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. Author manuscript; available in PMC: 2018 Mar 1.
Published in final edited form as: Arthritis Rheumatol. 2017 Mar;69(3):529–541. doi: 10.1002/art.39862

Coronary Artery Calcification and Rheumatoid Arthritis: Lack of Relationship to Risk Alleles for Coronary Artery Disease in the General Population

Iván Ferraz-Amaro 1, Robert Winchester 2, Peter K Gregersen 3, Richard J Reynolds 4, Mary Chester Wasko 5, Anette Oeser 6, Cecilia P Chung 6, C Michael Stein 6, Jon T Giles 2, Joan M Bathon 2
PMCID: PMC5553209  NIHMSID: NIHMS880290  PMID: 27696788

Abstract

Objective

Coronary artery disease (CAD) in the general population is characterized by an increased frequency of particular susceptibility single nucleotide polymorphisms (SNPs). Since CAD is increased in rheumatoid arthritis (RA), we sought to determine whether the frequency of these SNPs are increased in RA patients with CAD, hypothesizing that RA could enhance CAD risk by acting through established genetic pathways predisposing to CAD.

Methods

CAD was assessed by coronary artery calcification (CAC) using computed-tomography in 561 patients with RA. 100 SNPs associated with CAD in the general population were genotyped or imputed and their relation to CAC established through multiple regression analysis for individual SNPs and a genetic risk score (GRS) representing their cumulative effect.

Results

91 CAD SNPs were genotyped successfully; 81 exhibited no association with CAC (Agatston units) or different CAC categorizations, either individually or collectively in the GRS. Only rs579459 (ABO) and rs17676451 (HAL) had a consistent positive association between genotype and CAC score, with a significant increase of the effect allele frequency in both homozygous or heterozygous genotype distributions. 5 were variably negatively associated. Furthermore, a positive association was found between DAS28 and CAC and after adjusting for traditional cardiovascular risk factors it was not modified by correcting for the CAD related SNPs GRS.

Conclusion

The increased risk for CAC in RA does not appear to operate primarily through established genetically regulated atherogenic mechanisms that are preponderant in the general population.

Introduction

Individuals with rheumatoid arthritis (RA) have an increased incidence of cardiovascular events, including myocardial infarctions and cardiac deaths (1). This excess in cardiovascular disease cannot be completely explained by traditional atherosclerosis risk factors, and it is thought to be due to an accelerated atherogenic process that appears to be related to one or more elements in the immune response underlying RA (2).

In the general population, 30-60% of the risk of developing coronary artery disease (CAD) is estimated to be genetic (3). Genome-wide association studies (GWAS) have identified and validated over 100 SNPs that are associated with CAD susceptibility. Moreover, the risk of CAD is proportional to the number of these SNPs inherited by an individual (4-21). These SNPs have been associated with increased risk of CAD through diverse mechanisms, including effects on lipid metabolism, plaque stability, and acute myocardial infarction. Still others act through unknown pathways, suggesting varying impacts of different alleles on the biology and pathophysiology of cardiovascular disease. In particular, some SNPs focus attention on novel and intriguing mechanisms contributing to CAD, such as those mapping to the 53 kb region of chromosome 9p21.3, an area without classic genes that encodes an antisense noncoding RNA in the INK4 locus, designated ANRIL, or CDKN2B-AS1 (22). Homozygosity for 9p21.3 risk alleles confers a population-attributable risk of 21% for CAD (23). Similarly, pathways involving glycotransferase activity encoded at the ABO locus are considered to foster development of myocardial infarction in the general population, acting on the stage after development of atherosclerosis (24).

Coronary artery calcification (CAC) detected by computed tomography is a noninvasive validated measure of subclinical CAD in the general population (25). Direct relationships have been established between CAC scores and histologic, intracoronary ultrasonic, and angiographic measures of coronary artery atherosclerosis and plaque burden on a vessel-by-vessel and segment-by-segment basis (26). CAC has been shown to predict incident myocardial infarction even after adjustment for other traditional cardiovascular risk factors (27). Importantly, analogous to CAD, the presence of CAC is also a heritable trait (28) and CAC is significantly higher in individuals with a parental history of CAD (29). In the general population, it is now recognized that many of SNPs predominantly exert their influence at different stages of the biologic events leading to the ultimate development of myocardial infarction, including atherosclerosis, CAC, and CAD (24), and the presence of CAC analogously has been linked to the SNPs associated with CAD across multiple genetic loci (5, 30).

In RA, both the prevalence of positive CAC scores and their magnitude are significantly increased compared with the general population (31). Elevated CAC scores in RA patients have also been shown to independently predict cardiovascular events (32).

Accordingly, we sought to determine whether in the subset of RA patients with CAC, the frequency of the SNPs associated with CAD in the general population would also be significantly increased over their frequency in the subset of RA patients without CAC. If this were found to be the case, it would imply that the effect of RA is to enhance the risk for CAD by acting through established genetic pathways that result in CAD in the general population, resulting in an increase of RA patients having these susceptibility genes in the group with CAC. Alternatively, if the frequencies of these alleles were not found to be significantly increased among RA patients with CAC, it would suggest that increased CAC in RA is a consequence of RA-associated immune mediated mechanisms that act independently of the genetically determined proatherosclerotic pathways operating in the general population.

Material and methods

Study participants and data collection

A total of 561 patients with RA from three different clinic-based cohorts (the ESCAPE-RA cohort from Johns Hopkins University, and two additional cohorts from the University of Pittsburgh and Vanderbilt University) were included in this study. All patients were men or women who were diagnosed by a rheumatologist and who fulfilled the American Rheumatism Association 1987 revised criteria for the classification of RA (33). The ESCAPE-RA (Evaluation of Subclinical Cardiovascular disease And Predictors of Events in Rheumatoid Arthritis) study has been described in detail previously (31) and was initiated to study the prevalence, progression, and risk factors for subclinical cardiovascular disease in RA. A total of 197 patients aged 45 to 80 years old with a disease duration >6 months, were recruited from the Johns Hopkins Arthritis Center. The Pittsburgh cohort consisted of 195 patients recruited from the University of Pittsburgh Medical Center Arthritis Network outpatient practices. For this cohort patients were only women, 16 years old or older, and disease duration was ≥ 2 years. In the Vanderbilt cohort, patients were a minimum age of 18 years old and there were two groups of patients: duration of disease of <5 years (early RA) or >10 years (established RA). In this cohort 169 patients were obtained from a registry of patients with early RA, were referred by local rheumatologists, or were recruited by advertisements. Details of the Pittsburgh and Vanderbilt cohorts have also been previously reported (34, 35). Each study was approved by the Institutional Review Board of the universities and hospitals of the three cohorts with all subjects providing written informed consent prior to enrollment.

Assessments and CAC quantification

Age, gender, race/ethnicity, current and past smoking were assessed from patient-self report. Ninety percent of patients in the three cohorts were of Caucasian ethnicity. Patients filled in a medication usage questionnaire and underwent examination to assess anthropometric measures and blood pressure. Medical records were reviewed to ascertain diagnosis and medication. Current and past use of glucocorticoids, biologic and non-biologic disease modifying antirheumatic drugs use was queried by detailed examiner-administered questionnaires. Disease activity was measured using the Disease Activity Score in 28 joints (DAS28) through erythrocyte sedimentation rate (ESR) or C-reactive protein (CRP), while the degree of disease disability was determined using the Health Assessment Questionnaire (HAQ). Metabolic syndrome was defined using the 2005 National Cholesterol Education Program Adult Treatment Panel III (ATP III) criteria.

Fasting plasma and serum samples were collected and frozen until analysis of circulating lipids, glucose, insulin, high sensitivity C-reactive protein and homocysteine. Rheumatoid factor was assessed by nephelometry with seropositivity defined at or above a level of 40 units. All subjects underwent cardiac computerized tomography using methodology described previously (36). CAC was quantitated using the Agatston method (37). In addition to the Agatston score as a continuous variable, CAC was also categorized as greater than 0 and greater than 10 Agatston units, and 75th and 90th CAC percentiles, adjusted for age, gender and race/ethnicity, were also defined as previously described (38).

Genotyping, imputation, and genetic risk score calculation

We identified SNPs of interest from genome-wide association studies published up to 2014 in which phenotypes studied were myocardial infarction, angiographically defined CAD, and CAC, which we refer to collectively as “CAD”, and where the association between a SNP and CAD exceeded a genome-wide association threshold (p<5×108). We identified 100 CAD related disease SNPs in the literature (4-21). Supplementary Table 1 shows the selected SNPs with details of their gene information, effect and non-effect alleles and published odd ratio (OR), or beta coefficient, association effect. RA patients were genotyped using the Immunochip. This is an Illumina Infinium genotyping chip, containing 196,524 polymorphisms (718 small insertion deletions, 195,806 SNPs) designed both to perform deep replication of major autoimmune and inflammatory diseases, and fine-mapping of established GWAS significant loci (39). Because some CAD SNPs in the GWAS studies were identified using alternative chips, such as the Metabochip (40) with a different selection of SNPs not present on the Immunochip, it was necessary to impute these un-typed SNPs using Impute2 software (41) after being ‘pre-phased’ using SHAPEIT (42). SNPs with low imputation quality, minor allele frequency <1% or Hardy–Weinberg equilibrium <0.001 were excluded. Of the 100 selected SNPs, 9 were neither able to be genotyped nor successfully imputed (rs17114036, rs6783981, rs1878406, rs273909, rs12205331, rs9268402, rs3184504, rs2895811, rs17228213). A multilocus genetic risk score (GRS) was constructed as previously described using Plink 1.07 software (43) for each individual by summing the number of CAD alleles (0/1/2) for each of the 86 SNPs weighted by their estimated effect sizes (OR) (rs6783981, rs2026458, rs10811647, rs17676451, rs3809346, rs8001186 were not include in the genetic risk calculation because OR information was not available). Missing genotype values in the GRS calculation were imputed with the cohort-specific averages of risk allele frequencies. Supplementary Table 1 shows SNP specific weights.

Statistical analysis

The hypothesis to be tested in this study design was that in the subset of RA patients with CAC, the frequency of the SNPs known, a priori from the literature, to be associated with CAD in the general population would be significantly increased in frequency in the subset of RA patients with CAC, versus their frequency in those RA patients without CAC. Accordingly the correction for multiple comparisons required in a study with a posteriori hypotheses is not appropriate in this study design. In terms of study power, on the basis of previously published findings (44) we assumed that smoking, hypertension and diabetes are associated with approximately 50% of the risk of an acute myocardial infarction. In a European cohort (45), a GRS created from three SNPs that have been credibly associated with CAC explained 2.4 % of the variation in CAC, and a 45-SNP GRS constructed from CAD-associated SNPs explained an additional 4 %. Proceeding with these conservative assumptions, in a multivariable regression model with a α level of 0.05 and a β level of 0.10, and assuming a coefficient of determination of 50% and that this would increase to 52% when adding GRS to the model, we estimated that we would need to enroll 425 subjects.

The distributions of all variables were examined. Means and standard deviations were calculated for all normally distributed continuous variables and medians and interquartile ranges were calculated for continuous variables that were not normally distributed. For categorical variables, counts and percentages were calculated. CAC scores were modeled as the natural log of the CAC score plus 1, in order to account for zero scores. In table 2 CAC Agatston units are expressed as median (interquartile range) and U Mann-Whitney test were used to test for the differences in CAC units between allele groups. In this sense, Table 2 describes the comparison of effect allele homozygous vs. heterozygous, and the comparison of the effect allele vs. the non-effect. Similarly, logistic regression analysis adjusted for traditional cardiovascular risk factors (age, sex, diabetes, hypertension, dyslipidemia, and smoking) was used to also study the relation of homozygous against heterozygous, or for the relation of affected allele against the non affected, with CAC expressed as higher than 0 and 10 units or higher than 70th and 90th percentiles. This association analysis in Table 2 was performed using SNPTEST that can account for some imputation uncertainty (46). Linear trends for the association of GRS and CAC were tested using linear regression with orthogonal polynomial contrasts. To assess the relationship of CAC and GRS with DAS28, three models were constructed, one adjusted for age and sex (model 1), model 2 adjusted for model 1 plus traditional cardiovascular risk factors (diabetes, hypertension, smoking and dyslipemia) and model 3 that was constructed by adding GRS to both model 1 and 2. All statistical calculations were performed using SPSS software, version 21 (IBM). In all tests, a two-tailed alpha of 0.05 was defined as the level of statistical significance.

Table 2. Multivariable regression and association analysis of cardiovascular disease related SNPs relation with coronary artery calcification.

rs Chr Gene/ nearest
gene
Effect/
non
effect
allele
Risk
allele
frequency
Published OR
(95%CI)
Ref Effect
allele
n CAC (units) OR (95%CI)

p CAC > 0 CAC > 10 CAC > p75 CAC > p90
rs6604023 1 CDC7 C/G 0.09 1.19 (1.13-1.26)

cell division cycle 7 7,8 CC 3 6 (0-114) 0.91 0.45 (0.21-0.99) 0.58 (0.26-1.28) 0.66 (0.31-1.43) 0.79 (0.34-1.84)
intragenic CG 24 0 (0-14)
GG 131 4 (0-123)

C 27 0 (0-14) 0.05 1.08 (0.42-2.79) 1.11 (0.43-2.88) 1.13 (0.44-2.89) 1.21 (0.46-3.13)
G 131 4 (0-123)

rs4845625 1 IL6R T/C 0.43 1.04 (1.02-1.07) 6

interleukin 6 receptor TT 74 3 (0-104) 0.96 1.09 (0.66-1.82) 1.11 (0.66-1.86) 1.25 (0.76-2.05) 0.99 (0.57-1.73)
intron TC 215 1 (0-152)
CC 134 2 (0-107)

T 289 1 (0-129) 0.77 1.48 (0.83-2.61) 1.44 (0.81-2.58) 1.45 (0.83-2.52) 1.59 (0.87-2.91)
C 134 2 (0-107)
rs17465637 1 MIA3 C/A 0.69 1.20 (1.12-1.30) 8,9,10

melanoma inhibitory activity family, member 3 CC 196 1 (0-116) 0.68 1.14 (0.70-1.84) 1.33 (0.81-2.17) 1.01 (0.64-1.62) 1.24 (0.73-2.10)
intron AC 193 3 (0-135)
AA 36 0 (0-46)

C 389 2 (0-128) 0.27 1.16 (0.56-2.37) 1.41 (0.67-2.95) 1.23 (0.60-2.52) 1.34 (0.61-2.93)
A 36 0 (0-46)
rs11206510 1 PCSK9 T/C 0.86 1.15 (1.10-1.21) 6,8,10

proprotein convertase subtilisin/kexin type 9 TT 76 1 (0-123) 0.97 - - - -
intragenic CT 26 1 (0-40)
CC 1 202

T 102 1 (0-102) 0.37 - - - -
C 1 202
rs602633 1 PSRC1 G/T 0.72 1.13 6

proline/serine-rich coiled-coil 1 GG 113 8 (0-116) 0.03 1.14 (0.52-2.50) 1.17 (0.53-2.61) 0.97 (0.44-2.11) 1.04 (0.45-2.39)
intragenic TG 77 0 (0-26)
TT 21 1 (0-335)

G 190 1 (0-114) 0.85 1.69 (0.9-3.2) 1.75 (0.9-3.38) 1.60 (0.85-3.02) 1.46 (0.72-2.93)
T 21 1 (0-335)
rs599839 1 PSRC1 A/G 0.69 1.29 (1.18-1.40) 6,9,10

proline/serine-rich coiled-coil 1 AA 96 11 (0-128) 0.06 1.16 (0.53-2.53) 1.23 (0.55-2.77) 1.02 (0.47-2.22) 1.08 (0.47-2.48)
5′ exon 1 GA 78 0 (0-117)
GG 21 1 (1-335)

A 174 1 (0-128) 0.96 1.64 (0.86-3.13) 1.85 (0.94-3.63) 1.58 (0.84-3,00) 1.30 (0.65-2.61)
G 21 1 (1-335)
rs17464857 1 TAF1A T/C 0.84 1.02 6

TATA box binding protein (TBP)-associated factor, RNA polymerase I, A, 48kDa TT 297 3 (0-135) 0.12 1.01 (0.41-2.48) 1.10 (0.44-2.72) 1.07 (0.44-2.63) 1.22 (0.49-3.04)
intron 1 TG 118 0 (0-86)
GG 9 5 (0-111)

T 415 2 (0-120) 0.95 1.13 (0.67-1.89) 1.24 (0.73-2.12) 1.23 (0.74-2.05) 1.28 (0.71-2.29)
G 9 5 (0-111)
rs646776 1 CELSR2 T/C 0.84 1.14 (1-09-1.19) 11

cadherin, EGF LAG seven-pass G-type receptor 2 TT 129 8 (0-122) 0.02 1.25 (0.64-2.42) 1.72 (0.85-3.48) 1.65 (0.82-3.29) 1.30 (0.63-2.71)
intragenic 3′ CT 53 0 (0-22)
CC 4 0 (0-1)

T 182 1 (0-116) 0.15 1.07 (0.43-2.63) 1.16 (0.46-2.94) 0.97 (0.39-2.42) 1.14 (0.45-2.89)
C 4 0 (0-1)
rs6544713 2 ABCG8 T/C 0.31 1.06 (1.04-1.09) 6

ATP-binding cassette, sub-family G (WHITE), member 8 TT 37 0 (0-54) 0.45 1.32 (0.81-2.14) 1.46 (0.89-2.40) 1.35 (0.84-2.16) 1.14 (0.67-1.95)
intron TC 185 3 (0-119)
CC 202 2 (0-128)

T 222 1 (10-116) 0.70 0.98 (0.49-1.97) 1.05 (0.51-2.15) 0.88 (0.44-1.75) 1.08 (0.52-2.23)
C 202 2 (0-128)
rs6725887 2 WDR12 C/T 0.12 1.17 (1.11-1.23) 6,8

WD repeat domain 12 CC 6 141 (40-269) 0.15 1.17 (0.46-3.01) 1.23 (0.48-3.17) 1.03 (0.41-2.60) 1.14 (0.45-2.92)
intron CT 86 0 (0-77)
TT 333 2 (0-123)
C 92 0 (0-105) 0.43 1.12 (0.64-1.96) 1.20 (0.68-2.14) 1.16 (0.67-2.00) 1.17 (0.64-2.14)
T 333 2 (0-123)

rs515135 2 APOB C/T 0.78 1.08 (1.05-1.11) 6

apolipoprotein B CC 271 3 (0-155) 0.22 0.96 (0.58-1.58) 1.17 (0.70-1.95) 1.07 (0.66-1.74) 1.63 (0.92-2.89)
intragenic CT 122 0 (0-77)
TT 32 2 (0-97)

C 393 1 (0-123) 0.95 0.94 (0.44-1.98) 1.09 (0.52-2.31) 0.87 (0.42-1.81) 1.04 (0.47-2.28)
T 32 2 (0-97)
rs2252641 2 TEX41 C/T 0.13 1.06 6

testis expressed 41 CC 3 3 (0-55) 0.95 - - - -
intron TC 19 1 (0-9)
TT 73 4 (0-93)

C 22 1 (0-15) 0.25 - - - -
T 73 4 (0-93)
rs1561198 2 VAMP5 A/G 0.54 1.05 (1.03-1.07) 6

vesicle-associated membrane protein AA 30 0 (0-77) 0.31 - - - -
intragenic AG 37 8 (0-138)
GG 22 28 (0-91)

A 67 3 (0-123) 0.47 - - - -
G 22 28 (0-91)
rs2943634 2 IRS1 C/A 0.65 1.08 (0.90-1.31) 8,9

insulin receptor substrate 1 CC 180 4 (0-105) 0.75 1.09 (0.67-1.79) 1.13 (0.68-1.88) 0.97 (0.60-1.56) 1.36 (0.79-2.33)
intragenic AC 192 1 (0-117)
AA 50 0 (0-269)

C 372 2 (0-114) 0.66 1.13 (0.59-2.16) 0.93 (0.48-1.80) 0.88 (0.47-1.65) 0.74 (0.38-1.47)
A 50 0 (0-269)
rs2123536 2 WDR35 T/C 0.03 1.12 (1.08-1.16) 12

WD repeat domain 35 TT 1 0 0.48 - - - -
intragenic TC 8 37 (0-81)
CC 144 3 (0-129)

T 9 5 (0-68) 0.86 - - - -
C 144 3 (0-129)
rs9818870 3 MRAS T/C 0.15 1.07 6

muscle RAS oncogene homolog TT 13 1 (0-510) 0.73 1.07 (0.62-1.84) 1.20 (0.69-2.08) 1.17 (0.70-1.98) 1.19 (0.67-2.13)
3′UTR TC 101 2 (0-123)
CC 311 1 (0-116)

T 114 2 (0-123) 0.85 0.95 (0.40-2.24) 0.89 (0.37-2.10) 1.09 (0.47-2.51) 1.41 (0.60-3.34)
C 311 1 (0-116)
rs2306374 3 MRAS C/T 0.15 1.15 (1.11–1.19) 6,1

muscle RAS oncogene homolog CC 12 0 (0-455) 0.85 0.93 (0.39-2.21) 0.86 (0.36-2.07) 0.97 (0.41-2.27) 1.19 (0.49-2.87)
intron TC 103 3 (0-126)
TT 310 2 (0-116)

C 115 2 (0-129) 0.85 1.03 (0.60-1.76) 1.24 (0.72-2.16) 1.22 (0.73-2.05) 1.17 (0.66-2.09)
T 310 2 (0-116)
rs1199338 3 MRAS C/A 0.19 1.08 (1-02-1.13) 11

muscle RAS oncogene homolog CC 7 0 (0-28) 0.51 - - - -
intron CA 38 2 (0-95)
AA 89 2 (0-109)

C 45 0 (0-68) 0.64 - - - -
A 89 2 (0-109)
rs7692387 4 GUCY1A3 G/A 0.89 1.06 (1.03-1.09) 6

guanylatecyclase 1, soluble, alpha 3 GG 263 2 (0-128) 0.51 1.31 (0.71-2.44) 0.98 (0.52-1.87) 0.94 (0.51-1.74) 0.95 (0.48-1.87)
intron AG 63 0 (0-111)
AA 5 8 (6-269)

G 326 1 (0-123) 0.35 0.68 (0.28-1.67) 0.75(0.30-1.87) 0.81 (0.33-2.00) 0.75 (0.30-1.86)
A 5 8 (6-269)
rs1842896 4 GUCY1A3 T/G 0.94 1.14 (1.10-1.19) 12

guanylatecyclase 1, soluble, alpha 3 TT 21 0 (0-205) 0.51 - - - -
intragenic GT 3 5 (2-59)
GG 0 -

T 24 0 (0-90) - - - - -
G 0 -
rs11748327 5 IRX1 C/T 0.79 1.25 13

iroquoishomeobox 1 CC 198 1 (0-144) 0.58 - - - -
intragenic TC 100 1 (0-68)
TT 17 1 (0-110)

C 298 0 (0-90) 0.98 - - - -
T 12 1 (0-110)
rs17609940 6 ANKS1A G/C 0.82 1.07 (1.05-1.10) 6,1

ankyrin repeat and sterile alpha motif domain containing 1A GG 285 1 (0-121) 0.50 0.96 (0.58-1.57) 0.76 (0.46-1.27) 0.83 (0.51-1.34) 0.68 (0.39-1.17)
intron CG 123 6 (0-123)
CC 17 0 (0-63)

G 408 2 (0-122) 0.50 1.09 (0.47-2.53) 0.94 (0.40-2.20) 1.15 (0.50-2.65) 0.88 (0.37-2.09)
C 17 0 (0-63)
rs3869109 6 HCG27 G/A 0.59 1.14 14

Human leucocyte antigen C GG 145 7 (0-138) 0.12 1.45 (0.88-2.38) 1.59 (0.95-2.64) 1.50 (0.93-2.42) 1.35 (0.79-2.32)
intragenic AG 213 0 (0-116)
AA 66 0 (0-111)

G 358 2 (0-123) 0.49 1.40 (0.74-2.66) 1.62 (0.84-3.15) 1.27 (0.67-2.38) 1.81 (0.88-3.76)
A 66 0 (0-111)
rs10947789 6 KCNK5 T/C 0.95 1.06 (1.03-1.08) 6

potassium channel, subfamily K, member 5 TT 96 5 (0-81) 0.91 - - - -
intron CT 11 0 (0-320)
CC 0 -

T 107 5 (0-119) - - - - -
C 0 -
rs3798220 6 LPA C/T 0.02 1.92 (1.48-2.49) 6,10,15

lipoprotein A CC 0 - - - - - -
exon TC 18 1 (0-105)
TT 407 2 (0-121)

C 18 1 (0-105) 0.92 1.26 (0.58-2.70) 0.88 (0.40-1.92) 0.92 (0.43-1.96) 0.94 (0.42-2.14)
T 407 2 (0-121)
rs10455872 6 LPA G/A 0.05 1.70 (1.49-1.95) 15

lipoprotein A GG 0 - - - - - -
intron GA 45 7 (0-226)
AA 378 1 (0-114)

G 45 7 (0-226) 0.18 1.06 (0.56-2.04) 0.83 (0.44-1.60) 0.84 (0.44-1.59) 1.02 (0.51-2.06)
A 378 1 (0-114)
rs2048327 6 SLC22A3 G/A 0.25 1.06 6

solute carrier family 22 (organic cationtransorter), member 3 GG 13 2 (0-279) 0.47 1.13 (0.64-2.01) 1.13 (0.63-2.03) 0.94 (0.54-1.65) 0.84 (0.44-1.60)
intron GA 117 3 (0-150)
AA 154 0 (0-107)

G 130 0.49 1.27 (0.55-2.93) 0.89 (0.38-2.09) 0.95 (0.41-2.22) 1.12 (0.47-2.67)
A 154 0 (0-107)
rs6922269 6 MTHFD1L A/G 0.28 1.23 (1.01-1.50) 8,9

methylenetetrahydrofolate dehydrogenase (NADP+ dependent) 1-like AA 37 0 (0-123) 0.68 1.17 (0.72-1.90) 1.08 (0.66-1.77) 0.87 (0.54-1.39) 0.89 (0.52-1.52)
intron AG 167 3 (0-114)
GG 221 1 (0-128)

A 204 2 (0-116) 0.78 0.92 (0.45-1.88) 0.86 (0.42-1.77) 0.64 (0.31-1.31) 0.88 (0.41-1.88)
G 221 1 (0-128)
rs9369640 6 PHACTR1 A/C 0.27 1.09 6

phosphatase and actin regulator 1 AA 20 18 (0-281) 0.13 0.61 (0.35-1.06) 0.82 (0.47-1.43) 0.74 (0.43-1.28) 0.76 (0.41-1.41)
intron AC 117 0 (0-32)
CC 159 5 (0-150)

A 137 0 (0-38) 0.01 1.00 (0.42-2.35) 0.81 (0.34-1.93) 0.68 (0.28-1.62) 0.78 (0.32-1.90)
C 159 5 (0-150)
rs12526453 6 PHACTR1 C/G 0.30 1.13 (1.09–1.17) 6,8,10

phosphatase and actin regulator 1 CC 39 3 (0-218) 0.64 0.71 (0.44-1.15) 0.96 (0.58-1.57) 0.87 (0.54-1.39) 0.79 (0.46-1.35)
intron CG 176 0 (0-64)
GG 210 4 (0-179)

C 215 0 (0-70) 0.03 0.93 (0.43-1.98) 0.78 (0.36-1.70) 0.73 (0.34-1.55) 0.72 (0.32-1.64)
G 210 4 (0-179)
rs9349379 6 PHACTR1 A/G 0.91 1.26 (1.14-1.14) 7,16

phosphatase and actin regulator 1 AA 206 5 (0-191) 0.10 - - - -
intron GA 41 0 (0-48)
GG 2 109 (0-218)

A 247 4 (0-147) 0.99 1.27 (0.64-2.51) 0.94 (0.47-1.89) 1.03 (0.52-2.03) 1.01 (0.49-2.11)
G 2 109 (0-218)
rs1332844 6 PHACTR1 C/T 0.74 1.11 (1.07-1.15) 11

phosphatase and actin regulator 1 CC 155 5 (0-150) 0.01 1.01 (0.43-2.38) 1.24 (0.52-2.94) 1.51 (0.64-3.59) 1.32 (0.54-3.23)
intron TC 115 0 (0-31)
TT 18 24 (0-343)

C 270 1 (0-95) 0.08 1.70 (0.99-2.93) 1.29 (0.74-2.25) 1.47 (0.85-2.54) 1.28 (0.69-2.35)
T 18 24 (0-343)
rs2026458 6 PHACTR1 T/C 0.07 0.16 (0.03)* 7

phosphatase and actin regulator 1 TT 1 218 0.44 - - - -
intron TC 17 29 (0-119)
CC 113 3 (0-150)

T 18 30 (0-121) 0.80 - - - -
C 113 3 (0-150)
rs4252120 6 PLG T/C 0.95 1.06 (1.03-1.09) 6

plasminogen TT 48 4 (0-173) 0.76 - - - -
intron TC 5 3 (0-13)
CC 0 -

T 53 4 (0-166) - - - - -
C 0 -
rs12190287 6 TCF21 C/G 0.35 1.08 (1.06-1.10) 6, 10

transcription factor 21 CC 52 2 (0-116) 0.83 0.75 (0.46-1.22) 0.71 (0.43-1.18) 0.77 (0.47-1.24) 0.93 (0.54-1.61)
exon CG 192 1 (0-129)
GG 181 2 (0-118)

C 244 1 (0-123) 0.99 0.99 (0.52-1.91) 0.76 (0.39-1.48) 1.11 (0.59-2.11) 0.96 (0.48-1.94)
G 52 2 (0-118)
rs6905288 6 VEGFA T/C 0.58 1.23 14

vascular endothelial growth factor A TT 146 3 (0-158) 0.33 0.83 (0.48-1.44) 0.76 (0.44-1.34) 0.89 (0.52-1.52) 0.89 (0.49-1.62)
intragenic TC 199 1 (0-125)
CC 80 2 (0-61)

T 345 1 (0-129) 0.43 1.17 (0.71-1.94) 1.08 (0.64-1.80) 1.26 (0.78-2.05) 1.08 (0.62-1.86)
C 80 2 (0-61)
rs12539895 7 COG5 A/C 0.03 1.02 6

component of oligomericgolgi complex 5 AA 0 - - - - - -
intron AC 6 46 (1-160)
CC 114 2 (0-116)

A 6 46 (1-160) 0.66 - - - -
C 120 2 (0-116)
rs2023938 7 HDAC9 G/A 0.09 1.07 (1.04-1.11) 6

histone deacetylase 9 GG 7 0 (0-202) 0.72 0.88 (0.49-1.59) 1.11 (0.61-2.04) 0.97 (0.54-1.72) 1.15 (0.61-2.16)
exon GA 63 1 (0-128)
AA 343 2 (0-121)

G 70 0 (0-128) 0.84 0.80 (0.34-1.92) 0.92 (0.38-2.22) 0.97 (0.41-2.29) 0.97 (0.40-2.35)
A 343 2 (0-121)
rs11556924 7 ZC3HC1 C/T 0.91 1.09 (1.07-1.12) 6, 10

zinc finger, C3HC-type containing 1 CC 30 0 (0-66) 0.98 - - - -
exon CT 7 0 (0-28)
TT 0 -

C 37 0 (0-47) - - - - -
T 0 -
rs10953541 7 BCAP29 C/T 0.97 1.08 (1.05–1.11) 11

B-cell receptor-associated protein 29 CC 103 2 (0-129) 0.55 - - - -
intron CT 6 1 (0-46)
TT 0 -

C 109 1 (0-121) - - - - -
T 0 -
rs264 8 LPL G/A 0.95 1.05 (1.02-1.08) 6

lipoprotein lipase GG 241 2 (0-116) 0.83 1.11 (0.51-2.39) 0.94 (0.44-2.02) 1.02 (0.48-2.16) 0.84 (0.38-1.87)
intron AG 26 1 (0-179)
AA 0 -

G 267 2 (0-117) - - - - -
A 0 -
rs2954029 8 (TRIB1)LOC105375745 A/T 0.55 1.04 (1.02-1.06) 6

(tribbles homolog 1) LOC105375745 AA 120 5 (0-128) 0.20 0.72 (0.41-1.24) 0.81 (0.47-1.42) 0.76 (0.45-1.29) 0.73 (0.41-1.30)
intron TA 223 0 (0-116)
TT 78 4 (0-137)

A 343 1 (0-121) 0.33 1.10 (0.65-1.86) 0.88 (0.51-1.51) 0.91 (0.54-1.52) 1.02 (0.57-1.82)
T 78 4 (0-137)
rs579459 9 ABO C/T 0.23 1.10 (1.07-1.13) 6, 10

ABO blood group CC 23 122 (4-619) 0.01 1.25 (0.59-2.64) 1.46 (0.70-3.06) 1.34 (0.66-2.71) 1.34 (0.63-2.85)
intragenic CT 146 4 (0-129)
TT 256 0 (0-110)

C 169 6 (0-186) 0.03 1.32 (0.81-2.14) 1.24 (0.75-2.03) 1.00 (0.63-1.60) 1.18 (0.70-2.01)
T 256 0 (0-110)
rs3217992 9 CDKN2B-AS1 A/G 0.25 1.14 6

CDKN2B antisense RNA 1 AA 12 34 (0-290) 0.38 1.05 (0.47-2.37) 1.42 (0.63-3.19) 1.30 (0.59-2.89) 1.31 (0.56-3.07)
antisense RNA AG 84 2 (0-116)
GG 121 0 (0-105)

A 96 3 (0-147) 0.34 1.07 (0.58-1.95) 1.16 (0.62-2.15) 1.10 (0.6-2.01) 1.06 (0.53-2.11)
G 121 0 (0-105)
rs1333049 9 CDKN2B-AS1 C/G 0.55 1.28 (1.07.1.53) 7,9

CDKN2B antisense RNA 1 CC 123 1 (0-116) 0.63 0.95 (0.54-1.68) 0.95 (0.53-1.72) 1.14 (0.64-2.01) 0.77 (0.42-1.43)
antisense RNA CG 215 3 (0-149)
GG 82 0 (0-81)

C 338 2 (0-128) 0.25 0.96 (0.57-1.63) 0.89 (0.52-1.54) 0.82 (0.49-1.39) 0.99 (0.56-1.77)
G 82 0 (0-81)
rs10757274 9 CDKN2B-AS1 G/A 0.46 1.29 (1.06-1.58) 17

CDKN2B antisense RNA 1 GG 94 0 (0-95) 0.38 0.96 (0.56-1.65) 1.07 (0.61-1.87) 1.06 (0.62-1.81) 1.24 (0.69-2.23)
antisense RNA GA 203 3 (0-175)
AA 128 0 (0-111)

G 297 3 (0-128) 0.39 1.33 (0.79-2.24) 1.38 (0.81-2.37) 1.50 (0.89-2.53) 1.18 (0.66-2.11)
A 128 0 (0-111)
rs1333040 9 CDKN2B-AS1 C/T 0.42 1.13 6

CDKN2B antisense RNA 1 CC 76 0 (0-118) 0.65 0.62 (0.34-1.13) 0.79 (0.43-1.46) 0.60 (0.33-1.10) 0.95 (0.49-1.81)
antisense RNA CT 206 3 (0-128)
TT 143 1 (0-114)

C 282 2 (0-124) 0.75 0.71 (0.43-1.18) 0.75 (0.45-1.25) 0.75 (0.46-1.22) 0.76 (0.44-1.32)
T 143 1 (0-114)
rs10811647 9 CDKN2B-AS1 C/G 0.36 -0.212 (0.031)* 7

CDKN2B antisense RNA 1 CC 36 0 (0-95) 0.48 1.17 (0.59-2.33) 0.96 (0.48-1.92) 0.94 (0.48-1.86) 0.97 (0.45-2.11)
antisense RNA CG 115 3 (0-129)
GG 108 0 (0-110)

C 151 2 (0-125) 0.57 1.25 (0.54-1.63) 1.23 (0.51-1.67) 1.01 (0.41-1.35) 1.11 (0.43-1.65)
G 108 0 (0-110)
rs2891168 9 CDKN2B-AS1 G/A 0.46 1.29 (1.20-1.38) 18

CDKN2B antisense RNA 1 GG 90 0 (0-68) 0.27 0.95 (0.55-1.64) 1.03 (0.58-1.81) 1.02 (0.59-1.76) 1.23 (0.68-2.25)
antisense RNA GA 199 0 (0-147)
AA 125 0 (0-113)

G 289 2 (0-121) 0.52 1.32 (0.77-2.24) 1.30 (0.76-2.24) 1.46 (0.86-2.48) 1.10 (0.61-1.98)
A 125 0 (0-113)
rs4977574 9 CDKN2B-AS1 G/A 0.45 1.29 (1.23-1.36) 6,8,10

CDKN2B antisense RNA 1 GG 90 0 (0-68) 0.24 0.94 (0.54-1.63) 1.02 (0.58-1.80) 1.01 (0.59-1.74) 1.23 (0.67-2.23)
antisense RNA GA 201 3 (0-175)
AA 128 0 (0-111)

G 291 2 (0-128) 0.46 1.31 (0.78-2.21) 1.35 (0.79-2.32) 1.46 (0.86-2.46) 1.16 (0.64-2.07)
A 128 0 (0-111)
rs10757278 9 CDKN2B-AS1 G/A 0.46 1.27 (1.19-1.36) 17

CDKN2B antisense RNA 1 GG 87 0 (0-68) 0.22 1.11 (0.63-1.95) 1.12 (0.62-2.02) 0.96 (0.55-1.68) 1.24 (0.67-2.27)
antisense RNA GA 213 3 (0-175)
AA 125 1 (0-113)

G 300 2 (0-128) 0.59 1.05 (0.62-1.77) 1.10 (0.64-1.90) 1.17 (0.69-1.96) 1.02 (0.57-1.83)
A 125 1 (0-113)
rs2383207 9 CDKN2B-AS1 G/A 0.56 1.27 (1.18-1.36) 17

CDKN2B antisense RNA 1 GG 140 0 (0-68) 0.13 0.97 (0.58-1.60) 0.81 (0.48-1.37) 0.85 (0.51-1.39) 0.97 (0.55-1.70)
antisense RNA GA 192 3 (0-177)
AA 89 1 (0-116)

G 332 2 (0-123) 0.72 1.12 (0.63-1.99) 0.99 (0.55-1.80) 1.11 (0.63-1.98) 1.02 (0.54-1.92)
A 89 1 (0-116)
rs2383206 9 CDKN2B-AS1 G/A 0.50 1.30 (1.06-1.58) 17

CDKN2B antisense RNA 1 GG 98 0 (0-68) 0.19 0.99 (0.57-1.70) 0.98 (0.56-1.72) 0.96 (0.56-1.65) 1.14 (0.63-2.06)
antisense RNA GA 192 3 (0-177)
AA 97 1 (0-116)

G 290 2 (0-128) 0.66 0.86 (0.68-2.11) 0.81 (0.60-1.92) 1.00 (0.76-2.37) 0.86 (0.61-2.15)
A 97 1 (0-116)
rs1537373 9 CDKN2B-AS1 G/T 0.54 1.19 (1.07-1.31) 16

CDKN2B antisense RNA 1 GG 131 0 (0-95) 0.27 1.27 (0.72-2.22) 1.06 (0.60-1.88) 1.23 (0.71-2.14) 0.99 (0.54-1.81)
antisense RNA GT 194 3 (0-147)
TT 99 0 (0-116)

G 325 2 (0-123) 0.61 1.33 (0.59-1.63) 1.21 (0.50-1.44) 1.33 (0.57-1.55) 1.26 (0.61-1.86)
T 99 0 (0-116)
rs10965219 9 CDKN2B-AS1 G/A 0.49 1.16 (1.05-1.29) 16

CDKN2B antisense RNA 1 GG 66 4 (0-147) 0.50 1.08 (0.59-1.96) 1.19 (0.65-2.20) 0.98 (0.54-1.77) 0.95 (0.48-1.84)
antisense RNA GA 123 0 (0-65)
AA 70 2 (0-129)

G 189 0 (0-81) 0.41 0.86 (0.46-1.59) 0.75 (0.4-1.41) 0.89 (0.48-1.64) 0.80 (0.41-1.57)
A 70 2 (0-129)
rs7025486 9 DAB2IP A/G 0.15 1.10 (1.06-1.14) 19

DAB2 interacting protein AA 5 0 (0-28) 0.93 - - - -
intronic AG 16 0 (0-11)
GG 65 0 (0-111)

A 21 0 (0-17) 0.40 - - - -
G 65 0 (0-111)
rs12413409 10 CNNM2 G/A 0.92 1.12 (1.08-1.16) 6,10

cyclin M2 GG 360 1 (0-128) 0.91 1.02 (0.56-1.86) 0.95 (0.51-1.76) 0.94 (0.52-1.69) 1.03 (0.54-1.96)
intronic AG 60 3 (0-119)
AA 5 24 (0-30)

G 420 2 (0-121) 0.97 0.88 (0.34-2.26) 0.84 (0.32-2.18) 0.87 (0.34-2.24) 1.07 (0.41-2.77)
A 5 24 (0-30)
rs501120 10 CXCL12 A/G 0.85 1.33 (1.20-1.48) 9

chemokine (C-X-C motif) ligand 12 AA 307 3 (0-128) 0.33 0.87 (0.39-1.90) 1.31 (0.59-2.91) 0.83 (0.38-1.82) 1.19 (0.51-2.79)
intragenic GA 96 0 (0-93)
GG 17 4 (0-155)

A 403 1 (0-119) 0.41 1.40 (0.83-2.37) 1.96 (1.13-3.41) 1.25 (0.74-2.11) 1.05 (0.59-1.88)
G 17 4 (0-155)
rs1746048 10 CXCL12 C/T 0.84 1.33 (1.20-1.48) 6,8,10

chemokine (C-X-C motif) ligand 12 CC 306 3 (0-128) 0.34 1.45 (0.86-2.44) 1.97 (1.14-3.40) 1.33 (0.79-2.23) 1.05 (0.59-1.88)
intragenic CT 100 0 (0-105)
TT 19 4 (0-155)

C 406 1 (0-120) 0.53 0.84 (0.39-1.84) 1.23 (0.56-2.71) 0.90 (0.42-1.95) 1.23 (0.53-2.86)
T 19 4 (0-155)
rs2047009 10 CXCL12 C/A 0.30 1.05 6

chemokine (C-X-C motif) ligand 12 CC 13 44 (0-167) 0.58 - - - -
intragenic AC 61 0 (0-111)
AA 73 13 (0-222)

C 74 0 (0-121) 0.07 - - - -
A 73 13 (0-222)
rs2505083 10 KIAA1462 C/T 0.23 1.07 (1.04-1.09) 20

KIAA1462 CC 5 0 (0-104) 0.69 - - - -
intron CT 23 1 (0-129)
TT 44 9 (0-357)

C 28 1 (0-116) 0.21 - - - -
T 44 9 (0-357)
rs2246833 10 LIPA T/C 0.16 1.04 6

lipase A, lysosomal acid, cholesterol esterase TT 1 0 (0-0) 0.27 - - - -
intron TC 5 5 (0-110)
CC 16 22 (1-338)

T 6 2 (0-110) 0.26 - - - -
C 16 22 (1-338)
rs1412444 10 LIPA T/C 0.20 1.09 (1.07-1.12) 11

lipase A, lysosomal acid, cholesterol esterase TT 2 0 (0-0) 0.10 - - - -
intron TC 5 5 (0-110)
CC 16 22 (1-338)

T 7 0 (0-110) 0.15 - - - -
C 16 22 (1-338)
rs11203042 10 LIPA T/C 0.31 1.03 6

lipase A, lysosomal acid, cholesterol esterase TT 2 254 (0-508) 0.82 - - - -
intron TC 6 7 (0-66)
CC 8 63 (2-114)

T 8 7 (0-88) 0.44 - - - -
C 8 63 (2-114)
rs1075724 10 MIKI67 G/A 0.21 1.78 (1.45-2.18) 21

antigen identified by monoclonal antibody Ki-67 GG 0 - - - - - -
intergenic AG 25 5 (0-214)
AA 34 63 (2-114)

G 25 5 (0-214) 0.65 - - - -
A 34 63 (2-114)
rs974819 11 PDGFD A/G 0.31 1.07 (1.04-1.09) 11

platelet derived growth factor D AA 2 0 0.38 - - - -
intergenic AG 1 34 (0-175)
GG 5 0

A 3 0 (0-175) - - - - -
G 5 0
rs964184 11 ZPR1 G/C 0.15 1.13 (1.10–1.16) 6,10

zinc finger protein 259 GG 9 4 (0-175) 0.34 1.00 (0.59-1.69) 0.86 (0.50-1.46) 0.86 (0.52-1.42) 0.96 (0.54-1.69)
intergenic CG 110 5 (0-197)
CC 306 1 (0-93)

G 119 5 (0-197) 0.08 0.89 (0.37-2.12) 1.16 (0.48-2.81) 0.93 (0.39-2.23) 1.00 (0.41-2.47)
C 306 1 (0-93)
rs9326246 11 ZPR1 C/G 0.06 1.04 6

zinc finger protein 259 CC 1 175 0.43 1.06 (0.56-1.99) 1.36 (0.72-2.59) 1.44 (0.79-2.65) 1.29 (0.67-2.49)
intergenic CG 49 28 (0-227)
GG 365 1 (0-114)

C 50 31 (0-207) 0.11 - - - -
G 365 1 (0-114)
rs17676451 12 HAL A/G 0.12 -0.17 (0.04)* 7

histidine ammonia lyase AA 2 157 (34-279) 0.25 2.06 (1.05-4.05) 2.03 (1-03-3.99) 1.98 (1.02-3.85) 1.33 (1.57-2.77)
intronic AG 41 48 (0-175)
GG 141 0 (0-54)

A 43 48 (0-185) 0.00 1.28 (0.51-3.25) 1.36 (0.54-3.47) 1.35 (0.53-3.43) 1.15 (0.45-2.97)
G 141 0 (0-54)
rs7136259 12 ATP2B1 T/C 0.48 1.11 (1-08-1.15) 12

ATPase, Ca++ transporting, plasma membrane 1 TT 13 150 (5-393) 0.06 - - - -
intronic TC 30 0 (0-198)
CC 15 18 (0-166)

T 43 11 (0-257) 0.77 - - - -
C 15 18 (0-166)
rs11066015 12 ACAD10 A/G 0.01 1.41 20,22

acyl-CoA dehydrogenase family, member 10 AA 0 - - 1.05 (0.42-2.63) 0.91 (0.35-2.34) 1.08 (0.43-2.71) 0.91 (0.35-2.34)
intronic AG 6 1 (0-332)
GG 418 2 (0-121)

A 6 1 (0-332) 0.87 - - - -
G 418 2 (0-121)
rs4773144 13 COL4A2 G/A 0.43 1.07 (1.05-1.09) 6,10

collagen, type IV, alpha 2 GG 80 3 (0-155) 0.47 1.50 (0.85-2.67) 1.68 (0.94-3.01) 1.70 (0.99-2.95) 1.63 (0.90-2.96)
intronic GA 201 2 (0-108)
AA 141 0 (0-123)

G 281 2 (0-116) 0.63 1.44 (0.86-2.39) 1.28 (0.75-2.17) 1.42 (0.85-2.36) 1.26 (0.71-2.24)
A 141 0 (0-123)
rs9515203 13 COL4A2 T/C 0.96 1.08 6,11

collagen, type IV, alpha 2 TT 68 0 (0-91) 0.04 - - - -
intronic TC 6 38 (31-348)
CC 0 -

T 74 2 (0-98) - - - - -
C 0 -
rs3809346 13 COL4A2 A/G 0.43 0.15 (0.03)* 7

collagen, type IV, alpha2 AA 80 3 (0-155) 0.48 1.43 (0.86-2.37) 1.27 (0.75-2.15) 1.40 (0.84-2.32) 1.28 (0.72-2.28)
intronic AG 201 2 (0-108)
GG 142 0 (0-122)

A 281 2 (0-116) 0.66 1.50 (0.84-2.66) 1.67 (0.93-3.01) 1.70 (0.98-2.94) 1.64 (0.91-2.98)
G 142 0 (0-122)
rs9319428 13 FLT1 A/G 0.30 1.05 (1.03-1.08) 6

fms-related tyrosine kinase 1 AA 37 0 (0-104) 0.45 1.07 (0.66-1.73) 1.29 (0.78-2.12) 1.15 (0.71-1.84) 1.23 (0.72-2.10)
intronic AG 173 4 (0-123)
GG 208 1 (0-123)

A 210 3 (0-119) 0.92 0.72 (0.35-1.45) 0.76 (0.37-1.55) 0.75 (0.37-1.51) 0.94 (0.45-1.97)
G 208 1 (0-123)
rs8001186 13 IRS2 A/G 0.36 -0.15 (0.03)* 7

insulin receptor substrate 2 AA 8 65 (1-169) 0.64 - - - -
intronic AG 17 34 (0-115)
GG 21 3 (0-311)

A 25 34 (0-135) 0.77 - - - -
G 21 3 (0-311)
rs7173743 15 ADAMTS7 LOC105370915 T/C 0.54 1.06 6

(ADAM metallopeptidase with thrombospondin type 1 motif, 7) LOC105370915 TT 112 1 (0-128) 0.72 1.01 (0.59-1.71) 1.02 (0.60-1.75) 1.25 (0.75-2.07) 1.08 (0.61-1.91)
intragenic CT 235 1 (0-105)
CC 78 5 (0-128)

T 347 1 (0-117) 0.32 1.73 (0.32-1.03) 0.94 (0.43-1.39) 0.91 (0.45-1.38) 0.82 (0.52-1.83)
C 78 5 (0-128)
rs17514846 15 FURIN A/C 0.48 1.05 (1.03-1.08) 6

furin (paired basic amino acid cleaving enzyme) AA 96 0 (0-128) 0.16 1.05 (0.61-1.83) 0.94 (0.54-1.64) 0.80 (0.47-1.36) 0.88 (0.48-1.58)
intronic AC 156 5 (0-105)
CC 107 3 (0-129)

A 252 1 (0-111) 0.36 1.15 (0.47-1.41) 0.86 (0.39-1.19) 1.30 (0.60-1.75) 1.16 (0.65-2.15)
C 107 3 (0-129)
rs3825807 15 ADAMTS7 A/G 0.60 1.08 (1.06–1.10) 6,10

ADAM metallopeptidase with thrombospondin type 1 motif, 7 AA 155 1 (0-119) 0.84 0.84 (0.47-1.51) 1.11 (0.61-2.03) 1.16 (0.64-2.08) 0.76 (0.40-1.43)
exon GA 202 2 (0-123)
GG 68 2 (0-121)

A 357 2 (0-121) 0.88 1.33 (0.64-1.75) 1.32 (0.59-1.65) 1.36 (0.63-1.66) 0.97 (0.42-1.28)
G 68 2 (0-121)
rs4380028 15 ADAMTS7 C/T 0.63 1.07 (1.05–1.10) 11,23

ADAM metallopeptidase with thrombospondin type 1 motif, 7 CC 162 2 (0-129) 0.61 0.79 (0.41-1.51) 0.96 (0.50-1.86) 0.90 (0.48-1.70) 0.82 (0.41-1.62)
exon TC 212 1 (0-91)
TT 51 5 (0-150)

C 374 1 (0-116) 0.36 1.06 (0.65-1.73) 0.95 (0.58-1.58) 1.09 (0.68-1.75) 0.94 (0.55-1.61)
T 51 5 (0-150)
rs12936587 17 RAI1 G/A 0.69 1.07 (1.05–1.09) 6,10

retinoic acid induced 1 GG 97 4 (0-81) 0.32 1.24 (0.66-2.32) 0.88 (0.48-1.63) 0.69 (0.38-1.28) 0.91 (0.47-1.77)
intragenic AG 92 17 (0-250)
AA 17 0 (0-64)

G 189 5 (0-129) 0.16 1.08 (0.48-2.44) 1.39 (0.61-3.16) 0.92 (0.41-2.08) 1.51 (0.64-3.6)
A 17 0 (0-64)
rs2281727 17 SMG6 C/T 0.32 1.04 11

smg-6 homolog, nonsense mediated mRNA decay factor LOC105371487 CC 36 0 (0-28) 0.28 0.83 (0.41-1.66) 0.67 (0.33-1.39) 0.81 (0.40-1.65) 0.86 (0.40-1.85)
RNA anitsense CT 144 0 (0-129)
TT 161 3 (0-197)

C 180 0 (0-105) 0.18 0.76 (0.45-1.27) 0.77 (0.45-1.32) 0.67 (0.4-1.12) 0.72 (0.4-1.27)
T 161 3 (0-197)
rs1231206 17 SMG6 A/G 0.30 1.07 (1.05-1.09) 6

smg-6 homolog, nonsense mediated mRNA decay factor AA 30 0 (0-23) 0.30 0.81 (0.48-1.37) 0.80 (0.46-1.38) 0.75 (0.44-1.26) 0.77 (0.43-1.37)
RNA anitsense AG 134 0 (0-129)
GG 161 3 (0-197)

A 164 0 (0-114) 0.22 1.14 (0.49-2.08) 1.01 (0.37-1.63) 1.12 (0.44-1.92) 1.09 (0.43-2.04)
G 161 3 (0-197)
rs216172 17 SMG6 C/G 0.29 1.07 (1.05–1.09) 10

smg-6 homolog, nonsense mediated mRNA decay factor CC 30 0 (0-18) 0.24 0.85 (0.50-1.43) 0.81 (0.47-1.39) 0.76 (0.45-1.28) 0.81 (0.46-1.44)
RNA anitsense CG 132 0 (0-129)
GG 164 2 (0-189)

C 162 0 (0-114) 0.25 0.91 (0.45-1.86) 0.71 (0.34-1.48) 0.85 (0.41-1.76) 0.91 (0.42-1.99)
G 164 2 (0-189)
rs15563 17 UBE2Z C/T 0.53 1.01 (0.99-1.03) 6

ubiquitin-conjugating enzyme E2Z CC 36 0 (0-46) 0.68 - - - -
exon CT 47 0 (0-41)
TT 29 1 (0-105)

C 83 0 (0-43) 0.26 - - - -
T 29 1 (0-105)
rs46522 17 UBE2Z T/C 0.53 1.06 (1.04–1.08) 6,10

ubiquitin-conjugating enzyme E2Z TT 36 0 (0-46) 0.64 - - - -
intron CT 46 0 (0-43)
CC 29 1(0-105)

T 82 0 (0-43) 0.28 - - - -
C 29 1 (0-105)
rs1122608 19 SMARCA4 G/T 0.78 1.14 (1.09–1.18) 6,8,10

SWI/SNF related, matrix associated, actin dependent regulator of chromatin, subfamily a, member 4 GG 260 1 (0-121) 0.44 0.71 (0.43-1.16) 0.89 (0.54-1.47) 0.71 (0.44-1.15) 0.83 (0.48-1.42)
intron GT 139 3 (0-147)
TT 24 1(0-66)

G 399 2 (0-129) 0.65 0.71 (0.35-1.46) 0.77 (0.37-1.59) 0.66 (0.33-1.33) 1.05 (0.48-2.28)
T 24 1(0-66)
rs2228671 19 LDLR C/T 0.94 1.09 (1.02-1.15) 11

low density lipoprotein receptor CC 307 0 (0-121) 0.03 - - - -
exon TC 42 35 (0-129)
TT 1 0

C 349 2 (0-128) - 0.55 (0.28-1.07) 0.63 (0.32-1.23) 0.54 (0.29-1.03) 0.48 (0.25-0.94)
T 0 0
rs2075650 19 TOMM40 G/A 0.14 1.11 6

translocase of outer mitochondrial membrane 40 homolog GG 8 8 (1-262) 0.43 1.49 (0.63-3.50) 1.18 (0.50-2.80) 1.20 (0.51-2.84) 1.49 (0.62-3.60)
intron GA 99 4 (0-148)
AA 317 1 (0-116)

G 107 4 (0-153) 0.18 1.66 (0.97-2.83) 1.20 (0.70-2.06) 1.03 (0.62-1.73) 1.07 (0.60-1.89)
A 317 1 (0-116)
rs9982601 21 KCNE2 T/C 0.03 1.19 (1.13–1.27) 6,8,10

potassium channel, voltage gated subfamily E regulatory beta subunit 2 TT 0 - - - - - -
intergenic TC 14 66 (0-129)
CC 206 1 (0-115)

T 14 66 (0-129) 0.15 1.43 (0.63-3.26) 1.60 (0.70-3.64) 1.46 (0.65-3.29) 1.19 (0.52-2.74)
C 206 1 (0-115)
rs7278204 21 KCNE2 G/A 0.02 1.09 (1.03-1.15) 11

potassium channel, voltage gated subfamily E regulatory beta subunit 2 GG 0 - - - - - -
intergenic GA 9 79 (0-171)
AA 215 1 (0-115)

G 9 79 (0-171) 0.36 1.35 (0.57-3.21) 1.51(0.64-3.56) 1.28 (0.54-3.02) 1.39 (0.58-3.32)
A 215 1 (0-115)

CAC is expressed as median (25p-75p). ‘p’ values represent U-Mann Whitney test for the comparison of homozygous for the effect allele versus heterozygous (upper row) and the comparison of the effect allele vs. the non-effect.

Logistic regression analysis (odds ratios, OR -95% confidence interval-) adjusted for traditional cardiovascular risk factors (age, sex, diabetes, hypertension, dyslipidemia, and smoking) express the relation of homozygous against heterozygous, or for the relation of affected allele against the non affected, with CAC expressed as higher than 0 and 10 units or higher than 70th and 90th percentiles.

Effect allele and homozygous forms, and significant p values, are depicted in bold.

*

Refers to beta coefficient (standard error).

Results

Demographic, laboratory, and clinical characteristics

The clinical characteristics of the patients in the three cohorts are presented in Table 1. Average age across the three cohorts was 57.6 ± 10.5 years old, 77% of the patients were women and 89% of the patients were Caucasian. Cardiovascular comorbidity was not different between groups except for a higher prevalence of hypertension, current smoking, and aspirin intake in the Vanderbilt cohort, where patients with previously known CVD were allowed to enroll. There were no differences between cohorts regarding CAC Agatston score. Median CAC score was 3.12 (interquartile range 0-134.35) in the three cohorts, and 21% and 35% of the patients had a CAC score greater than the 90th and 75th percentile, respectively. RA disease duration was 10 (interquartile range 3-20) years, 44% of the patients were receiving corticosteroid treatment, 32% were receiving anti-TNF therapy, and 65% were seropositive for rheumatoid factor.

Table 1. Demographic and clinical data of rheumatoid arthritis patients in the three cohorts.

Total (n=561) Cohorts


ESCAPE (n=197) Pittsburgh (n=195) Vanderbilt (n=169)

Demographics

 Age, years 57.6 ± 10.5 59.4 ± 8.7 58.8 ± 10.2 54.2 ± 11.8
 Sex, female(%) 430 (77) 118 (60) 195 (100) 117 (69)
 BMI, kg/m2 28.5 ± 6.0 28.3 ± 5.3 27.9 ± 6.0 29.2 ± 6.8
 Hip circumference, cm
  Female 106.7 ± 14.8 105.5 ± 14.6 105.9 ± 14.3 109.4 ± 15.6
  Male 103.0 ± 12.3 100.6 ± 10.7 - 106.7 ± 13.6
 Waist circumference, cm
  Female 91.9 ± 16.4 91.7 ± 15.6 91.2 ± 16.7 93.1 ± 16.8
  Male 101.4 ± 14.9 101.6 ± 13.3 - 101.1 ± 17.2
 Race
  White 502 (89) 169 (86) 184 (94) 149 (88)
  Others 57 (10) 28 (14) 10 (5) 19 (11)
Agatston score for CAC

 CAC Agatston units 3.12 (0-134.35) 4.69 (0-175.00) 2.75 (0-93.37) 1.85 (0-150.35)
 CAC greater than 0 units, n(%) 307 (55) 107 (55) 117 (60) 83 (51)
 CAC greater than 10 units, n(%) 248 (49) 90 (46) 86 (44) 72 (44)
 CAC greater than percentile 75, n(%) 195 (35) 63 (32) 75 (39) 57 (35)
 CAC greater than percentile 90, n(%) 113 (21) 36 (18) 39 (20) 38 (23)
Previous cardiovascular disease

 Cardiovascular events, n(%) 61 (11) 0 (0) 21 (11) 40 (24)
Comorbidity

 Hypertension, n(%) 235 (42) 76 (38) 71 (36) 88 (52)
 Systolic blood pressure, mmHg 129 ± 20 128 ± 19 125 ± 19 133 ± 20
 Diastolic blood pressure, mmHg 76 ± 10 76 ± 9 76 ± 10 75 ± 11
 Use of antihypertensives, n(%) 210 (37) 79 (40) 67 (34) 64 (38)
 Dyslipemia 119 (21) 62 (31) 57 (29) 81 (48)
  On lipid lowering drugs 60 (11) 35 (18) 25 (13) 19 (12)
 Diabetes 22 (4) 12 (6) 10 (5) 17 (10)
 Previous smoking 291 (52) 115 (58) 96 (49) 80 (47)
 Current smoking 81 (14) 23 (12) 17 (9) 41 (24)
  Packs/years 0 (0-22) 7 (0-30) 0 (0-14) 0 (0-22)
 Postmenopause 249 (44) 92 (47) 157 (81) 74 (47)
 Hormone replacement use 85 (15) 16 (8) 69 (35) -
 Metabolic syndrome 90 (16) 44 (22) 46 (24) 55 (36)
 Aspirin 102 (18) 34 (17) 14 (7) 54 (32)
Analytical parameters

 Total cholesterol, mg/dL 197 ± 39 195 ± 38 208 ± 37 186 ± 39
 Triglycerides, mg/dL 1116 (86-157) - 120 (90-156) 111 (80-158)
 HDL cholesterol, mg/dL 54 ± 16 49 (41-67) 61 ± 15 43 (37-54)
 LDL cholesterol, mg/dL 116 ± 33 116 ± 31 120 ± 35 112 ± 33
 Glucose, mg/dL 91 ± 19 89 (83-98) 88 (82-94) 87 (83-94)
 Insulin, μU/mL 10 ± 7 6 (4-10) 12 (9-14) 10 (5-19)
 Homocysteine, μmol/L 10.7 ± 3.6 9.1 (7.5-10.6) 11.1 (9.6-13.7) 10.5 ± 3.4
 Creatinine, mg/dL 0.8 ± 0.3 0.8 ± 0.2 0.9 ± 0.3 0.8 ± 0.2
 CRP, mg/L 4.65 (1.75-12.50) - 5.62 (1.97-13.35) 4.00 (1.22-13.02)
Rheumatoid arthritis

 Disease duration, years 10 (3-20) 9 (4-17) 13 (7-23) 3 (2-18)
 Prednisone
  Ever prednisone treatment 458 (82) 147 (75) 172 (88) 139 (82)
  Current with prednisone 246 (44) 76 (39) 78 (40) 92 (54)
  Current pred. dosage, mg/day 0 (0-5) 0 (0-5) 0 (0-5) 2 (0-5)
 Hydroxycloroquine 125 (22) 47 (24) 36 (18) 42 (25)
 Methotrexate 360 (64) 125 (63) 115 (59) 120 (71)
 TNF inhibitors 179 (32) 85 (43) 59 (30) 35 (21)
 Anakinra 2 (0) 1 (1) 1 (1) 0 (0)
 NSAIDs 313 (73) 127 (64) 135 (69) 51 (30)
 COX2 inhibitors 154 (72) 47 (24) 56 (29) 51 (30)
 Minutes of morning stiffness 30 (5-60) 15 (5-30) 30 (0-60) 30 (10-90)
 Current biologic DMARD use 149 (27) 89 (45) 60 (31) 32 (19)
 Any current use of non-biologic DMARDs 487 (87) 165 (84) 175 (90) 147 (87)
 Joint surgery 156 (28) 55 (28) 101 (52) -
 Rheumatoid nodules 197 (35) 89 (45) 108 (55) -
 Global ass. of disease activity 24 (9-47) 21 (5-47) 19 (6-34) 30 (16-55)
 MModified HAQ (VU cohort only) 0.500 (0.000-0.875) 0.500 (0.000-0.875)
 DAS28 (ESCAPE and VU cohorts) 3.72 ± 1.35 3.66 ± 1.08 - 3.79 ± 1.61
 Full HAQ (ESCAPE cohort only) 0.625 (0.125-1.250) 0.625 (0.125-1.250) - -
 RF (>40 units) 363 (65) 129 (65) 117 (60) 117 (69)

Data expressed as mean (± standard deviation) or median (interquartile range). Dichotomous variables are expressed as number (percentage).

CRP=C reactive protein; HAQ=Health Assessment Questionnaire; DAS28=Disease Activity Score; HDL=High density lipoprotein; LDL=Low density lipoprotein.

DMARD=Disease-modifying Antirheumatic Drug; TNF=tumor necrosis factor; COX-2=cyclooxygenase-2

Modified HAQ is only available for Vanderbilt cohort. DAS28 only for ESCAPE and Vanderbilt coh ort. Full HAQ only in ESCAPE series.

CAC -coronary artery calcification- percentiles were adjusted for age and race as previously described

Coronary artery disease related SNPs in relation to RA CAC

Table 2 shows the relation of the 91 SNPS related to CAD in the general population to the presence of CAC in the RA cohort. 86 of these SNPs did not exhibit any positive association with CAC in the RA cohort, either considering the affected versus the non-affected allele in homozygous or heterozygous inheritance with the Agatston score as a continuous variable, or in the association analysis using CAC categorizations. Only rs646776 (CELSR2), rs602633 (PSCR1), rs579459 (ABO), rs501120 (CXCL12) and rs17676451 (HAL) expressed any positive relation with CAC in one or more of the analyses. rs579459 (ABO) and rs17676451 (HAL) genotype exhibited the most consistent association between genotype and CAC Agatston units, with a significant increase in the frequency of the effect alleles in both homozygous or heterozygous genotype distributions, however, in the case of ABO, CAC categorizations, although demonstrating trends to significance, were not significantly associated. The positive associations for the other three SNPs were much less consistent, e.g. for rs501120 (CXCL12) there was no association of homozygous or heterozygous genotype distribution with CAC Agatston units, however in heterozygotes there was a positive association with the effect allele A in higher than 10 units CAC categorization (odds ratio 1.96 [1.13-3.41)]), although there was no association of any CAC categorizations with the homozygous AA genotype, which would be expected to be more sensitive (Table 2).

Notably, none of the group of the 12 SNPs mapping in the 53 kb region of chromosome 9p21.3, encoding ANRIL that are among the strongest predictors of CAD in the general population exhibited any association with CAD. Moreover, in the instance of PHACTR1, also strongly positively associated with CAD risk in the general population, three SNPs (rs9369640, rs12526453, and rs1332844) consistently showed a limited and incomplete protective relation with CAC. E.g., in the case of rs1332844, the p value for a homozygous or heterozygous mode of inheritance was respectively 0.01 and 0.08. Additionally COL4A2 (rs9515203) and LDLR (rs2228671) were negatively associated with CAC in the homozygous mode of inheritance.

Number of homozygous SNPs in relation to RA CAC

When the association of the CAD related SNPS with CAC was studied through the non weighted and weighted set of SNPs, no significant association was found. In particular, an increase in the number of both homozygous or heterozygous cardiovascular disease related SNPs was not significantly associated with an increase in log CAC Agatston units (Figure 1, panel A). Correspondingly, CAC categorizations in CAC higher than 0 and 10 units, and higher than 75th and 90 percentiles did not exhibit an increased frequency of homozygous or heterozygous SNPs (Figure 1, panel B).

Figure 1.

Figure 1

Panel A shows log coronary artery calcification (CAC) (mean and standard deviation -SD- Agatston units, right axis) relation with number of coronary artery disease related SNPs (left axis). Panel B shows number of CAD related SNPs (Tukey's bloxplots) in every CAC categorization - CAC higher than 0 and 10 Agatston units and higher than percentile 75th and 90th; ‘p’ values of the difference in every categorization is showed. Panel C depicts a trend analysis of log CAC (mean and SD) and its relation with the weighted genetic risk score.

Additionally, when CAD related SNPs were weighted by their effect sizes, the resulting GRS was not significantly associated with CAC. Furthermore, trend analysis showed no relation between GRS and log CAC Agatson units (p=0.93) (Figure 1, panel C).

Genetic risk score, disease activity, and CAC

The relationship between CAC and GRS or disease activity is illustrated in Table 3 through the value of the beta coefficient, which reflects the change in GRS as a function of the change in CAC categorizations. All the categorizations of CAC were associated with higher disease activity scores (DAS 28) after adjusting for age and sex. When this analysis was performed adjusting for traditional cardiovascular risk factors like diabetes, dyslipidemia, hypertension and smoking this relation was maintained in higher than CAC 90th percentile patients (beta coefficient 0.43 [0.04-0.81], p=0.03) and was nearly significant in both patients with CAC higher than 10 Agatston units (beta coef. 0.34 [-0.01-0.68], p=0.06) or patients within the CAC 75th percentile (beta coef. 0.28 [-0.05-0.60], p=0.09).

Table 3. Coronary artery calcification relation with disease activity score and genetic risk score.

DAS28 (beta coef. 95% CI, p)

Unadjusted Model #1 Model #2 Model #3
Univariate model Adjusted for age and sex Adjusted for Model 1 plus diabetes, hypertension, smoking and dyslipidemia Adjusted for Model 1 and 2 plus GRS

CAC > 0 0.15 (-0.13-0.43), 0.30 0.37 (0.04-0.70), 0.03 0.09 (-0.27-0.45), 0.62 0.08 (-0.28-0.44), 0.65
CAC > 10 0.24 (-0.04-0.52), 0.09 0.48 (0.16-0.80), 0.00 0.34 (-0.01-0.68), 0.06 0.32 (-0.02-0.68), 0.07
CAC > 75th 0.39 (0.10-0.68), 0.01 0.46 (0.16-0.76), 0.00 0.28 (-0.05-0.60), 0.09 0.27 (-0.06-0.59), 0.10
CAC > 90th 0.52 (0.18-0.86), 0.00 0.55 (0.21-0.89), 0.00 0.43 (0.04-0.81), 0.03 0.42 (0.04-0.81), 0.03

Genetic risk score (beta coef. 95% CI, p)
Unadjusted Model #1 Model #2

Univariate model Adjusted for age and sex Adjusted for Model 1 plus diabetes, hypertension, smoking and dyslipidemia

CAC > 0 - 0.03 (-0.06--0.00), 0.03 -0.01 (-0.04-0.02), 0.51 -0.01 (-0.05-0.03), 0.66
CAC > 10 - 0.04 (-0.06--0.01), 0.04 -0.01 (-0.04-0.03), 0.68 -0.01 (-0.04-0.04), 0.95
CAC > 75th - 0.01 (-0.04-0.02), 0.59 0.00 (-0.03-0.03), 0.91 0.01 (-0.03-0.05), 0.72
CAC > 90th 0.01 (-0.03-0.04), 0.69 0.01 (-0.03-0.05), 0.57 0.02 (-0.03-0.06), 0.50

CAC = coronary artery calcification; CI = confidence interval

Conversely, GRS was inversely associated with CAC higher than 0 (- 0.03 [-0.06--0.00], 0.03) and higher than 10 Agatston units (- 0.04 [-0.06--0.01], 0.04) (Table 3). However, in the multivariate analysis, after adjusting for age and sex and for traditional cardiovascular factors, GRS was not related with CAC. In this sense, patients within CAC 90th percentile did not exhibit higher levels of GRS even after multivariate analysis (beta coef. 0.02 [-0.03-0.06], p=0.50).

Similarly, the relation between CAC and DAS28 was not modified when the analysis was adjusted for GRS (Model 3). In this regard, when we evaluated the association between CAC 90th percentile patients and DAS28 for the contribution of GRS, the statistically significant association (beta coef. 0.42 [0.04-0.81], p=0.03) between CAC and DAS28, was maintained in this set of patients, and was not modified by GRS.

Discussion

The central finding of our study is that RA patients with CAC, compared to those without CAC do not exhibit the elevated frequency of the multiple CAD specific SNPs found at increased frequency among patients in the general population with CAD. This finding suggests that CAC in RA does not develop through the concerted action of the same genes and their related pathways implicated with the development of CAD in the general population. The lack of contribution of these proatherosclerotic genes implies that RA itself should be considered an independent cardiovascular risk factor. Accordingly, we suggest that some factor in the RA immune response primarily contributes to the increased prevalence and incidence of cardiovascular disease in RA through pathways distinct from the proatherosclerotic pathways that operate in the general population to cause CAD.

Cardiovascular disease has an estimated heritability in the general population of 30–60% and genome-wide association studies have identified SNPs at several genomic regions associated with atherosclerosis, CAD and the progression to myocardial infarction (4-24, 47). However, the role of these CAD SNPs known to be related with cardiovascular disease in general population has not been previously explored in RA patients. In this study we used CAC as a complex cardiovascular trait related with CAD. The use of CAC as a validated CAD equivalent is supported by its ability to predict incident coronary heart disease even after adjustment for traditional cardiovascular risk factors (27).

Because each individual genetic variant specified by a SNP explains a small fraction of the variation in a complex trait and thus has limited predictive capacity for disease risk (48), we also constructed a weighted GRS with all the CAD related SNPs. GRSs are one of the most promising ways to aggregate multiple sets of SNP results into a single genetic predictor, and have been previously applied to different cardiovascular traits in the literature (49). Although still under development (49), they have been successfully used to predict cardiovascular outcomes and intermediate traits or subclinical phenotypes, including coronary heart/artery disease (50), myocardial infarction (51), ischemic stroke (52), or hypertension (53).

We note that we had the power to detect an association with an effect size of 0.1 at an alpha of 0.05. However, the observed effect sizes were much lower if not negligible. For example, if we sought to detect an association of 0.5% (that could be considered clearly insignificant) we would need a sample size of 1731. Moreover, the positive association with the ABO SNP supports the notion that this study was sufficiently powered to detect associations of CAD SNPs to confer susceptibility if they were present. Therefore, it is appropriate to infer that the CAD SNPs are unlikely to be a significant source of variability for CAC in RA patients. The ABO locus encodes glyco-transferases that when absent in blood group O individuals protect against myocardial infarction (24), although their relation to CAC in RA patients suggests they may foster CAC development in this setting by mechanisms that differ from those in individuals without RA.

The interpretation that factors intrinsic to RA independently contribute to CAC is supported by the finding that CAC is clearly related to disease activity through the DAS28 score. Indeed the increased DAS28 scores in those with higher CAC remained significant even after adjusting for traditional cardiovascular risk factors, as well as by the GRS for alleles influencing CAD in the general population.

Similarly, one immunological mechanism in RA unrelated to CAD SNPs that could potentially contribute to the association is that CAC in RA patients is significantly and independently associated with an elevated percentage of circulating CD28-CD57+CD56+ memory effector CD4 T cells, and with an increased proportion of the CD14hiCD16+ monocyte subset bearing an intermediate or ‘inflammatory’ phenotype (54). These elevated numbers of memory effector T cell and inflammatory monocyte subsets, which are considered an intrinsic element in the immune response mediating RA, may also provision the nascent and clinically unimportant subintimal lipid deposits with effector T cells and inflammatory monocytes that could accelerate the development of advanced atherosclerotic vascular disease.

Additionally, several studies (55) support the association of polymorphic genes involved in influencing RA susceptibility or the severity of effector pathways of RA with cardiovascular disease. These include the association between alleles encoding the HLA-DR shared epitope with both subclinical and clinically evident CV disease (56), and variants belonging to genes implicated in inflammatory and metabolic pathways, such as rs1800629 (TNFA), rs909253 (LTA), rs1800795 (IL6), rs333 (CCR5), rs2812378 (CCL21), and rs1800470 (TGFB1), which have been associated with a higher risk of endothelial dysfunction, different types of cardiovascular events, and cardiovascular mortality in RA (55, 57-60).

There are some limitations in this study. First, this study should be considered exploratory because the experimental design does not include a validation cohort. Second, although genotyping was facilitated in our study because a considerable proportion of CAD SNPs were fortuitously present on the Immunochip, the studies exploring susceptibility for CAD in the general population utilized different chips, most notably the Metabolic chip, each of which has a different spectrum of SNPs. Therefore we had to use imputation to identify some important polymorphisms, which is still an evolving approach (41). Third, CAC appears at an intermediate stage in the development of atherosclerosis and the assessment of earlier stages of atherosclerosis may prove more sensitive, as would adding the later stage of a myocardial event. Fourth, the association observed between DAS28 and CAC could also be influenced by non-inflammatory comorbidities, such as depression, fibromyalgia, osteoarthritis, etc. that can also lead to higher DAS28 scores.

The role of genetic factors in accelerated cardiovascular disease in RA requires further study to better identify the mechanisms and pathways responsible for this association. To our knowledge, this is the first investigation in which general population CAD related SNPs has been assessed in a large set of RA patients with a reproducible, sensitive, quantitative measure of CAD. Our findings of an absence of association of these CAD related SNPs with CAC in RA is novel and could shed light on the complicated relationship between inflammation and cardiovascular risk in RA patients. In conclusion, we have shown that in RA, even when using all known genetic susceptibility variants associated with CAD in the general population, gene dosage of these susceptible CAD SNPs was not associated with the increased CAC observed in patients. Our findings would support the role of one or more mechanistic features in RA itself as the fundamental responsible factor for the increase of cardiovascular diseases in RA.

Supplementary Material

Supp TableS1

Acknowledgments

We thank Angela Christiano, PhD, and her laboratory for the extraction of DNA in many of the samples.

Financial support: This work was supported by the National Institute of Arthritis and Musculoskeletal and Skin Diseases grant AR-050026 (Dr. Bathon), AR056116 (Dr. Stein), a Pfizer ASPIRE Investigator Initiated Rheumatology Award WI195003 (Dr. Winchester), the NIH National Center for Advancing Translational Sciences grant UL1-TR-000040 [formerly the National Center for Research Resources, grant UL1-RR-024156], and CTSA award No. UL1TR000445 from the National Center for Advancing Translational Sciences; K01AR060848 (Dr. Reynolds); National Institute of Arthritis and Musculoskeletal and Skin Diseases (K23AR064768) and the Rheumatology Research Foundation Career Development K Supplement (Chung); and by the Fundación Canaria Dr. Manuel Morales, Fundación Española de Reumatología and Complejo Hospitalario Universitario de Canarias (Dr. Ferraz-Amaro).

Footnotes

Author contributions: All authors were involved in drafting the article or revising it critically for important intellectual content, and all authors approved the final version to be published. Dr. Ferraz-Amaro had full access to all of the data in the study and takes responsibility for the integrity of the data and the accuracy of the data analysis.

Study conception and design: Bathon, Winchester, Giles, Ferraz-Amaro, Reynolds, Gregersen.

Acquisition of data: Bathon, Giles, Stein, Wasko, Gregersen, Chung, Oeser.

Analysis and interpretation of data: Ferraz-Amaro, Winchester, Reynolds, Gregersen, Wasko, Stein, Giles, Bathon, Chung, Oeser.

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