Association of the Lewis genotype with cardiovascular risk factors and subclinical carotid atherosclerosis: the Atherosclerosis Risk in Communities (ARIC) study

Estimation of Lewis Blood Group Status by Fluorescence Melting Curve Analysis in Simultaneous Genotyping of c.385A>T and Fusion Gene in FUT2 and c.59T>G and c.314C>T in FUT3

Lewis blood group status is determined by two fucosyltransferase activities: those of FUT2-encoded fucosyltransferase (Se enzyme) and FUT3-encoded fucosyltransferase (Le enzyme). In Japanese populations, c.385A>T in FUT2 and a fusion gene between FUT2 and its pseudogene SEC1P are the cause of most Se enzyme-deficient alleles (Se^w and se^fus), and c.59T>G and c.314C>T in FUT3 are tag SNPs for almost all nonfunctional FUT3 alleles (le⁵⁹, le^59,508, le^59,1067, and le^202,314). In this study, we first conducted a single-probe fluorescence melting curve analysis (FMCA) to determine c.385A>T and se^fus using a pair of primers that collectively amplify FUT2, se^fus, and SEC1P. Then, to estimate Lewis blood group status, a triplex FMCA was performed with a c.385A>T and se^fus assay system by adding primers and probes to detect c.59T>G and c.314C>T in FUT3. We also validated these methods by analyzing the genotypes of 96 selected Japanese people whose FUT2 and FUT3 genotypes were already determined. The single-probe FMCA was able to identify six genotype combinations: 385A/A, 385T/T, se^fus/se^fus, 385A/T, 385A/se^fus, and 385T/se^fus. In addition, the triplex FMCA successfully identified both FUT2 and FUT3 genotypes, although the resolutions of the analysis of c.385A>T and se^fus were somewhat reduced compared to that of the analysis of FUT2 alone. The estimation of the secretor status and Lewis blood group status using the form of FMCA used in this study may be useful for large-scale association studies in Japanese populations.

Fluorescence Melting Curve Analysis for Concurrent Genotyping of Three Tag SNPs in FUT3

The synthesis of Lewis blood group antigens is governed by two fucosyltransferase genes, FUT2 and FUT3. Evidence is accumulating to suggest that functional polymorphisms of FUT2 and FUT3 are associated with a variety of clinical conditions. Fluorescence melting curve analysis (FMCA), using three different dual-labeled probes for concurrent genotyping of three single nucleotide polymorphisms (SNPs) of FUT3, c.59T>G, c.314C>T, and c.484G>A for Lewis-negative allele inference, was developed and validated using Ghanaian and Caucasian subjects. Although two other SNPs, c.55G>A, and c.61C>T, are located in the probe sequence for c.59T>G, it seems feasible to detect these two SNPs along with c.59T>G. The results obtained by probe-based FMCA were in perfect accordance with those obtained by Sanger sequencing for 106 Ghanaians and 100 Caucasians. The present method is useful and reliable for estimating Lewis-negative alleles on a relatively large scale.

Rapid genotyping of 508G>A (rs3745635) and 1067T>A (rs3894326) of FUT3 by a duplex Eprobe-mediated melting curve analysis

BACKGROUND AND OBJECTIVES

Lewis histo-blood group phenotypes are regulated by the action of FUT3-encoded α(1,3/1,4)fucosyltransferase and FUT2-encoded α(1,2)fucosyltransferase. Since Lewis phenotypes are suggested to be associated with various clinical conditions, a method for large-scale FUT3 genotyping is desirable. In worldwide populations, 508G>A and 1067T>A of FUT3 are two of three common causal single nucleotide polymorphisms for Lewis-negative alleles.

MATERIALS AND METHODS

We developed a duplex Eprobe-mediated melting curve analysis for genotyping 508G>A and 1067T>A simultaneously and applied this method to 106 Ghanaian and 140 Japanese subjects.

RESULTS

The results of both 508G>A and 1067T>A genotyping by duplex Eprobe-mediated melting curve analysis were completely in agreement with the results of a DNA sequence analysis in 106 Ghanaians and polymerase chain reaction-restriction fragment length polymorphism analysis in 140 Japanese subjects.

CONCLUSION

The present duplex Eprobe-mediated melting curve analysis is valid and credible for large-scale estimation of Lewis-negative alleles.

Assessment of Lewis negative phenotype as a risk factor for multivessel disease in patients with acute coronary syndrome

INTRODUCTION

Acute coronary syndrome is a manifestation of coronary artery disease caused by decreased blood flow to the heart musculature resulting in ischaemia and infarction of the heart. The Lewis (Le) blood group system comprise mainly Lewis a & b antigens which are secreted in plasma and are expressed on red cells, platelets and endothelium. This study assesses the risk of multivessel disease in acute coronary patients with lewis negative (a- b-) phenotype.

MATERIALS AND METHODS

The study included 183 patients diagnosed with acute coronary syndrome and who underwent coronary angiography to detect stenosis of the coronary vessels. The severity of the disease was classified based upon the number of vessels stenosed and their blood sample was phenotyped for Lewis antigens. The patients' risk factors, GRACE score and management were included for the study and multivariate logistic regression was carried out for analysis.

RESULTS

The prevalence of Lewis (a- b-) was 27.4% and there was a significant association with multivessel disease (P<0.05). However, there was no association of lewis (a- b-) with any of the risk factors causing coronary disease. The adjusted odds ratio of triple vessel disease in lewis (a- b-) was 2.6, female gender was 0.6 and patients with diabetes mellitus was 3.1, respectively. The GRACE score showed a significant association with ABO blood group (P<0.05) but not with lewis (a- b-).

DISCUSSION

Lewis negative patients are more likely to develop triple vessel disease compared to other lewis blood groups. This warrants further studies to investigate the link between lewis system and atherothrombosis.

Estimation of Lewis-negative alleles by high-resolution melting analysis of three tag SNPs of FUT3

BACKGROUND AND OBJECTIVES

The expression of type 1 chain Lewis blood group antigens is regulated by secretor-type α(1,2)fucosyltransferase, encoded by FUT2, and Lewis α(1,3/1,4)fucosyltransferase, encoded by FUT3. Accumulating evidence has linked Lewis phenotypes or genotypes to various clinical conditions. Thus, in addition to FUT2, large-scale FUT3 genotyping is important. Because FUT3 has two paralogous genes (FUT5 and FUT6) with high DNA sequence similarity, we should select the polymerase chain reaction (PCR) primers carefully for FUT3 genotyping. Previously, we suggested that 13G>A (rs28362458), 59T>G (rs28362459) and 202T>C (rs812936) could be selected as tag single nucleotide polymorphisms (SNPs) for detection of Lewis-negative alleles (le).

MATERIALS AND METHODS

In this study, three high-resolution melting (HRM) analyses for genotyping these SNPs were developed and applied for 140 Japanese, eight Ghanaians and four Sinhalese subjects.

RESULTS

Each of three genotypes of 13G>A (G/G, G/A, A/A), 59T>G (T/T, T/G, G/G) and 202T>C (T/T, T/C, C/C) was discriminated clearly. Although we need to be careful in interpretation of results due to SNPs other than the 59T>G in the amplicon, the results of 59T>G genotyping were in full agreement with the results by a previous PCR-restriction fragment length polymorphism analysis in 140 Japanese. In addition, three heterozygotes of 202C substitution were identified, and no one having a 13A substitution was found in 140 Japanese.

CONCLUSION

The present HRM analyses are useful and reliable methods for large-scale estimation of le alleles.

Lewis blood group phenotype vis-a-vis biochemical and physiological parameters of coronary artery disease: A study in North Indian population

BACKGROUND:

Many studies have proposed the lack of Lewis antigen as a marker for coronary artery disease (CAD); on the contrary, some of the studies found no association in this regard. This study aims to assess the association of the expression of Lewis antigen as an independent risk factor for CAD separately in males and females.

MATERIALS AND METHODS:

In this cross-sectional observational study, patients with angiographically proven CAD were taken as test group, and angiographically, negative patients were included as a control group. The individuals were examined for established CAD risk factor and Lewis antigen expression on red cell. Red cell Lewis phenotyping was done using microcolumn gel agglutination technology. Statistical tests were applied to see the association between lack of Lewis antigen expression and CAD.

RESULTS:

Of these 232 patients included in the study, 161 patients had more than 50% luminal stenosis in a major epicardial artery on coronary angiography (Test Group), and 71 were normal on angiography (Control Group). When males and females were considered together, there was an increased frequency of Lewis-negative phenotype among the angiography-positive group (26.7%) as compared to angiography normal control group (16.9 %), though was not statistically significant (P = 0.19). When males and females were segregated in multivariate analysis, Le (a-b-) females had a higher incidence of CAD (P = 0.03) with the odds ratio of 4.97, though an association was not found significant in males (P = 0.71).

CONCLUSION:

The association between Lewis phenotypes and CAD was not significant in males and in among the overall study population, but this association was statistically significant in females. Further studies based on a larger sample size may substantiate as well as delineate the possible hypotheses.

Fucosyltransferase Gene Polymorphisms and Lewisb-Negative Status Are Frequent in Swedish Newborns, With Implications for Infectious Disease Susceptibility and Personalized Medicine

BACKGROUND

Single-nucleotide polymorphisms (SNPs) in the fucosyltransferase genes FUT2 and FUT3 have been associated with susceptibility to various infectious and inflammatory disorders. FUT variations influence the expression of human histo-blood group antigens (HBGAs) (H-type 1 and Lewis), which are highly expressed in the gut and play an important role in microbial attachment, metabolism, colonization, and shaping of the microbiome. In particular, FUT polymorphisms confer susceptibility to specific rotavirus and norovirus genotypes, which has important global health implications.

METHODS

We designed a genotyping method using a nested polymerase chain reaction approach to determine the frequency of SNPs in FUT2 and FUT3, thereby inferring the prevalence of Lewisb-positive, Lewisb-negative, secretor, and nonsecretor phenotypes in 520 Swedish newborns.

RESULTS

There was an increased frequency of homozygotes for the minor allele for 1 SNP in FUT2 and 4 SNPs in FUT3. Overall, 37.3% of newborns were found to have Lewis b negative phenotypes (Le (a+b-) or Le (a-b-). Using our new, sensitive genotyping method, we were able to genetically define the Le (a-b-) individuals based on their secretor status and found that the frequency of Lewis b negative newborns in our cohort was 28%.

CONCLUSIONS

Given the high frequency of fucosyltransferase polymorphisms observed in our newborn cohort and the implications for disease susceptibility, FUT genotyping might play a future role in personalized health care, including recommendations for disease screening, therapy, and vaccination.

Abnormal blood rheology and chronic low grade inflammation: possible risk factors for accelerated atherosclerosis and coronary artery disease in Lewis negative subjects

OBJECTIVE

To test the hypothesis that abnormal hemorheology and chronic low-grade inflammation are more prevalent in Lewis negative individuals, possibly contributing to premature atherosclerosis.

METHODS AND RESULTS

We enrolled 223 healthy subjects (154 females, mean age: 64yrs). Conventional risk factors, markers of inflammation and hemorheological profiles were measured; Lewis blood group was determined by serology. Conventional risk factors (age, gender, BMI, blood pressure, lipid profile, smoking habit) did not differ among Lewis phenotypes. However, markers of inflammation (WBC, hs-CRP, ESR) were significantly elevated and rheological parameters (RBC aggregation, plasma viscosity) were abnormal in Lewis negative subjects, especially when compared to the Le(a-b+) group.

CONCLUSIONS

With a prevalence of 33% in select populations, our data support the hypothesis that Le(a-b-) represents a pro-inflammatory phenotype that may contribute to the elevated cardiovascular risk in this group.

The influence of maternal Lewis, Secretor and ABO(H) blood groups on fetal growth restriction

BACKGROUND

Fetal growth restriction (FGR) is associated with thrombosis of the placenta and an increased risk of subsequent vascular disease in the mother and fetus. The products of interactions between ABO(H), Lewis and Secretor genes are also associated with thrombosis and vascular disease risk.

OBJECTIVES/METHODS

A prospective case-control study of mothers with a severe FGR pregnancy (cases, n = 128; controls, n = 288) was performed to determine whether FGR is associated with particular maternal blood groups.

RESULTS

No association with ABO(H) status was observed, but FGR was more common in maternal secretors (odds ratio [OR] 1.70, 95% confidence interval [CI] 1.08-2.69) and consequently in those mothers expressing Le(b) on their red cells (OR 1.80, 95% CI 1.15-2.83), with a reduced risk in non-secretors and those expressing Le(a). Given the association between blood groups and both activated protein C resistance (APCR) and von Willebrand factor (VWF) levels, post hoc pilot studies on first-trimester APCR and VWF antigen levels and blood group genotypes were performed. No relationship with Lewis or Secretor was observed. Despite this, lower first-trimester VWF levels were observed in pregnancies subsequently complicated by FGR.

CONCLUSIONS

 This is the first study reporting a relationship between maternal Secretor/Lewis status and FGR. A link between blood groups and FGR is plausible, as both are associated with cardiovascular disease. We observed no relationship between Lewis/Secretor status and VWF or APCR, but this should be confirmed in a larger study. Thus, the mechanism whereby Secretor and/or Lewis influences FGR is unknown.

Gender differences in genetic risk profiles for cardiovascular disease

Background

Cardiovascular disease (CVD) incidence, complications and burden differ markedly between women and men. Although there is variation in the distribution of lifestyle factors between the genders, they do not fully explain the differences in CVD incidence and suggest the existence of gender-specific genetic risk factors. We aimed to estimate whether the genetic risk profiles of coronary heart disease (CHD), ischemic stroke and the composite end-point of CVD differ between the genders.

Methodology/Principal Findings

We studied in two Finnish population cohorts, using the case-cohort design the association between common variation in 46 candidate genes and CHD, ischemic stroke, CVD, and CVD-related quantitative risk factors. We analyzed men and women jointly and also conducted genotype-gender interaction analysis. Several allelic variants conferred disease risk for men and women jointly, including rs1801020 in coagulation factor XII (HR = 1.31 (1.08–1.60) for CVD, uncorrected p = 0.006 multiplicative model). Variant rs11673407 in the fucosyltransferase 3 gene was strongly associated with waist/hip ratio (uncorrected p = 0.00005) in joint analysis. In interaction analysis we found statistical evidence of variant-gender interaction conferring risk of CHD and CVD: rs3742264 in the carboxypeptidase B2 gene, p(interaction) = 0.009 for CHD, and rs2774279 in the upstream stimulatory factor 1 gene, p(interaction) = 0.007 for CHD and CVD, showed strong association in women but not in men, while rs2069840 in interleukin 6 gene, p(interaction) = 0.004 for CVD, showed strong association in men but not in women (uncorrected p-values). Also, two variants in the selenoprotein S gene conferred risk for ischemic stroke in women, p(interaction) = 0.003 and 0.007. Importantly, we identified a larger number of gender-specific effects for women than for men.

Conclusions/Significance

A false discovery rate analysis suggests that we may expect half of the reported findings for combined gender analysis to be true positives, while at least third of the reported genotype-gender interaction results are true positives. The asymmetry in positive findings between the genders could imply that genetic risk loci for CVD are more readily detectable in women, while for men they are more confounded by environmental/lifestyle risk factors. The possible differences in genetic risk profiles between the genders should be addressed in more detail in genetic studies of CVD, and more focus on female CVD risk is also warranted in genome-wide association studies.

Genetic determinants of carotid ultrasound traits

Atherosclerosis is a complex disease with various intermediate phenotypes that are themselves complex and influenced by many factors. Through the use of carotid ultrasound techniques, the intermediate stages of vascular disease can be imaged and studied for association with potential genetic determinants. In this article we review the most recent available data (reports published since 2004) on the genetic determinants of atherosclerosis, as measured by one-, two-, and three-dimensional ultrasonography of the carotid arteries. In general, associations are disparate and modest. For intima-media thickness, promising associations have been found for both TNFRSF1A R92Q and PPARG P12A, but associations also differed in the same individuals depending on the specific ultrasound trait studied (eg, linear intima-media thickness versus total plaque volume in carotid arteries). Some of the challenging issues for future studies include accounting for gene-environment interactions, sex-specific associations, and the distinctiveness of different carotid ultrasound measures.

Genetic variants predisposing to cardiovascular disease

PURPOSE OF REVIEW

The goal of this review is to provide an update on the most recent and relevant findings in the area of genotype-phenotype associations as well as the relationships between genetic factors and cardiovascular disease risk markers and events. In addition, emphasis will be placed on the methodological problems associated with studying the genetics of complex disorders, specifically cardiovascular diseases.

RECENT FINDINGS

Genes associated with cardiovascular disease predisposition have been examined, including traditional cardiovascular disease candidate genes, such as ACE, AGT, eNOS, PON and MTHFR, new loci that have recently been added to the growing list of cardiovascular disease candidate genes (i.e. MEF2A, ALOX5, LTA, APOM, PDE4D), and genes that have been shown to be at the intersection of several age-related disorders through interaction with one another or with environmental factors (i.e. APOA5, APOE, PPARgamma, LPL and LIPC).

SUMMARY

During the last year, tremendous effort has been made in elucidating new genes associated with cardiovascular disease predisposition. For the most part, however, major breakthroughs have not been made, primarily due to the poor replication of results among studies, as a consequence of poor experimental design. Nevertheless, we have increased our understanding of the complexity of cardiovascular disease and the relevance of gene-environment interactions as the ultimate drivers of the individual predisposition to the disease. It is essential, therefore, that present and future genetic studies in this area take into consideration the inclusion of high-quality environmental data in the analytical process to test the clinical usefulness of a genetic marker as a risk predictor.

Systemic lupus erythematosus in a multiethnic US cohort (LUMINA): XXIII. Baseline predictors of vascular events

OBJECTIVE

To determine the baseline (time 0) risk factors associated with the subsequent occurrence of vascular events in a multiethnic US cohort (LUMINA [LUpus in MInorities: NAture versus nurture]) of patients with systemic lupus erythematosus (SLE).

METHODS

Five hundred forty-six LUMINA patients were assessed at time 0 for traditional and nontraditional (disease-related) risk factors for vascular events. These were defined as 1) cardiovascular (myocardial infarction and/or definite or classic angina and/or the undergoing of a vascular procedure for myocardial infarction [coronary artery bypass graft]), 2) cerebrovascular (stroke), and 3) peripheral vascular (arterial claudication and/or gangrene or significant tissue loss and/or arterial thrombosis in peripheral arteries). The observation time (followup time in the cohort) was the interval between time 0 and the last visit. The unit of analysis was the patient and not each vascular event. Variables at time 0 and vascular events were examined by univariable and multivariable (logistic and Cox proportional hazards regression) analyses. Age, sex, ethnicity, followup time, and all known risk factors for the occurrence of vascular events were included in the model.

RESULTS

Thirty-four patients (6.2%) developed one or more vascular event after time 0. The overall median duration of followup in the cohort was 73.8 months (range 10.8-111.3 months). Vascular events (13 cardiovascular, 18 cerebrovascular, 5 peripheral vascular) occurred in 7 Hispanics from Texas (6.5%), 1 Hispanic from Puerto Rico (1.2%), 15 African Americans (7.5%), and 11 Caucasians (7.1%). The mean total number of traditional risk factors was significantly higher in patients who developed vascular events than in those who did not (7.1 versus 5.6). Independent predictors of vascular events were older age, current smoking status, longer followup time, elevated serum levels of C-reactive protein (CRP), and the presence of any antiphospholipid antibody. The same variables were identified when time-dependent analyses were performed, although azathioprine use was also found to be a contributing factor.

CONCLUSION

Smoking, previously not reported in SLE, emerged as a predictor of vascular events and should be strongly discouraged. Antiphospholipid antibodies and CRP support the role of inflammation and autoimmunity in the development of accelerated atherosclerosis in SLE. Ethnicity was not associated with vascular events in our patients.

Genetics of Ultrasonographic Carotid Atherosclerosis

The search for genes related to the cause of common complex disorders such as cardiovascular disease has been frustrating, partly because of the many factors known to contribute to cardiovascular disease and the potential "distance" of cardiovascular disease as a phenotype from genes and gene products. Linkage and association studies for phenotypes more proximal in the pathway from DNA sequence variation to overt clinical disease, such as ultrasound-defined carotid atherosclerosis, may potentially be more enlightening. Only one genetic variant previously reported to be associated with atherosclerosis or clinically evident cardiovascular disease, matrix metalloproteinase (MMP) 3, has shown consistently positive associations with carotid disease, although it has not been studied widely. Another, PON1 L55M, is weakly associated in subgroups only, and 2, ApoE and MTHFR, are equivocal. Genetic variants reported to be associated with clinical cardiovascular disease show weak or no relationship to carotid atherosclerosis. This may reflect the known inconsistency in associations of genetic variants with clinical cardiovascular disease itself. Alternatively, genetic determinants of ultrasound-defined carotid atherosclerosis may differ from those of clinically manifest cardiovascular disease and may require pursuit through large-scale genomic studies of carotid atherosclerosis as a distinct phenotype. Only 1 genetic variant, MMP 3, has shown consistently positive associations with ultrasonographic carotid disease, although it has not been studied widely. Another, PON1 L55 mol/L, is weakly associated in subgroups only. Genetic variants reported to be associated with clinical cardiovascular disease show weak or no relationship to carotid atherosclerosis.