The interaction of adiposity with the CRP gene affects CRP levels: age, gene/environment susceptibilty-Reykjavik study

Socioeconomic position interacts with the genetic effect of a CRP gene common variant to influence C-reactive protein values

OBJECTIVES

C-Reactive Protein (CRP) values are partly determined by variation at the CRP gene locus, but also influenced by socioeconomic position (SEP) and related lifestyle factors. As gene-by-SEP interactions have been suggested for traits associated with CRP and SEP (e.g., BMI, coronary artery disease), the aim of this study was to investigate the strength of a possible interaction between a CRP gene common variant (rs4287174) and SEP in their joint influence on CRP levels in a population-based study sample.

METHODS

Single nucleotide polymorphism rs4287174 was genotyped in 4065 participants (aged 45-75 years) of the Heinz Nixdorf Recall study, a population-based prospective cohort. SEP indicators (education and income), risk factors (i.e., body mass index (BMI), total cholesterol, diabetes mellitus, coronary artery calcification, current smoking, hypertension, diet, no exercise) and blood serum CRP (mg/dl) were assessed at study baseline. Interaction analysis was based on linear regression and on stratified analyses (genetic effect stratified by SEP and vice versa) adjusted for age and sex using loge(CRP + 1) as dependent variable.

RESULTS

Low SEP and rs4287174 T allele were both associated with higher CRP values. The strongest genetic effect was observed in the lowest educational group (≤ 10 years of education) with an exp(β) indicating 1.058-fold (95%-CI: 1.018; 1.100) average CRP values per additional T allele, while in the highest educational group (≥ 18 years) the association was considerably less strong (exp(β): 1.005 (95%-CI: 0.975; 1.037)). After including rs4287174-by-education interaction terms in the regression analysis, interaction was indicated suggesting stronger genetic effects on CRP in low SEP groups (exp(βinteraction): 1.056 (95%-CI: 1.005; 1.108); p = 0.029). The observed interaction did not seem to be substantially mediated by the risk factors included in the analysis. No indication for rs4287174-by-income interaction was observed.

CONCLUSION

Results imply that genetic effects of the CRP locus are modified by education as an indicator of life course SEP.

Rare functional variants in the CRP and G6PC genes modify the relationship between obesity and serum C-reactive protein in white British population

BACKGROUND

C-reactive protein (CRP) is a sensitive biomarker of inflammation with moderate heritability. The role of rare functional genetic variants in relation to serum CRP is understudied. We aimed to examine gene mutation burden of protein-altering (PA) and loss-of-function (LOF) variants in association with serum CRP, and to further explore the clinical relevance.

METHODS

We included 161,430 unrelated participants of European ancestry from the UK Biobank. Of the rare (minor allele frequency <0.1%) and functional variants, 1,776,249 PA and 266,226 LOF variants were identified. Gene-based burden tests, linear regressions, and logistic regressions were performed to identify the candidate mutations at the gene and variant levels, to estimate the potential interaction effect between the identified PA mutation and obesity, and to evaluate the relative risk of 16 CRP-associated diseases.

RESULTS

At the gene level, PA mutation burdens of the CRP (β = -0.685, p = 2.87e-28) and G6PC genes (β = 0.203, p = 1.50e-06) were associated with reduced and increased serum CRP concentration, respectively. At the variant level, seven PA alleles in the CRP gene decreased serum CRP, of which the per-allele effects were approximately three to seven times greater than that of a common variant in the same locus. The effects of obesity and central obesity on serum CRP concentration were smaller among the PA mutation carriers in the CRP (pinteraction  = 0.008) and G6PC gene (pinteraction  = 0.034) compared to the corresponding non-carriers.

CONCLUSION

PA mutation burdens in the CRP and G6PC genes are strongly associated with decreased serum CRP concentrations. As serum CRP and obesity are important predictors of cardiovascular risks in clinics, our observations suggest taking rare genetic factors into consideration might improve the delivery of precision medicine.

Association of - 717 A > G (rs2794521) CRP polymorphism with high cardiovascular risk by C-reactive protein in systemic lupus erythematosus patients

INTRODUCTION

Systemic lupus erythematosus (SLE) is an autoimmune disease where genetic factors have been related to SLE susceptibility and disease severity. CRP polymorphisms have been associated with high C-reactive protein (CRP) serum levels, cardiovascular disease (CVD), and high clinical disease activity in SLE patients; however, the evidence is still inconclusive.

OBJECTIVE

This study was aimed to assess the association of the - 717 A > G, - 409 G > A, + 1444 C > T, and + 1846 C > T CRP polymorphisms with genetic susceptibility, clinical disease activity, and CVD risk in Mexican-mestizo SLE patients.

METHODS

A comparative cross-sectional study was conducted on 369 unrelated women: 183 with SLE according to the 1997 SLE-ACR criteria and 186 healthy subjects (HS). The clinical disease activity was assessed by the Mex-SLEDAI score; CRP and lipid profile were quantified by turbidimetry and colorimetric-enzymatic assays, respectively. The CRP polymorphisms genotyping was carried out by allelic discrimination.

RESULTS

SLE patients with - 717 AA genotype had higher CRP serum levels than SLE carriers of AG and GG genotypes (AA = 5 mg/L vs. AG = 3.2 mg/L vs. GG = 2.4 mg/L; p = 0.01), and the AA genotype was associated with high CVD risk by CRP in SLE patients (OR = 3; CI: 1.2-7.6; p < 0.01).

CONCLUSIONS

The - 717 A > G CRP polymorphism is a risk factor for high CRP levels and high CVD risk in Mexican-mestizo SLE patients. Key Points • Cardiovascular disease is one of the major causes of death in SLE patients due to the higher prevalence of traditional and non-traditional cardiovascular risk factors. • C-reactive protein is a liver-derived acute-phase protein suggested as one powerful independent risk predictor factor for cardiovascular disease. • Single nucleotide polymorphisms in CRP have been suggested as genetic susceptibility factors that could modify the SLE pathophysiology outcomes. • Mexican-mestizo SLE patients carrying the -717 A>G CRP AA genotype had 3-fold high cardiovascular disease risk than SLE patients with AG or GG genotypes.

Quantile-dependent expressivity of serum C-reactive protein concentrations in family sets

BACKGROUND

"Quantile-dependent expressivity" occurs when the effect size of a genetic variant depends upon whether the phenotype (e.g., C-reactive protein, CRP) is high or low relative to its distribution. We have previously shown that the heritabilities (h 2) of coffee and alcohol consumption, postprandial lipemia, lipoproteins, leptin, adiponectin, adiposity, and pulmonary function are quantile-specific. Whether CRP heritability is quantile-specific is currently unknown.

METHODS

Serum CRP concentrations from 2,036 sibships and 6,144 offspring-parent pairs were analyzed from the Framingham Heart Study. Quantile-specific heritability from full-sib (βFS, h 2 ={(1 + 8rspouseβFS)0.5 - 1}/(2rspouse)) and offspring-parent regression slopes (βOP, h 2 = 2βOP/(1 + rspouse)) were estimated robustly by quantile regression with nonparametric significance determined from 1,000 bootstrap samples.

RESULTS

Quantile-specific h 2 (±SE) increased with increasing percentiles of the offspring's age- and sex-adjusted CRP distribution when estimated from βOP (P trend = 0.0004): 0.02 ± 0.01 at the 10th, 0.04 ± 0.01 at the 25th, 0.10 ± 0.02 at the 50th, 0.20 ± 0.05 at the 75th, and 0.33 ± 0.10 at the 90th percentile, and when estimated from βFS (P trend = 0.0008): 0.03±0.01 at the 10th, 0.06 ± 0.02 at the 25th, 0.14 ± 0.03 at the 50th, 0.24 ± 0.05 at the 75th, and 0.53 ± 0.21 at the 90th percentile.

CONCLUSION

Heritability of serum CRP concentration is quantile-specific, which may explain or contribute to the inflated CRP differences between CRP (rs1130864, rs1205, rs1800947, rs2794521, rs3091244), FGB (rs1800787), IL-6 (rs1800795, rs1800796), IL6R (rs8192284), TNF-α (rs1800629) and APOE genotypes following CABG surgery, stroke, TIA, curative esophagectomy, intensive periodontal therapy, or acute exercise; during acute coronary syndrome or Staphylococcus aureus bacteremia; or in patients with chronic rheumatoid arthritis, diabetes, peripheral arterial disease, ankylosing spondylitis, obesity or inflammatory bowel disease or who smoke.

Mediation effect of C-reactive protein in the relationship between abdominal obesity and intermediate hyperglycemia in Kuwaiti adolescents

Aim: This study aimed to investigate the mediating effect of C-reactive protein (CRP) on obesity and hyperglycemia. Materials & methods: Fasting blood glucose, high-sensitivity CRP (hs-CRP) levels and waist circumference (WC) were measured on 353 participants. Multilevel regression modeling and mediation analyses were used to investigate the link between abdominal obesity, hs-CRP and hyperglycemia. Results: Elevation in hs-CRP was predictive of hyperglycemia in nonobese individuals (OR = 1.3, p = 0.03). With every 1-mg/l increase in hs-CRP, there was a 1-cm increase in WC (B = 0.87, p = 0.001). hs-CRP was a full mediator in the relationship between WC and hyperglycemia. Conclusion: hs-CRP predicts hyperglycemia development in nonobese individuals and the effect of increased WC on hyperglycemia was fully mediated by hs-CRP.

C-reactive protein gene rs1205 polymorphism is associated with low-grade chronic inflammation in postmenopausal women

Background

Cardiovascular disease is the leading cause of death in postmenopausal women, and inflammation is a key mechanism involved in the pathogenesis of atherosclerosis. High-sensitivity C-reactive protein (hs-CRP) has been used as a biomarker of inflammation. Considering that CRP gene rs1205 polymorphism has been associated with hs-CRP circulating levels, we evaluated whether rs1205 genotypes influence the presence of low-grade chronic inflammation, acting as a marker of cardiovascular risk.

Methods

We performed a cross-sectional study with biobanked blood samples from 327 postmenopausal women with no evidence of clinical disease. Genotyping for rs1205 C > T SNP of the CRP gene was done by real-time polymerase chain reaction with allelic discrimination assays.

Results

Mean age was 55.6 ± 5.6 years. Mean body mass index (BMI) was 27.3 ± 4.7. Participants were divided according to hs-CRP levels: ≥3 mg/l (low-grade chronic inflammation) or < 3 mg/l. The frequency of allele C at rs1205 was 74.2% in the hs-CRP ≥ 3 mg/l group vs. 59% in the hs-CRP < 3 mg/l. In a multivariable model, higher prevalence of hs-CRP ≥ 3 mg/l was associated with CC genotype (PR 1.53; 95%CI 1.07-2.18; p = 0.018) and waist circumference ≥ 88 cm (PR 2.45; 95%CI 1.66-3.60; p < 0.001).

Conclusions

CRP rs1205 CC homozygotes may be at higher risk of a low-grade chronic inflammatory status compared to individuals carrying the T allele.

Association of high-sensitivity C-reactive protein with susceptibility to Schizophrenia in Tunisian population

The pathogenic mechanisms underlying Schizophrenia (SZ), one of the most frequent mental disorders, are complex and poorly understood. Several evidences suggest that inflammatory processes may underpin some of its neurobiological correlates. The aim of this study was: (i) to analyze the potential association between circulating levels of the C-reactive protein (CRP), a crucial inflammatory marker, and Schizophrenia in Tunisian patients and healthy controls (HC) cohorts; (ii) to investigate the genetic diversity of three CRP variants (rs1417938, rs1130864 and rs1205) and; (iii) to analyze a potential relationship between expression and genetic data and clinical and socio demographical characteristics. CRP polymorphisms were exanimated for 155 patients and 203 HC by taqMan5'-nuclease. High-sensitivity CRP (hs-CRP) serum level was measured in 128 clinically stable out-patient SZ patients and 63 HC subjects via an automated biochemical analyzer. We found that hs-CRP levels were significantly higher in SZ patients as compared to HC. No significant differences were found when the proportions of CRP variants were compared in patients and HC. Further analysis according to clinical and socio demographical characteristics revealed a positive association with age and hypertension. Our data on an original Tunisian sample confirm the previous finding in others population groups.

Systemic low-grade inflammation-associated lifestyle, diet, and genetic factors: A population-based cross-sectional study

OBJECTIVES

Systemic low-grade inflammation (SLGI) is an intermediary common condition to the physiopathology of chronic noncommunicable diseases and targeting its determinants could lead to more efficient public health strategies. We aimed to investigate SLGI-independent associations with lifestyle, diet, and genetic factors in a population-based sample of adults using a systemic low-grade inflammation score (SIS).

METHODS

The study sample is composed of 269 participants from the cross-sectional population-based Health Survey of Sao Paulo (2008-2010), ages 20 to 59 y, whose data on socioeconomic variables, lifestyle, health parameters, and blood samples were available. Diet was assessed by two 24-h recalls, and the Brazilian Health Eating Index-Revised (BHEI-R) was scored. From blood samples, 30 single nucleotide polymorphisms on inflammatory genes were genotyped, and plasma eleven inflammatory biomarkers levels that composed the SIS were determined. A multiple, stepwise, linear regression was used to investigate SIS-independent associated factors.

RESULTS

Factors independently associated with SIS were BHEI-R score (partial R² = 5.1; β = -0.13; P = 0.003), body mass index (partial R² = 3.4; β = 0.19; P = 0.001), TLR4 rs5030728 GA + AA genotype (partial R² = 3.1; β = -1.37; P = 0.008), age 50 to 59 y (partial R² = 2.5; β = 1.93; P = 0.029) in comparison with the reference category (20 to 29 y), and commuting physical activity >150 min/wk (partial R² = 2.2; β = -1.29; P = 0.043) after adjustment for current smoking status, medication use, and dietary misreporting.

CONCLUSIONS

Eating a lower quality diet, having a higher body mass index score and age, being GG homozygous for TLR4 rs5030728, and spending <150 min/wk in transportation physical activity are independent determinants of SLGI.

Low-grade inflammation markers in children and adolescents: Influence of anthropometric characteristics and CRP and IL6 polymorphisms

Overweight and obesity are associated with chronic and subclinical inflammation due to an imbalance of inflammatory mediators. However, the association with gene polymorphism has been rarely studied in children. The aim of this study was to determine if serum concentrations of C-reactive protein (CRP) and interleukin-6 (IL-6) are related to the IL6 rs1800795, IL6 rs2069845 and CRP rs1205 polymorphisms (SNPs) according to body mass index (BMI) in a sample of children and adolescents. A cross-sectional study in 470 students between 7 and 17yearsof age of anthropometric characteristics, high sensitivity-CRP (Hs-CRP) and IL-6 levels and three SNPs genotyped. The prevalence ratio of hs-CRP>3mg/L in obese individuals was 4.15 (CI 2.43-7.06; p=0.01), and it was 1.91 (CI 1.03-3.55; p=0.03) in overweight individuals and 1.74 (CI 1.05-2.88 p=0.03) in females. Individuals with waist circumference (WC) and body fat percentage (BF%) alterations showed elevated levels of hs-CRP (p=4.3×10^-5 and p=5.3×10^-6). The combination of any two anthropometric measurement increases CRP levels, especially combinations with obesity body mass index (BMI): BMI+WC and BMI+BF%. Among the overweight/obesity group, T allele carriers of CRP rs1205 showed lower levels of hs-CRP (0.5, IQR=0.3-1.8mg/L) than CC homozygotes (1.5, IQR=0.4-3.4mg/L, p=0.018). Additionally, considering subjects with two or three anthropometric alterations for CRP rs1205: rs1205 T allele carriers had lower levels of hs-CRP (0.7, IQR=0.3-2.7mg/L) than CC homozygotes (1.2, IQR=0.5-3.5mg/L, p=0.02). In conclusion, carriers of the rs1205/T allele with higher BMIs had lower levels of hs-CRP. Schoolchildren who were overweight/obese had higher levels of CRP and IL-6, whereas individuals with WC and BF% alterations had higher levels of CRP.

Combinations of Polymorphic Markers of Chemokine Genes, Their Receptors and Acute Phase Protein Genes As Potential Predictors of Coronary Heart Diseases

Atherosclerosis, the main factor in the development of coronary heart diseases (CHD), is an inflammatory response to endothelial layer damage in the arterial bed. We have analyzed the association between CHD and the polymorphic markers of genes that control the synthesis of proteins involved in the processes of adhesion and chemotaxis of immunocompetent cells: rs1024611 (-2518A>G, CCL2 gene), rs1799864 (V64I, CCR2 gene), rs3732378 (T280M, CX3CR1 gene), rs1136743 (A70V, SAA1 gene), and rs1205 (2042C>T, CRP gene) in 217 patients with CHD and 250 controls. Using the Monte Carlo method and Markov chains (APSampler), we revealed a combination of alleles/genotypes associated with both a reduced and increased risk of CHD. The most significant alleles/genotypes areSAA1*T/T+CRP*C+CX3CR1*G/A (P perm = 0.0056, OR = 0.07 95%CI 0.009-0.55), SAA1*T+CRP*T+CCR2*G/A+CX3CR1*G (P perm = 0.0063, OR = 14.58 95%CI 1.88-113.04), SAA1*T+CCR2*A+CCL2* G/G (P perm = 0.0351, OR = 10.77 95%CI 1.35-85.74).

C-reactive protein gene variants: independent association with late-life depression and circulating protein levels

C-reactive protein (CRP) is a heritable biomarker of systemic inflammation that is commonly elevated in depressed patients. Variants in the CRP gene that influence protein levels could thus be associated with depression but this has seldom been examined, especially in the elderly. Depression was assessed in 990 people aged at least 65 years as part of the ESPRIT study. A clinical level of depression (DEP) was defined as having a score of ⩾16 on The Center for Epidemiologic Studies Depression scale or a diagnosis of current major depression based on the Mini-International Neuropsychiatric Interview and according to Diagnostic and Statistical Manual of Mental Disorders-IV criteria. Five single-nucleotide polymorphisms spanning the CRP gene were genotyped, and circulating levels of high-sensitivity CRP were determined. Multivariable analyses adjusted for socio-demographic characteristics, smoking, ischemic pathologies, cognitive impairment and inflammation-related chronic pathologies. The minor alleles of rs1130864 and rs1417938 were associated with a decreased risk of depression in women at Bonferroni-corrected significance levels (P=0.002). CRP gene variants were associated with serum levels in a gender-specific manner, but only rs1205 was found to be nominally associated with both an increased risk of DEP and lower circulating CRP levels in women. Variants of the CRP gene thus influence circulating CRP levels and appear as independent susceptibility factors for late-life depression.

Genetic variation across C-reactive protein and risk of prostate cancer

BACKGROUND

Inflammation has been hypothesized to play an important etiological role in the initiation or progression of prostate cancer. Circulating levels of the systemic inflammation marker C-reactive protein (CRP) have been associated with increased risk of prostate cancer. We investigated the role of genetic variation in CRP and prostate cancer, under the hypothesis that variants may alter risk of disease.

METHODS

We undertook a case-control study nested within the prospective Physicians' Health Study among 1,286 men with incident prostate cancer and 1,264 controls. Four single-nucleotide polymorphisms (SNPs) were selected to capture the common genetic variation across CRP (r(2)  > 0.8). We used unconditional logistic regression to assess the association between each SNP and risk of prostate cancer. Linear regression models explored associations between each genotype and plasma CRP levels.

RESULTS

None of the CRP SNPs were associated with prostate cancer overall. Individuals with one copy of the minor allele (C) in rs1800947 had an increased risk of high-grade prostate cancer (OR: 1.7; 95% CI: 1.1-2.8), and significantly lower mean CRP levels (P-value <0.001), however, we found no significant association with lethal disease. Mean CRP levels were significantly elevated in men with one or two copies of the minor allele in rs3093075 and rs1417939, but these were unrelated to prostate cancer risk.

CONCLUSION

Our findings suggest that SNPs in the CRP gene are not associated with risk of overall or lethal prostate cancer. Polymorphisms in CRP rs1800947 may be associated with higher grade disease, but our results require replication in other cohorts.

Genetic risk score and adiposity interact to influence triglyceride levels in a cohort of Filipino women

Background/Objectives:

Individually, genetic variants only moderately influence cardiometabolic (CM) traits, such as lipid and inflammatory markers. In this study we generated genetic risk scores from a combination of previously reported variants influencing CM traits, and used these scores to explore how adiposity levels could mediate genetic contributions to CM traits.

Subjects/Methods:

Participants included 1649 women from the 2005 Cebu Longitudinal Health and Nutrition Survey. Three genetic risk scores were constructed for C-reactive protein (CRP), high-density lipoprotein cholesterol (HDL-C) and triglycerides (TGs). We used linear regression models to assess the association between each genetic risk score and its related trait. We also tested for interactions between each score and measures of adiposity.

Results:

Each genetic risk score explained a greater proportion of variance in trait levels than any individual genetic variant. We found an interaction between the TG genetic risk score (2.29–14.34 risk alleles) and waist circumference (WC) (P_interaction=1.66 × 10⁻²). Based on model predictions, for individuals with a higher TG genetic risk score (75th percentile=12), having an elevated WC (⩾80 cm) increased TG levels from 1.32 to 1.71 mmol l⁻¹. However, for individuals with a lower score (25th percentile=7), having an elevated WC did not significantly change TG levels.

Conclusions:

The TG genetic risk score interacted with adiposity to synergistically influence TG levels. For individuals with a genetic predisposition to elevated TG levels, our results suggest that reducing adiposity could possibly prevent further increases in TG levels and thereby lessen the likelihood of adverse health outcomes such as cardiovascular disease.

Long-term obesity and cardiovascular, inflammatory, and metabolic risk in U.S. adults

BACKGROUND

People worldwide are becoming obese at earlier ages, increasing exposure to long-term obesity.

PURPOSE

To examine how BMI at age 25 years predicts later obesity and test the importance of long-term obesity beyond obesity severity for adult cardiovascular, inflammatory, and metabolic risk.

METHODS

Data from adults aged 35-64 years from the 1999-2010 U.S. National Health and Nutrition Examination Survey were analyzed in 2013 to test how BMI at age 25 years predicts later adult BMI. Next, logistic regression models predicted the odds of elevated risk for blood pressure (BP); high-density lipoprotein cholesterol; total cholesterol; triglycerides; C-reactive protein (CRP); and glycosylated hemoglobin (HbA1c) by BMI at age 25 years and current BMI.

RESULTS

Men obese at age 25 years had a 23.1% estimated probability of Class III obesity after age 35 years, compared to a 1.1% probability for men of normal weight at this age. For women, these probabilities were 46.9% and 4.8%, respectively. Those obese in both periods had higher odds of elevated BP, CRP, and HbA1c compared to those of normal weight at age 25 years, with no effects for lipids. After adjustment for current BMI, these associations were either eliminated (for BP and CRP) or greatly reduced (HbA1c).

CONCLUSIONS

The biological risks of long-term obesity are primarily due to the risk of more severe obesity later in life among those obese early in life, rather than obesity duration. Current body weight rather than duration may be the best reflection of clinical cardiovascular and metabolic risk.

Haplotypes in the CRP gene associated with increased BMI and levels of CRP in subjects with type 2 diabetes or obesity from Southwestern Mexico

Objective. We evaluated the association between four polymorphisms in the CRP gene with circulating levels of C-reactive protein (CRP), type 2 diabetes (T2D), obesity, and risk score of coronary heart disease. Methods. We studied 402 individuals and classified them into four groups: healthy, obese, T2D obese, and T2D without obesity, from Guerrero, Southwestern Mexico. Blood levels of CRP, glucose, cholesterol, triglycerides, and leukocytes were measured. Genotyping was performed by PCR/RFLP, and the risk score for coronary heart disease was determined by the Framingham's methodology. Results. The TT genotype of SNP rs1130864 was associated with increased body mass index and T2D patients with obesity. We found that the haplotype 2 (TGAG) was associated with increased levels of CRP (β = 0.3; 95%CI: 0.1, 0.5; P = 0.005) and haplotype 7 (TGGG) with higher body mass index (BMI) (β = 0.2; 95%CI: 0.1, 0.3; P < 0.001). The risk score for coronary heart disease was associated with increased levels of CRP, but not with any polymorphism or haplotype. Conclusions. The association between the TT genotype of SNP rs1130864 with obesity and the haplotype 7 with BMI may explain how obesity and genetic predisposition increase the risk of diseases such as T2D in the population of Southwestern Mexico.

Association study of candidate gene polymorphisms and obesity in a young Mexican-American population from South Texas

BACKGROUND AND AIMS

Obesity is increasingly a health problem and a risk factor for diabetes in young Mexican-American populations. Genetic association studies in older, mostly non-Hispanic populations have reported that polymorphisms in the candidate genes HSD11B1, CRP, ADIPOQ, PPARG, ANKK1, ABCC8 and SERPINF1 are associated with obesity or diabetes. We analyzed the polymorphisms rs846910, rs1205, rs1501299, rs1801282, rs1800497, rs757110 and rs1136287 in these candidate genes, for association with obesity and metabolic traits in a young Mexican-American population from south Texas.

METHODS

Genotyping of the seven common SNPs were performed by allelic discrimination assays in 448 unrelated Mexican Americans (median age = 16 years) from south Texas. χ(2) tests and regression analyses using additive models were used for genetic association analyses adjusting for covariates; p values were corrected for multiple testing by permutation analyses.

RESULTS

rs1800497 (ANKK1) shows association with waist circumference (p = 0.009) and retains the association (p = 0.03) after permutation testing. Analysis of metabolic quantitative traits shows that rs846910 (HSD11B1) was associated with HOMA-IR (p = 0.04) and triglycerides (p = 0.03), and rs1205 (CRP) with HOMA-IR (p = 0.03) and fasting glucose levels (p = 0.007). However, the quantitative traits associations are not maintained after permutation analysis. None of the other SNPs in this study showed associations with obesity or metabolic traits in this young Mexican-American population.

CONCLUSIONS

We report a potential association between rs1800497 (linked to changes in brain dopamine receptor levels) and central obesity in a young Mexican-American population.

C-reactive protein haplotypes and dispositional optimism in obese and nonobese elderly subjects

Background

Chronic low-grade inflammation, characterized by elevated plasma levels of C-reactive protein (CRP), has been inversely associated with dispositional optimism. Using a Mendelian randomization design, this study explores whether CRP haplotypes that determine CRP plasma levels are also associated with dispositional optimism.

Methods

In a sample of 1,084 community-dwelling subjects (aged 60–85 years) from three cohort studies (Arnhem Elderly Study, n = 426; Leiden Longevity Study, n = 355; Zutphen Elderly Study, n = 303), six CRP polymorphisms (rs2808628, rs2808630, rs1205, rs1800947, rs1417938, and rs3091244) coding for five common haplotypes were genotyped. The association of CRP haplotypes with CRP plasma levels and dispositional optimism was analyzed using multivariable linear regression models. Subanalyses were stratified by body mass index (BMI ≥25 kg/m²).

Results

CRP haplotypes determined CRP plasma levels (adjusted β = 0.094, p < 0.001). In the whole group, no association was found between CRP haplotypes and dispositional optimism scores (adjusted β = −0.02, p = 0.45). In BMI strata, CRP haplotypes were associated with increasing levels of plasma CRP levels (adjusted β = 0.112; p = 0.002) and lower dispositional optimism levels (adjusted β = −0.068; p = 0.03) in the obese group only.

Conclusions

These results suggest that genetically increased CRP levels are involved in low dispositional optimism, but only in case of obesity.

Single-nucleotide polymorphisms at five loci are associated with C-reactive protein levels in a cohort of Filipino young adults

C-reactive protein (CRP) is a component of nonspecific immune defense and is a reliable marker of low-grade inflammation involved in obesity, type 2 diabetes and cardiovascular disease. Genome-wide association studies in middle-aged and elderly populations, predominantly of European descent, demonstrated associations of CRP levels with single-nucleotide polymorphisms (SNPs) at several loci. To examine whether the variants identified are replicated in Filipino young adults, we applied Tobit regression models to study the association of plasma CRP with 12 SNPs at seven loci in a cohort of 1691 Filipino young adults (aged 21.5±0.3 years) from the Cebu Longitudinal Health and Nutrition Survey. SNPs in or near CRP (P=3.2 × 10(-11)), HNF1A, IL6R, APOE-APOC1 and LEPR showed significant associations (P<0.05) and together explained 4.8% of the total variation in CRP. Modest interactions were observed between LEPR-rs1892534 and waist circumference (uncorrected P(interaction)=0.020) and between APOE-rs769449 and pathogen exposure (uncorrected P(interaction)=0.0073) in models predicting CRP. Our results demonstrated that variants in several loci are significantly associated with plasma CRP in Filipino young adults, suggesting shared genetic influences on circulating CRP across populations and age groups.

Genetic variation in C-reactive protein in relation to colon and rectal cancer risk and survival

C-reactive protein (CRP), a biomarker of inflammation, has been shown to be influenced by genetic variation in the CRP gene. In this study, we test the hypothesis that genetic variation in CRP influences both the risk of developing colon and rectal cancer and survival. Two population-based studies of colon cancer (n = 1,574 cases, 1,970 controls) and rectal (n = 791 cases, 999 controls) were conducted. We evaluated four CRP tagSNPs: rs1205 (G > A, 3' UTR); rs1417938 (T > A, intron); rs1800947 (G > C, L184L); and rs3093075 (C > A, 3' flanking). The CRP rs1205 AA genotype was associated with an increased risk of colon cancer (OR 1.3, 95%CI 1.1-1.7), whereas the rs3093075 A allele was associated with a reduced risk of rectal cancer (OR 0.7, 95%CI 0.5-0.9). The strongest association for the rs1205 polymorphism and colon cancer was observed among those with KRAS2 mutations (OR 1.5, 95%CI 1.1-2.0). The CRP rs1205 AA genotype also was associated with an increased risk of CIMP+ rectal tumors (OR 2.5, 95%CI 1.2-5.3); conversely, the rs1417938 A allele was associated with a reduced risk of CIMP+ rectal tumors (OR 0.5, 95%CI 0.3-0.9). We observed interactions between CRP rs1800947 and BMI and family history of CRC in modifying risk of both colon and rectal cancer. These data suggest that genetic variation in the CRP gene influences risk of both colon and rectal cancer development.

Association between adolescent emotional problems and metabolic syndrome: the modifying effect of C-reactive protein gene (CRP) polymorphisms

Depression is associated with the development of the metabolic syndrome, and both depression and metabolic syndrome are associated with markers of systemic inflammation, such as C-reactive protein (CRP). We examined associations between affective status in adolescence and adulthood, and the metabolic syndrome at age 53 years in a large representative British birth cohort. We also investigated whether two CRP gene polymorphisms (rs1205 and rs3093068) were associated with affective status and the metabolic syndrome, and whether the association between affective status and the metabolic syndrome was modified by these CRP polymorphisms. Women, but not men, with emotional problems in adolescence were more likely to have the metabolic syndrome (OR=1.53, 95% CI: 1.04, 2.26), although this sex difference was not statistically significant (p=0.22). The CRP SNPs were not associated with affective status or the metabolic syndrome, but the association of adolescent emotional problems with the metabolic syndrome was stronger in those who were homozygous for the major allele (C) of rs1205 (OR=1.83, 95% CI: 1.17, 2.86) than in carriers of the T allele (OR=1.01, 95% CI: 0.66, 1.55) (p=0.05 for gene by affective status interaction). This interaction was stronger when considering adolescent emotional problems as a continuous variable (p=0.003). Adolescent emotional problems play an important role in the development of the metabolic syndrome later in life, particularly in those homozygous for the major allele of CRP rs1205. These findings may highlight new ways of identifying people with emotional problems at high risk of developing the metabolic syndrome, which is of great importance for the management of the physical health of these patients.

Meta-analysis of genome-wide association studies in >80 000 subjects identifies multiple loci for C-reactive protein levels

BACKGROUND

C-reactive protein (CRP) is a heritable marker of chronic inflammation that is strongly associated with cardiovascular disease. We sought to identify genetic variants that are associated with CRP levels.

METHODS AND RESULTS

We performed a genome-wide association analysis of CRP in 66 185 participants from 15 population-based studies. We sought replication for the genome-wide significant and suggestive loci in a replication panel comprising 16 540 individuals from 10 independent studies. We found 18 genome-wide significant loci, and we provided evidence of replication for 8 of them. Our results confirm 7 previously known loci and introduce 11 novel loci that are implicated in pathways related to the metabolic syndrome (APOC1, HNF1A, LEPR, GCKR, HNF4A, and PTPN2) or the immune system (CRP, IL6R, NLRP3, IL1F10, and IRF1) or that reside in regions previously not known to play a role in chronic inflammation (PPP1R3B, SALL1, PABPC4, ASCL1, RORA, and BCL7B). We found a significant interaction of body mass index with LEPR (P<2.9×10(-6)). A weighted genetic risk score that was developed to summarize the effect of risk alleles was strongly associated with CRP levels and explained ≈5% of the trait variance; however, there was no evidence for these genetic variants explaining the association of CRP with coronary heart disease.

CONCLUSIONS

We identified 18 loci that were associated with CRP levels. Our study highlights immune response and metabolic regulatory pathways involved in the regulation of chronic inflammation.

Association of C-reactive protein gene polymorphisms and colorectal cancer

BACKGROUND

An elevated plasma level of C-reactive protein (CRP) is a risk for, and prognostic factor of, colorectal cancer (CRC). In other reports of CRP concerning cardiovascular disease, CRP level correlated with its gene polymorphisms. We hypothesized that CRP polymorphisms associate risk and prognosis of CRC.

METHODS

This study enrolled 421 patients with CRC and 218 healthy control subjects. After preliminary studies, we selected four single nucleotide polymorphisms (SNPs) in the CRP gene: +2147A > G (rs1205), +942G > C (rs1800947), -717A > G (rs2794521), and -757T > C (rs3093059). At first, analyzing distributions of four SNPs between CRC case and non-CRC control groups was performed. Subsequently, the impacts of these SNPs with other prognostic factors of disease-free interval (DFI) and cancer-specific survival (CSS) were analyzed using uni- and multivariate Cox regression analyses.

RESULTS

The case and control groups differed in the frequency of -757T > C (P = 0.002). The CRC case group had a higher percentage of the TT genotype (odds, 1.75). Regarding prognoses, multivariate analyses revealed that four factors, including stage (I, II, III), gross tumor type (polypoid, ulcerative, infiltrative), location (right, left, rectum), and -757T > C SNP (odds, 1.29; P = 0.048), correlated with DFI; two factors, including stage and +2147A > G SNP (odds, 0.71; P = 0.03), correlated with CSS.

CONCLUSIONS

The -757T > C SNP is a risk for and prognostic factor of DFI; the +2147A > G SNP is a prognostic factor of CSS. CRP polymorphisms associate the risk and survival of CRC.

Inflammatory gene variants in the Tsimane, an indigenous Bolivian population with a high infectious load

The Tsimane of lowland Bolivia are an indigenous forager-farmer population living under conditions resembling pre-industrial European populations, with high infectious morbidity, high infection and inflammation, and shortened life expectancy. Analysis of 917 persons ages 5 to 60+ showed that allele frequencies of 9 SNPs examined in the apolipoprotein E (apoE), C-reactive protein (CRP), and interleukin-6 (IL-6) genes differed from some European, African, and north Asian-derived populations. The apoE2 allele was absent, whereas four SNPs related to CRP and IL-6 were monomorphic: CRP (rs1800947, rs3093061, and rs3093062) and IL-6 (rs1800795). No significant differences in apoE, CRP, and IL-6 variants across age were found CRP levels were higher in carriers of two CRP proinflammatory SNPs, whereas they were lower in carriers of apoE4. Taken together the evidence for (1) different allele frequencies between the Tsimane and other populations and (2) the correlations of CRP and apoE alleles with blood CRP may suggest that these variants are under selection in response to a high infection environment.

Association between C-reactive protein and adiposity in women

CONTEXT

The link between C-reactive protein (CRP) and adiposity deserves to be further explored, considering the controversial diabetogenic role of CRP.

OBJECTIVE

We explored the potential causal role of CRP on measures of adiposity.

DESIGN

We used a Mendelian randomization approach with the CRP and LEPR genes as instrumental variables in a cross-sectional Caucasian population-based study comprising 2526 men and 2836 women. Adiposity was measured using body mass index (BMI), fat and lean mass estimated by bioelectrical impedance, and waist circumference.

RESULTS

Log-transformed CRP explained by the rs7553007 single-nucleotide polymorphism tagging the CRP gene was significantly associated with BMI [regression coefficient: 1.22 (0.18; 2.25), P = 0.02] and fat mass [2.67 (0.65; 4.68), P = 0.01] but not with lean mass in women, whereas no association was found in men. Log-transformed CRP explained by the rs1805096 LEPR single-nucleotide polymorphism was also positively associated, although not significantly, with BMI or fat mass. The combined CRP-LEPR instrument explained 2.24 and 0.77% of CRP variance in women and men, respectively. Log-transformed CRP explained by this combined instrument was significantly associated with BMI [0.98 (0.32; 1.63), P = 0.004], fat mass [2.07 (0.79; 3.34), P = 0.001], and waist [2.09 (0.39; 3.78), P = 0.01] in women but not men.

CONCLUSION

Our data suggest that CRP is causally and positively related to BMI in women and that this is mainly due to fat mass. Results on the combined CRP-LEPR instrument suggest that leptin may play a role in the causal association between CRP and adiposity in women. Results in men were not significant.

Unfavourable risk factors for type 2 diabetes mellitus are already apparent more than a decade before onset in a population-based study of older persons: from the Age, Gene/Environment Susceptibility-Reykjavik Study (AGES-Reykjavik)

We evaluated midlife risk factors of developing type 2 diabetes mellitus (T2DM) in late life in a population-based study of older persons. A cohort of 2,251 persons, aged 65-96, participated in AGES-Reykjavik in 2002-2004; all attended the Reykjavik Study 26 years earlier, at the mean age of 50. Based on glucometabolic status in 2002-2004 the participants are divided into a normoglycemic control group (n = 1,695), an impaired fasting glucose (IFG) group (n = 313) and T2DM group (n = 243). Change in risk parameters from midlife is evaluated retrospectively in these three groups. Since examined earlier 14.3% of men and 8.2% of women developed T2DM. A family history of diabetes was reported in 39.5% of T2DM compared to 19.3% in both IFG and normoglycemics. The T2DM and IFG groups currently have higher levels of fasting triglycerides, greater body mass index (BMI) and higher systolic blood pressure than normoglycemics and this difference was already apparent in midlife. In late life, two or more metabolic syndrome criteria are present in 60% of the T2DM groups compared to 25% in normoglycemic groups. T2DM with impaired cardiovascular health is more marked in women than men when compared with normoglycemics. Family history and higher levels of BMI, triglycerides and systolic blood pressure in midlife are associated with the development of T2DM in late life, suggesting risk can be evaluated long before onset. A continued rise in risk factors throughout life allows for more aggressive measures in preventing or delaying development of T2DM and its effect on cardiovascular health.