethnicity (217 patients with EH and 317 controls). Using a Markov chain Monte-Carlo-based approach (APSampler), we found genotype and allelic combinations associated with EH. The most significant associations were observed for SELE rs2076059*C-SELP rs6131*A-VEGFA -2549*I-IL1B rs16944*C (p = 3.42 × 10(-5), FDR q = 0.035) and SELE rs2076059*C-SELP rs6131*A-IL12B rs3212227*C-IL1B rs16944*C (p = 323 × 10(-4), FDR q = 0.035).

Biomarkers for arterial and venous thrombotic disorders

The haemostatic system maintains the blood in a fluid state, but allows rapid clot formation at sites of vascular injury to prevent excessive bleeding. Unbalances within the haemostatic system can lead to thrombosis. Inspite of successful research our understanding of the disease pathogenesis is still incomplete. There is great hope that genetic, genomic, and epigenetic discoveries will enhance the diagnostic capability, and improve the treatment options. During the preceding 20 years, the identification of polymorphisms and the elucidation of their role in arterial and venous thromboses became an important area of research. Today, a large body of data is available regarding associations of single nucleotide polymorphisms (SNPs) in candidate genes with plasma concentrations and e. g. the risk of ischaemic stroke or myocardial infarction. However, the results for individual polymorphisms and genes are often controversial. It is now well established that besides acquired also hereditary risk factors influence the occurrence of thrombotic events, and environmental factors may add to this risk. Currently available statistical methods are only able to identify combined risk genotypes if very large patient collectives (>10,000 cases) are tested, and appropriate algorithms to evaluate the data have yet to be developed. Further research is needed to understand the functional effects of genetic variants in genes of blood coagulation proteins that are critical to the pathogenesis of arterial and venous thrombotic disorders. In this review genetic variants in selected genes of the haemostatic system and their relevance for arterial and venous thrombosis will be discussed.

Impact of variables of the P-selectin - P-selectin glycoprotein ligand-1 axis on leukocyte-platelet interactions in cardiovascular disease

The formation of leukocyte-platelet aggregates (LPA), through the P-selectin - P-selectin glycoprotein ligand (PSGL)-1 axis, plays a pivotal role in atherothrombosis. In order to investigate the influence of platelet (pP-selectin) and soluble P-selectin (sP-selectin), and of variations in the genes encoding for P-selectin (SELP) and PSGL-1 (SELPLG) on LPA formation, we assessed monocyte (MPA)- and neutrophil-platelet aggregates (NPA) as well as pP-selectin by flow cytometry in 263 patients undergoing angioplasty and stenting. sP-selectin was determined by ELISA, the SELP Pro715 allele and the SELPLG Ile62 allele were determined by allele specific PCR. The Pro715 allele was significantly associated with lower levels of in vivo pP-selectin and sP-selectin, while agonists´ inducible pP-selectin was not influenced by the Pro715 allele. PP-selectin was significantly associated with MPA and NPA formation. The in vivo formation of MPA and NPA depended to 19 % and 7.4 %, respectively, on in vivo pP-selectin, irrespective of the Pro715 allele and the Ile62 allele carrier status. TRAP-6 inducible MPA and NPA depended to 34 % and 27 %, respectively, on TRAP-6 inducible pP-selectin, but were independent of the Pro715 allele carrier status. Carriers of the Ile62 allele showed a stronger correlation between TRAP-6 inducible pP-selectin and TRAP-6 inducible MPA/NPA than non-carriers. Furthermore, TRAP-6 inducible NPA were higher in Ile62 allele carriers, which suggests higher thrombin sensitivity. In conclusion, our findings point to the significant role of pP-selectin for MPA and NPA formation, while other variables like sP-selectin, the SELP Pro715 allele and the SELPLG Ile62 allele have less influence.

Association of PS gene polymorphism and soluble P-selectin levels in atrial fibrillation thromboembolism population in Xinjiang

To investigate the association between the polymorphism of P choose element (p. selectin, PS) and soluble P-selectin levels in atrial fibrillation (AF) thromboembolism in Han and Uigur population of Xinjiang.

METHOD

Using ELISA method determination of plasma level of sPs. The frequency distributions of SNP sP-selectin gene promoter (-2123C/G) and SNP in exon region (Thr715Pro) were investigated by polymerase chain reaction (PCR)-restriction fragment length polymorphism and direct DNA sequence analysis among 302 Xinjiang Uigur and 340 age- and sex-matched Han people.

RESULTS

Cases sPs exist significant difference serum level and the control group. The frequencies of the -2123C/G allele among the Uigur population had no significant differences from those of the Han population. Thr715Pro did not show any polymorphism in the two populations.

CONCLUSIONS

The sP-selectin gene polymorphisms are associated with serum sP-selectin levels or thromboembolic events, suggesting that the patients with nonvalvular AF and thromboembolic events may have genetic susceptibility.

Genetics of coronary heart disease with reference to ApoAI-CIII-AIV gene region

Cardiovascular diseases are affected by multiple factors like genetic as well as environmental hence they reveal factorial nature. The evidences that genetic factors are susceptible for developing cardiovascular diseases come from twin studies and familial aggregation. Different ethnic populations reveal differences in the prevalence coronary artery disease (CAD) pointing towards the genetic susceptibility. With progression in molecular techniques different developments have been made to comprehend the disease physiology. Molecular markers have also assisted to recognize genes that may provide evidences to evaluate the role of genetic factors in causation of susceptibility towards CAD. Numerous studies suggest the contribution of specific “candidate genes”, which correlate with various roles/pathways that are involved in the coronary heart disease. Different studies have revealed that there are large numbers of genes which are involved towards the predisposition of CAD. However, these reports are not consistent. One of the reasons could be weak contribution of genetic susceptibility of these genes. Genome wide associations show different chromosomal locations which dock, earlier unknown, genes which may attribute to CAD. In the present review different ApoAI-CIII-AIV gene clusters have been discussed.

Pharmacogenomic association of nonsynonymous SNPs in SIGLEC12, A1BG, and the selectin region and cardiovascular outcomes

We sought to identify novel pharmacogenetic markers associated with cardiovascular outcomes in patients with hypertension on antihypertensive therapy. We genotyped a 1:4 case:control cohort (n=1345) on the Illumina HumanCVD Beadchip from the INternational VErapamil SR-Trandolapril STudy (INVEST), where participants were randomized to a β-blocker strategy or a calcium channel blocker strategy. Genome-spanning single nucleotide polymorphism (SNP)×treatment interaction analyses of nonsynonymous SNPs were conducted in white and Hispanic race/ethnic groups. Top hits from whites were tested in Hispanics for consistency. A genetic risk score was constructed from the top 3 signals and tested in the Nordic Diltiazem study. SIGLEC12 rs16982743 and A1BG rs893184 had a significant interaction with treatment strategy for adverse cardiovascular outcomes (INVEST whites and Hispanics combined interaction P=0.0038 and 0.0036, respectively). A genetic risk score, including rs16982743, rs893184, and rs4525 in F5, was significantly associated with treatment-related adverse cardiovascular outcomes in whites and Hispanics from the INVEST study and in the Nordic Diltiazem study (meta-analysis interaction P=2.39×10(-5)). In patients with a genetic risk score of 0 or 1, calcium channel blocker treatment was associated with lower risk (odds ratio [95% confidence interval]=0.60 [0.42-0.86]), and in those with a genetic risk score of 2 to 3, calcium channel blocker treatment was associated with higher risk (odds ratio [95% confidence interval]=1.31 [1.08-1.59]). These results suggest that cardiovascular outcomes may differ based on SIGLEC12, A1BG, F5 genotypes, and antihypertensive treatment strategy. These specific genetic associations and our risk score provide insight into a potential approach to personalized antihypertensive treatment selection.

The Thr715Pro variant impairs terminal glycosylation of P-selectin

P-selectin variant 715Pro is associated with lower concentrations of plasma P-selectin and reduced risk for thrombosis. We examined the influence of 715Pro on P-selectin synthesis, post-translational processing, surface expression and function using HEK293 cells, which do not express endogenous P-selectin. Mass spectrometry revealed that HEK293 cells produced recombinant P-selectin which has a glycosylation pattern comparable to platelet P-selectin. Compared to wild-type transfectants, 715Pro transfectants have ~50% less terminally glycosylated P-selectin and accumulate more immature P-selectin in Golgi. Following Brefeldin A treatment, the majority of 715Pro P-selectin is not modified by Golgi enzymes, while wild-type P-selectin undergoes complete modification. Flow cytometry revealed that 715Pro transfectants have ~20% less P-selectin on the cell surface compared to wild-type transfectants. Secretion of P-selectin by 715Pro transfectants was about 38% lower compared to wild-type transfectants. Binding of HL-60 cells to 715Pro transfectants was ~29% lower than to wild-type transfectants. This observation was confirmed by the presence of fewer platelet-monocyte aggregates (PMA) in the blood of healthy individuals and patients with angiographically proven atherosclerosis, carrying 715Pro P-selectin compared to individuals with wild-type P-selectin. We conclude that the 715Pro variant impairs terminal glycosylation of P-selectin in Golgi, leading to reduced amounts of mature P-selectin and subsequently less surface expression and secretion of P-selectin. The reduced surface expression of 715Pro P-selectin contributes to inefficient adhesion to HL-60 cells or monocytes.

An SNP in the Adiponectin Gene Is Associated with Decreased Serum Adiponectin Levels and Risk for Impaired Glucose Tolerance

Adiponectin is a plasma protein produced by the adipose tissue. Hypoadiponectinemia has been associated with insulin resistance and several components of the metabolic syndrome (MS): type 2 diabetes, obesity, and dyslipidemia. We investigated whether single nucleotide polymorphisms (SNPs) at positions 45 and 276 in the adiponectin gene were associated with features of the MS in 747 unrelated Spanish subjects. The G allele of SNP45 and the G/G genotype of SNP276 were associated with impaired glucose tolerance (p = 0.020 and 0.042, respectively). The G/G genotype for SNP276 was associated with lower serum adiponectin levels as compared with the G/T and T/T genotypes (G/G, 10.10 +/- 0.24 microg/mL; G/T, 10.98 +/- 0.32 microg/mL; T/T, 12.00 +/- 0.92 microg/mL; p = 0.015) even after adjustment for sex, age, BMI, waist-to-hip ratio, homeostasis model assessment index, and the degree of glucose tolerance (p = 0.040). We found a significant negative association of circulating adiponectin levels with waist-to-hip ratio (r = -0.42, p < 0.001), sagittal abdominal diameter (r = -0.24, p < 0.001), triglycerides (r = -0.32, p < 0.001), homeostasis model assessment index (r = -0.14, p = 0.001), and uric acid (r = -0.36, p < 0.001) and positive association with high-density lipoprotein-cholesterol (r = 0.41, p < 0.001). Our findings indicate that serum adiponectin levels are associated with several components of the MS. The SNP276 of the adiponectin gene may affect impaired glucose tolerance and hypoadiponectinemia.

An evolutionary history of the selectin gene cluster in humans

Molecules involved in leukocyte trafficking have a central role in the development of inflammatory and immune responses. We performed F(ST) analysis of the selectin cluster, as well as of SELPLG, ICAM1 and VCAM1. Peaks of significantly high population genetic differentiation were restricted to two regions in SELP and one in SELPLG. Resequencing data indicated that the region covering SELP exons 11-13 displays high nucleotide diversity in Africans and Europeans (CEU), and a high level of within-species diversity compared with inter-specific divergence. Analysis of inferred haplotypes revealed a complex phylogeny with two deeply separated clades that coalesce at ~3.5 million years (MY) plus a minor clade with a TMRCA (time to the most recent common ancestor) of ~2.2 MY. A splicing assay indicated no haplotype-specific effect on SELP exon 14 inclusion. These data are consistent with a model of multiallelic balancing selection; single-nucleotide polymorphism analysis indicated that the Val640Leu variant represents a likely selection target. In populations of Asian ancestry a distinct haplotype, possibly carrying regulatory variants, has been driven to high frequency by positive selection. No deviation from neutrality was observed for the SELPLG region. Resequencing of SELP in chimpanzees revealed a haplotype phylogeny with extremely deep basal branches, suggesting either long-standing balancing selection or ancestral population structure. Thus, SELP has experienced a complex selective history, possibly as a result of local adaptation. Variants in the gene have been associated with autoimmune and cardiovascular diseases. Association studies would benefit from both taking the complex SELP haplotype structure into account and from analysis of possible regulatory variants in the gene.

Association between PPAR-γ and RXR-α gene polymorphism and metabolic syndrome risk: a case-control study of a Chinese Han population

BACKGROUND AND AIMS

Polymorphisms in peroxisome proliferator activated receptor-γ (PPAR-γ) and retinoid X receptor-α (RXR-α) gene may alter metabolic syndrome (MetS) risks by increasing or decreasing the human adiponectin promoter activity in cells. To test this statement, three potentially functional SNPs of PPAR-γ and four SNPs of RXR-α with minor allele frequency (MAF) ≥0.05 in the Chinese Han population were identified from NCBI dbSNPs database to evaluate their associations with MetS.

METHODS

TaqMan assay was performed to test the genotypes in MetS patients (n = 901) and normal controls (n = 1009). Serum adiponectin concentration was measured by ELISA kit.

RESULTS

The variant genotypes rs2920502CG and CG/CC, rs4240711GG and AG/GG, rs4842194CC and CT/CC, rs3132291CT, CC and CT/CC were associated with MetS. Furthermore, in the haplotype of PPAR-γ gene, compared with the most common haplotype GC, haplotype CC was associated with an increased risk of MetS (crude p = 0.017). In the haplotype of RXR-α gene, haplotype GCGC was associated with a significant protective effect for MetS [adjusted p = 0.002, OR (95% CI) = 0.718 (0.585-0.882)] compared with the most common haplotype GTAT. After taking smoking, alcohol consumption and physical activity as environmental adjustment factors into the analysis, the result showed A1 A2 A4 A5 A6 A7 B1 (rs3856806, rs2920502, rs180128, rs1045570, rs3132291, rs4240711, rs4842194) was the best model (cross-validation consistency 10/10, p = 0.0107).

CONCLUSIONS

The present study suggested that the variant genotypes in PPAR-γ gene could increase the risk of MetS; however, genotypes in RXR-α gene could decrease the risk of MetS in a Chinese Han population.

Selectins and Associated Adhesion Proteins in Inflammatory disorders

Inflammation is defined as the normal response of living tissue to injury or infection. It is important to emphasize two components of this definition. First, that inflammation is a normal response and, as such, is expected to occur when tissue is damaged. Infact, if injured tissue does not exhibit signs of inflammation this would be considered abnormal and wounds and infections would never heal without inflammation. Secondly, inflammation occurs in living tissue, hence there is need for an adequate blood supply to the tissues in order to exhibit an inflammatory response. The inflammatory response may be triggered by mechanical injury, chemical toxins, and invasion by microorganisms, and hypersensitivity reactions. Three major events occur during the inflammatory response: the blood supply to the affected area is increased substantially, capillary permeability is increased, and leucocytes migrate from the capillary vessels into the surrounding interstitial spaces to the site of inflammation or injury. The inflammatory response represents a complex biological and biochemical process involving cells of the immune system and a plethora of biological mediators. Cell-to-cell communication molecules such as cytokines play an extremely important role in mediating the process of inflammation. Inflammation and platelet activation are critical phenomena in the setting of acute coronary syndromes. An extensive exposition of this complex phenomenon is beyond the scope of this article (Rankin 2004).

Association of common variants in JAK2 gene with reduced risk of metabolic syndrome and related disorders

BACKGROUND

Disturbances in leptin and insulin signaling pathways are related to obesity and metabolic syndrome (MS) with increased risk of diabetes and cardiovascular disease. Janus kinase 2 (JAK2) is a tyrosine kinase involved in the activation of mechanisms that mediate leptin and insulin actions. We conducted a population cross-sectional study to explore the association between two common variants in JAK2 gene and MS related traits in 724 Argentinean healthy male subjects.

METHODS

A total of 724 unrelated men aged 37.11 ± 10.91 yr were included in a cross-sectional study. Physical examination, anthropometric measurements and biochemical analysis were determined by a standardized protocol. rs7849191 and rs3780378 were genotyped. Analyses were done separately for each SNP and followed up by haplotype analysis.

RESULTS

rs7849191 and rs3780378 were both associated with reduced risk of MS [p = 0.005; OR (95%CI) = 0.52 (0.33-0.80) and p = 0.006; OR (95% CI) = 0.59 (0.40-0.86) respectively, assuming a dominant model]. rs3780378 T allele was associated with triglyceridemia values under 150 mg/dl [p = 0.007; OR (95%CI) = 0.610 (0.429-0.868)] and TT carriers showed lower triglycerides (p = 0.017), triglycerides/HDL-C ratio (p = 0.022) and lipid accumulation product (p = 0.007) compared to allele C carriers. The two-SNPs-haplotype analysis was consistent with single locus analysis.

CONCLUSIONS

It was found for the first time, significant associations of JAK2 common variants and related haplotypes with reduced risk of MS. These findings could be explained by the role of JAK2 in insulin and/or leptin signaling.

Single-nucleotide polymorphism of CD36 locus and obesity in European adolescents

CD36 is a membrane receptor with a wide variety of functions, including the regulation of energy metabolism, fat storage, and adipocyte differentiation. To assess the relationship between CD36 gene single-nucleotide polymorphisms (SNPs) and obesity in adolescents, we evaluated the relationship between CD36 SNPs and the risk of obesity in a case-control study composed of 307 obese (age = 15.0 +/- 1.1 years) and 339 normal-weight adolescents (age = 14.6 +/- 1.1 years). To validate the results, we assessed the relation between the same SNPs and percentage of body fat (BF%) and BMI in 1,151 European adolescents (age = 14.8 +/- 1.4 years). SNPs with a minor allele frequency >0.10 were selected to tag CD36. Genotyping was performed on an Illumina system. Four SNPs (rs3211867, rs3211883, rs3211908, and rs1527483) were associated with increased risk of obesity in the case-control study (odds ratio (OR) (95% confidence interval)): 1.96 (1.26-3.04], P = 0.003; 1.73 (1.16-2.59), P = 0.007; 2.42 (1.47-4.01), P = 0.0005 and 1.95 (1.25-3.05), P = 0.003, respectively). The same four SNPs were associated with higher BMI (P < 0.05) and BF% (P < 0.04) in the validation study. Further analyses identified a haplotype (frequency: 0.05) carrying the minor allele of these SNPs as being associated with obesity (OR: 2.28; P = 0.0008) in the case-control study and with excess adiposity (i.e., higher BF% (P = 0.03) and BMI (P = 0.04)) in the validation study. Our data suggest that genetic variability at the CD36 gene locus could be associated with body weight variability in European adolescents but these findings require replication.

Fibrinogen beta variants confer protection against coronary artery disease in a Greek case-control study

Background

Although plasma fibrinogen levels are related to cardiovascular risk, data regarding the role of fibrinogen genetic variation in myocardial infarction (MI) or coronary artery disease (CAD) etiology remain inconsistent. The purpose of the present study was to investigate the effect of fibrinogen A (FGA), fibrinogen B (FGB) and fibrinogen G (FGG) gene SNPs and haplotypes on susceptibility to CAD in a homogeneous Greek population.

Methods

We genotyped for rs2070022, rs2070016, rs2070006 in FGA gene, the rs7673587, rs1800789, rs1800790, rs1800788, rs1800787, rs4681 and rs4220 in FGB gene and for the rs1118823, rs1800792 and rs2066865 SNPs in FGG gene applying an arrayed primer extension-based genotyping method (APEX-2) in a sample of CAD patients (n = 305) and controls (n = 305). Logistic regression analysis was used to calculate odds ratios (ORs) and 95% confidence intervals (CIs), before and after adjustment for potential confounders.

Results

None of the FGA and FGG SNPs and FGA, FGB, FGG and FGA-FGG haplotypes was associated with disease occurrence after adjustment. Nevertheless, rs1800787 and rs1800789 SNPs in FGB gene seem to decrease the risk of CAD, even after adjustment for potential confounders (OR = 0.42, 95%CI: 0.19-0.90, p = 0.026 and OR = 0.44, 95%CI:0.21-0.94, p = 0.039, respectively).

Conclusions

FGA and FGG SNPs as well as FGA, FGB, FGG and FGA-FGG haplotypes do not seem to be important contributors to CAD occurrence in our sample. On the contrary, FGB rs1800787 and rs1800789 SNPs seem to confer protection to disease onset lowering the risk by about 50% in homozygotes for the minor alleles.

Detection of a large deletion in the P-selectin (SELP) gene

P-selectin is an adhesion molecule involved in the pathogenesis of inflammation, thrombosis, and oncogenesis. In this study of 51 polymorphisms in candidate genes for cardiovascular disease in 1561 individuals, we identified a new allelic variant of the SELP gene, g.18196_20704del, that determined the lack of genotyping for one polymorphism in one individual. It is a deletion of 2509 nucleotides which starts in intron 6 and ends in intron 8. Re-genotyping of 1023 apparent homozygotes indicated an overall allele frequency of 0.27%. The inclusion of this allelic variant in genetic association studies will avoid genotyping errors and marginally improve the sensitivity.

Peroxisome proliferator-activated receptor gamma polymorphisms and coronary heart disease

Single nucleotide polymorphisms (SNPs) in the peroxisome proliferator-activated receptor γ (PPARG) gene have been associated with cardiovascular risk factors, particularly obesity and diabetes. We assessed the relationship between 4 PPARG SNPs (C-681G, C-689T, Pro12Ala, and C1431T) and coronary heart disease (CHD) in the PRIME (249 cases/494 controls, only men) and ADVANCE (1,076 cases/805 controls, men or women) studies. In PRIME, homozygote individuals for the minor allele of the PPARG C-689T, Pro12Ala, and C1431T SNPs tended to have a higher risk of CHD than homozygote individuals for the frequent allele (adjusted OR [95% CI] = 3.43 [0.96–12.27], P = .058, 3.41 [0.95–12.22], P = .060 and 5.10 [0.99–26.37], P = .050, resp.). No such association could be detected in ADVANCE. Haplotype distributions were similar in cases and control in both studies. A meta-analysis on the Pro12Ala SNP, based on our data and 11 other published association studies (6,898 CHD cases/11,287 controls), revealed that there was no evidence for a significant association under the dominant model (OR = 0.99 [0.92–1.07], P = .82). However, there was a borderline association under the recessive model (OR = 1.29 [0.99–1.67], P = .06) that became significant when considering men only (OR = 1.73 [1.20–2.48], P = .003). In conclusion, the PPARG Ala12Ala genotype might be associated with a higher CHD risk in men but further confirmation studies are needed.

Vascular endothelial growth factor gene variation and the response to photodynamic therapy in age-related macular degeneration

PURPOSE

To evaluate the role of vascular endothelial growth factor (VEGF) gene polymorphisms in exudative age-related macular degeneration (AMD).

DESIGN

Retrospective, comparative case series.

PARTICIPANTS

Patients with recent exudative AMD (n = 162) and age-matched subjects without AMD (n = 85).

METHODS

Fluorescein angiography (FA), clinical examination, and single nucleotide polymorphism (SNP) genotyping.

MAIN OUTCOME MEASURES

The frequencies of 3 VEGF gene SNPs were analyzed, 1 at the promoter site (rs699947, A-->C) and 2 intronic SNPs (rs2146323, A-->C, and rs3025033, A-->G), in relation to the risk of AMD, to choroidal neovascular (CNV) lesion size and configuration, and to the anatomic response to photodynamic therapy (PDT). These SNPs were chosen to cover all the haploblocks of the VEGF gene. The 86 patients who had undergone PDT were classified as either PDT responders or PDT nonresponders based on the outcome of PDT after the last treatment session. For the PDT responders, the treating physician had deemed the lesion to be clinically dry and without leakage from CNV in FA at a visit scheduled at least 12 weeks after the last PDT treatment. For the PDT nonresponders, the PDT sessions had been discontinued by the treating retina specialist because of an apparently poor response and a still exudative lesion after several PDT sessions.

RESULTS

The presence of exudative AMD or lesion size or configuration was not associated with the SNPs studied here. The frequencies of the rs699947 were significantly different in PDT nonresponders and PDT responders. The AA, AC, and CC genotypes were 14%, 39%, and 46%, respectively, in PDT nonresponders, compared with 40%, 48%, and 12%, respectively, in the PDT responders (P = 0.0008). The corresponding frequencies for the rs2146323 AA, AC, and CC genotypes were 4%, 32%, and 64%, respectively, in nonresponders and 24%, 38%, and 38%, respectively, in responders (P = 0.0369). The genotypes of the rs3025033 SNP were distributed evenly between the responders and nonresponders.

CONCLUSIONS

The VEGF gene polymorphic SNPs at rs699947 and rs2146323 are strong determinants of the anatomic outcome after PDT, but the SNPs studied were not associated with the presence of exudative AMD or with the CNV lesion size or configuration.

FINANCIAL DISCLOSURE(S)

The author(s) have no proprietary or commercial interest in any materials discussed in this article.

Adhesion molecule polymorphisms and pulse wave velocity in American youth

BACKGROUND

Our research group recently reported that aorto-radial (radial) and aorto-dorsalis-pedis (foot) pulse wave velocity (PWV) as proxies of arterial stiffness are substantially heritable in healthy youth. This article aimed at uncovering the genetic contributions of adhesion molecules, key members in the inflammatory process, to PWV in these young individuals.

METHODS

Radial and foot PWV were noninvasively measured with applanation tonometry in 702 black and white subjects (42% blacks, mean age 17.7 +/- 3.3 years) from the Georgia Cardio vascular Twin Study. Eight functional polymorphisms from genes for E-selectin (SELE), P-selectin (SELP), intercellular adhesion molecules-1 (ICAM1), and vascular cell adhesion molecules-1 (VCAM1) were genotyped.

RESULTS

Youth with Ser290Asn or Asn290Asn genotype (SELP) compared to those with Ser290Ser had an increase in both radial and foot PWV (6.61 +/- 0.07 vs. 6.41 +/- 0.05 m/s, p = .026; 7.22 +/- 0.05 vs. 7.04 +/- 0.04 m/s, p = .007). TT homozygotes of rs2244529 (SELP) had higher foot PWV (7.28 +/- 0.07 vs. 7.06 +/- 0.03 m/s, p = .002) than CT heterozygotes and CC homozygotes. There appeared to be a decrease in foot PWV in youth with the 241Arg allele (ICAM1) as compared to those without (6.96 +/- 0.08 vs. 7.14 +/- 0.03 m/s, p = .005). For the Asp693Asp (C to T) polymorphism (VCAM1), CC genotype had higher foot PWV than CT and TT genotypes (7.18 +/- 0.04 vs. 6.95 +/- 0.06 m/s, p < .0001). There was an epistatic interaction between Ser290Asn, Gly241Arg, and Asp693Asp on foot PWV (p = .017), explaining 3.6% variance of the foot PWV.

CONCLUSION

Genetic variation of adhesion molecules may be implicated in the development of arterial stiffness. Screening for adhesion molecule polymorphisms may help identify high-risk youth.

Haplotype associations with quantitative traits in the presence of complex multilocus and heterogeneous effects

In genetic mapping of complex traits, scored haplotypes are likely to represent only a subset of all causal polymorphisms. At the extreme of this scenario, observed polymorphisms are not themselves functional, and only linked to causal ones via linkage disequilibrium (LD). We will demonstrate that due to such incomplete knowledge regarding the underlying genetic mechanism, the variance of a trait may become different between the scored haplotypes. Thus, unequal variances between haplotypes may be indicative of additional functional polymorphisms affecting the trait. Methods accounting for such haplotype-specific variance may also provide an increased power to detect complex associations. We suggest ways to estimate and test these haplotypic variance contrasts, and incorporate them into the haplotypic tests for association. We further extend this approach to data with unknown gametic phase via likelihood-based simultaneous estimation of haplotypic effects and their frequencies. We find our approach to provide additional power, especially under the following types of models: (a) where scored and unobserved variants are epistatically interacting with each other; and (b) under heterogeneity models, where multiple unobserved mutations are linked to non-functional observed polymorphisms via LD. An illustrative example of usefulness of the method is discussed, utilizing analysis of multilocus effects within the catechol-O-methyltransferase gene.

An age effect on the association of common variants of ACE with Alzheimer's disease

It is now well established that vascular risk factors are associated with cognitive performances. The renin-angiotensin system (RAS) components, major determinants of the cardiovascular system, are expressed in the brain and were shown to play a role on amyloid metabolism, learning and memory. The angiotensin-converting enzyme (ACE), a pivotal RAS protein, is encoded by a huge gene containing many variants, one of them, the I/D variant (rs1799752), being associated with Alzheimer's disease (AD). Other variants, such as SNPs rs4291A>T located -240bp from the initiation codon, and rs4343G>A encoding a silent mutation in exon 16, were inconsistently associated with the risk of AD. In a case-control study including 376 late-onset AD patients and 444 control subjects, we showed a statistically significant effect on the risk of AD of two variants (rs4343 and rs1799752) and of the haplotype ATI (rs4343/rs4291/rs1799752) in subjects aged 73 years and above.

Molecular and functional characterization of polymorphisms in the secreted phospholipase A2 group X gene: relevance to coronary artery disease

Among secreted phospholipases A2 (sPLA2s), human group X sPLA2 (hGX sPLA2) is emerging as a novel attractive therapeutic target due to its implication in inflammatory diseases. To elucidate whether hGX sPLA2 plays a causative role in coronary artery disease (CAD), we screened the human PLA2G10 gene to identify polymorphisms and possible associations with CAD end-points in a prospective study, AtheroGene. We identified eight polymorphisms, among which, one non-synonymous polymorphism R38C in the propeptide region of the sPLA2. The T-512C polymorphism located in the 5' untranslated region was associated with a decreased risk of recurrent cardiovascular events during follow-up. The functional analysis of the R38C polymorphism showed that it leads to a profound change in expression and activity of hGX sPLA2, although there was no detectable impact on CAD risk. Due to the potential role of hGX sPLA2 in inflammatory processes, these polymorphisms should be investigated in other inflammatory diseases.

SELP and SELPLG genetic variation is associated with cell surface measures of SELP and SELPLG: the Atherosclerosis Risk in Communities Carotid MRI Study

BACKGROUND

P-selectin (SELP) and its ligand, P-selectin glycoprotein ligand 1 (SELPLG), play key roles in both the inflammatory response and the atherosclerotic process. Previous studies have shown genetic variation in the SELP gene [selectin P (granule membrane protein 140 kDa, antigen CD62)] to be associated with plasma SELP concentrations; however, the major biological function of SELP (and SELPLG) is at the cell surface. We therefore investigated the association of SELP polymorphisms with platelet SELP measures and polymorphisms in the SELPLG gene (selectin P ligand) with lymphocyte, granulocyte, and monocyte SELPLG measures among 1870 participants in the Atherosclerosis Risk in Communities (ARIC) Carotid MRI Study.

METHODS

Whole-blood flow cytometry was used to analyze leukocyte and platelet markers in the ARIC Carotid MRI Study. The allele frequencies for the SELP and SELPLG polymorphisms of whites and African Americans were markedly different; therefore, all analyses were race specific.

RESULTS

SELP T715P was significantly associated with lower values for platelet SELP measures in whites (P = 0.0001), whereas SELP N562D was significantly associated with higher values for SELP measures in African Americans (P = 0.02). SELPLG M62I was significantly associated with lower granulocyte and monocyte SELPLG measures in African Americans (P = 0.003 and P = 0.0002, respectively) and with lower lymphocyte SELPLG measures in whites (P = 0.01).

CONCLUSIONS

Specific SELP and SELPLG polymorphisms were associated with cell surface measures of SELP and SELPLG in both whites and African Americans in the ARIC Carotid MRI Study. To our knowledge, this study is the first to examine the association of SELP and SELPLG genetic variation with measures of cell surface SELP and SELPLG.

Association of ABCB1 gene polymorphisms with plasma lipid and apolipoprotein concentrations in the STANISLAS cohort

BACKGROUND

While involvement of ABCB1 is well known in drug transport, its metabolite transport role is not so well understood. Like other ABC transporters, ABCB1 might be implicated in cholesterol homeostasis and ABCB1 polymorphisms which are responsible for drug resistance might affect lipid homeostasis. Our objective was thus to investigate the implication of ABCB1 polymorphisms and haplotypes in the genetic variability of lipid constituents in healthy people.

METHODS

T-129C, G-1A, A61G, G1199A, C1236T, T-76A, G2677T/A and C3435T polymorphisms were genotyped in 371 supposed healthy individuals from the STANISLAS cohort. Each polymorphism was tested with plasma concentrations of total cholesterol, HDL and LDL cholesterol, triglycerides and apolipoproteins A1, B, C3 and E.

RESULTS

After adjustment for covariates, carriers of at least one 3435T allele had a significant higher level of apolipoprotein A1 (p = 0.005). In addition, significant correlations were observed in a sex-dependent manner. Women carrying either T-76 or 1236T allele (tendency with G-1 and 2677T/A) had lower total cholesterol (p < or = 0.01) and apolipoprotein B (T-76 exclusively, p=0.002). Haplotypes analysis was not more informative than the single polymorphisms except G2677T/A-C3435T haplotypes for apolipoprotein A1 concentration.

CONCLUSION

ABCB1 polymorphisms contribute to the genetic variability of plasma values of lipids and lipoproteins in healthy people.

The 9p21 susceptibility locus for coronary artery disease and the severity of coronary atherosclerosis

Background

Case-control Genome-Wide Association Studies (GWAS) have identified single nucleotide polymorphisms (SNPs) at the 9p21 locus as risk factors for coronary artery disease (CAD). The locus does not contain a clear candidate gene. Hence, the results of GWAS have raised an intense interest in delineating the basis for the observed association. We analyzed association of 4 SNPs at the 9p21 locus with the severity and progression of coronary atherosclerosis, as determined by serial quantitative coronary angiograms (QCA) in the well-characterized Lipoprotein Coronary Atherosclerosis Study (LCAS) population. The LCAS is a randomized placebo-control longitudinal follow-up study in patients with CAD conducted to test the effects of fluvastatin on progression or regression of coronary atherosclerosis.

Methods

Extensive plasma lipid levels were measured at the baseline and 2 1/2 years after randomization. Likewise serial QCA was performed at the baseline and upon completion of the study. We genotyped the population for 4 SNPs, previously identified as the susceptibility SNPs for CAD in GWAS, using fluorogenic 5' nuclease assays. We reconstructed the haplotypes using Phase 2, analyzed SNP and haplotype effects using the Thesias software as well as by the conventional statistical methods.

Results

Only Caucasians were included since they comprised 90% of the study population (332/371 with available DNA sample). The 4 SNPs at the 9p21 locus were in tight linkage disequilibrium, leading to 3 common haplotypes in the LCAS population. We found no significant association between quantitative indices of severity of coronary atherosclerosis, such as minimal lumen diameter and number of coronary lesions or occlusions and the 9p21 SNPs and haplotypes. Likewise, there was no association between quantitative indices of progression of coronary atherosclerosis and the SNPs or haplotypes. Similarly, we found no significant SNP or haplotype effect on severity and progression of coronary atherosclerosis.

Conclusion

We conclude the 4 SNPs at the 9p21 locus analyzed in this study do not impart major effects on the severity or progression of coronary atherosclerosis. The effect size may be very modest or the observed association of the CAD with SNPs at the 9p21 locus in the case-control GWAS reflect involvement of vascular mechanisms not directly related to the severity or progression of coronary atherosclerosis.

P-selectin gene polymorphisms and risk of coronary heart disease among Tunisians

P-selectin plays a key role in inflammation and atherosclerosis, and polymorphic variants of P-selectin were implicated in the pathogenesis of atherosclerotic and inflammatory changes, including coronary heart disease (CHD) in many ethnic groups. We investigated the contribution of P-selectin promoter (-2123C/G, -1969G/A) and exon (Ser290Asn, Asn562Asp, Thr715Pro) polymorphisms to CHD genetic susceptibility among 298 Tunisian CHD patients and 339 controls. Minor allele and genotype frequencies of the five P-selectin SNPs were comparable between patients and controls, except for -2123G/G genotype which was more frequent in cases. The 715Pro allele was present at lower frequency in Tunisians than in Europeans, and was not protective of CHD. Linkage disequilibrium was seen between -1969G/A, and both Ser290Asn and Asn562Asp. Five-loci haplotype analysis did not identify any CHD-protective or CHD-susceptible haplotypes. To our knowledge, this was the first case-control study to be performed on an Arab/North-African population, and demonstrates that none of the five P-selectin polymorphisms investigated influence CHD susceptibility in Tunisian Arabs.

ANGPTL4 E40K and T266M: effects on plasma triglyceride and HDL levels, postprandial responses, and CHD risk

BACKGROUND

Angiopoietin-like 4 is a dual-function protein: an inhibitor of LPL, influencing plasma triglycerides (TGs), with angiogenic properties. We examined the association of common ANGPTL4 variants with CHD traits and risk in 5 studies (13,527 individuals).

METHODS AND RESULTS

The effects on plasma lipids of 6 tagging SNPs and the recently identified E40K were examined in a study of 2772 men. Only T266M (rs1044250, MAF=30%) and E40K (MAF=2%) were significantly associated with TG-lowering (-10.4%, P<0.004 and -20.4%, P<0.0001), respectively. T266M no longer showed significant associations when K40 carriers (K40+) were excluded (P=0.2). Combining data from 5 studies confirmed the TG-lowering effect of K40+ (weighted mean difference: -0.12 [95% CI -0.18, -0.05] mmol/L TG P=0.0001). Surprisingly, in the 3 prospective studies, the combined OR for CHD was 1.48 (1.11 to 1.96, P=0.007), independent of TG. In individuals with a paternal history of MI (n=332) T266M, but not E40K, showed effects on postprandial AUC TG and glucose (P=0.009 and P=0.017, respectively) compared to controls (n=370).

CONCLUSIONS

Although associated with an atheroprotective lipid profile, E40K was associated with increased CHD risk, suggesting Angptl4 influences parameters beyond lipid levels. T266M showed effects only under conditions of postprandial stress. The functionality of these potential "loss-of-function" variants needs validation.

The APOA5 Trp19 allele is associated with metabolic syndrome via its association with plasma triglycerides

BACKGROUND

The goal of the present study was to assess the effect of genetic variability at the APOA5/A4/C3/A1 cluster locus on the risk of metabolic syndrome.

METHODS

The APOA5 Ser19Trp, APOA5 -12,238T>C, APOA4 Thr347Ser, APOC3 -482C>T and APOC3 3238C>G (SstI) polymorphisms were analyzed in a representative population sample of 3138 men and women from France, including 932 individuals with metabolic syndrome and 2206 without metabolic syndrome, as defined by the NCEP criteria.

RESULTS

Compared with homozygotes for the common allele, the odds ratio (OR) [95% CI] for metabolic syndrome was 1.30 [1.03-1.66] (p = 0.03) for APOA5 Trp19 carriers, 0.81 [0.69-0.95] (p = 0.01) for APOA5 -12,238C carriers and 0.84 [0.70-0.99] (p = 0.04) for APOA4 Ser347 carriers. Adjustment for plasma triglycerides, (but not for waist girth, HDL, blood pressure or glycemia - the other components of metabolic syndrome) abolished these associations and suggests that triglyceride levels explain the association with metabolic syndrome. There was no association between the APOC3 -482C>T or APOC3 3238C>G polymorphisms and metabolic syndrome. The decreased risk of metabolic syndrome observed in APOA5 -12,238C and APOA4 Ser347 carriers merely reflected the fact that the APOA5 Trp19 allele was in negative linkage disequilibrium with the common alleles of APOA5 -12,238T>C and APOA4 Thr347Ser polymorphisms.

CONCLUSION

The APOA5 Trp19 allele increased susceptibility to metabolic syndrome via its impact on plasma triglyceride levels.

Molecular genetics of myocardial infarction

Myocardial infarction (MI) is an important clinical problem because of its large contribution to mortality. The main causal and treatable risk factors for MI include hypertension, hypercholesterolemia or dyslipidemia, diabetes mellitus, and smoking. In addition to these risk factors, recent studies have shown the importance of genetic factors and interactions between multiple genes and environmental factors. Disease prevention is an important strategy for reducing the overall burden of MI, with the identification of markers for disease risk being key both for risk prediction and for potential intervention to lower the chance of future events. Although genetic linkage analyses of families and sib-pairs as well as candidate gene and genome-wide association studies have implicated several loci and candidate genes in predisposition to coronary heart disease (CHD) or MI, the genes that contribute to genetic susceptibility to these conditions remain to be identified definitively. In this review, we summarize both candidate loci for CHD or MI identified by linkage analyses and candidate genes examined by association studies. We also review in more detail studies that have revealed the association with MI or CHD of polymorphisms in MTHFR, LPL, and APOE by the candidate gene approach and those in LTA and at chromosomal region 9p21.3 by genome-wide scans. Such studies may provide insight into the function of implicated genes as well as into the role of genetic factors in the development of CHD and MI.

Sialic acids in human health and disease

The surfaces of all vertebrate cells are decorated with a dense and complex array of sugar chains, which are mostly attached to proteins and lipids. Most soluble secreted proteins are also similarly decorated with such glycans. Sialic acids are a diverse family of sugar units with a nine-carbon backbone that are typically found attached to the outermost ends of these chains. Given their location and ubiquitous distribution, sialic acids can mediate or modulate a wide variety of physiological and pathological processes. This review considers some examples of their established and newly emerging roles in aspects of human physiology and disease.

Primary and secondary capture of platelets onto inflamed femoral artery endothelium is dependent on P-selectin and PSGL-1

Platelets constitute a key role in vascular injuries, however, the detailed mechanisms behind platelet-endothelial cell and platelet-leukocyte interactions in the femoral artery are not yet fully elucidated. We used intravital fluorescence microscopy of the femoral artery in C57BL/6 mice to study primary and secondary capture of platelets onto endothelial cells as well as onto adherent platelets and leukocytes in vivo. By use of monoclonal antibodies, the role of P-selectin and P-selectin glycoprotein ligand 1 (PSGL-1) in these adhesive interactions in mice exposed to endotoxin was determined. Intravenous injection of endotoxin significantly increased gene expression of P-selectin as well as platelet tethering, rolling and adhesion in the femoral artery. Pretreatment with the anti-PSGL-1 antibody decreased platelet tethering by 85%, platelet rolling by 88% and platelet adhesion by 96%. Immunoneutralization of P-selectin reduced platelet tethering by 91%, platelet rolling by 98%, and platelet adhesion by 97%. In addition, inhibition of P-selectin and PSGL-1 completely abolished secondary capture of platelets onto adherent platelets and leukocytes. Our data show that P-selectin and PSGL-1 mediate early interactions between platelets and other cells, including endothelial cells and leukocytes, in inflamed arteries. These novel results suggest that interference with P-selectin and PSGL-1 may be a useful target in strategies aiming to protect the vascular wall during arterial inflammation.

Soluble P-selectin, SELP polymorphisms, and atherosclerotic risk in European-American and African-African young adults: the Coronary Artery Risk Development in Young Adults (CARDIA) Study

OBJECTIVE

To characterize the genetic and clinical correlates of soluble P-selectin, and the relationship of P-selectin to atherosclerotic risk, in young European-American (EA) and African-American (AA) adults.

METHODS AND RESULTS

We assessed the interrelationships between 25 common SELP polymorphisms, soluble P-selectin, and atherosclerotic risk in 1222 EA and 1072 AA from the longitudinal population-based CARDIA study. Male sex, smoking, blood pressure, and metabolic status were strong cross-sectional correlates of soluble P-selectin among CARDIA subjects aged 33 to 45 years, explaining 13% of the variance. Among EAs, higher soluble P-selectin predicted carotid intima-media thickness (IMT) measured 5 years later, even after accounting for traditional risk factors. Common SELP nucleotide sequence variants explained 11% and 5% of the interindividual variation in soluble P-selectin levels in EAs and AAs, respectively. Four distinct variants contributed to P-selectin phenotype in EAs, including a polymorphism of the 5' SELP haplotype block associated with carotid IMT. Half of the phenotypic variation attributable to SELP in EAs could be explained by the Thr715Pro polymorphism, whereas Val599Leu was more strongly associated with soluble P-selectin among AAs.

CONCLUSIONS

Common SELP polymorphisms were associated with soluble P-selectin and carotid IMT in young adults, but the patterns of association differed between EAs and AAs. These results support the role of P-selectin in the preclinical stages of atherosclerosis.

P-selectin polymorphisms' influences on P-selectin serum concentrations and on their familial correlation: the STANISLAS family study

BACKGROUND

P-selectin is an adhesion molecule known to be involved in the pathogenesis of several diseases through its major role in the initial phase of leukocytes recruitment during inflammation. However, genetic characterization of soluble P-selectin remains unclear.

OBJECTIVES

In the STANISLAS cohort, we study the familial correlations of P-selectin levels and investigate the association of six P-selectin polymorphisms (C-2123G, A-1969G, S290N, N562D, V599L and T715P) and cardiovascular risk factors with P-selectin concentrations.

PATIENTS/METHODS

Full phenotypic and genotypic information was available for 136 healthy families composed of both natural parents and at least one child (boys, n = 125; and girls, n = 139) aged more than 4 years.

RESULTS

While no correlation was observed between spouses, family correlations of P-selectin concentrations were highly significant for sibling (0.50 +/- 0.12, P < 10(-3)) and child-parent pairs (0.42 +/- 0.04, P < 10(-3)). P-selectin haplotypes explained about 25% of the variability of P-selectin concentrations, this effect being mainly due to the additive effects of two polymorphisms, V599L and T715P. After adjusting for the effect of the P-selectin polymorphisms, the sibling and child-parent correlations decreased to (0.39 +/- 0.08, P < 10(-4)) and (0.32 +/- 0.06, P < 10(-4)), respectively.

CONCLUSIONS

In the present study, we showed that two P-selectin polymorphisms, V599L and T715P, explained about 25% of the variability of P-selectin concentrations and accounted for about 40% of their family resemblance. These results would suggest a genetic influence on P-selectin concentrations beyond the contribution of the P-selectin gene.

Repeated replication and a prospective meta-analysis of the association between chromosome 9p21.3 and coronary artery disease

BACKGROUND

Recently, genome-wide association studies identified variants on chromosome 9p21.3 as affecting the risk of coronary artery disease (CAD). We investigated the association of this locus with CAD in 7 case-control studies and undertook a meta-analysis.

METHODS AND RESULTS

A single-nucleotide polymorphism (SNP), rs1333049, representing the 9p21.3 locus, was genotyped in 7 case-control studies involving a total of 4645 patients with myocardial infarction or CAD and 5177 controls. The mode of inheritance was determined. In addition, in 5 of the 7 studies, we genotyped 3 additional SNPs to assess a risk-associated haplotype (ACAC). Finally, a meta-analysis of the present data and previously published samples was conducted. A limited fine mapping of the locus was performed. The risk allele (C) of the lead SNP, rs1333049, was uniformly associated with CAD in each study (P<0.05). In a pooled analysis, the odds ratio per copy of the risk allele was 1.29 (95% confidence interval, 1.22 to 1.37; P=0.0001). Haplotype analysis further suggested that this effect was not homogeneous across the haplotypic background (test for interaction, P=0.0079). An autosomal-additive mode of inheritance best explained the underlying association. The meta-analysis of the rs1333049 SNP in 12,004 cases and 28,949 controls increased the overall level of evidence for association with CAD to P=6.04x10(-10) (odds ratio, 1.24; 95% confidence interval, 1.20 to 1.29). Genotyping of 31 additional SNPs in the region identified several with a highly significant association with CAD, but none had predictive information beyond that of the rs1333049 SNP.

CONCLUSIONS

This broad replication provides unprecedented evidence for association between genetic variants at chromosome 9p21.3 and risk of CAD.