No association between the BDNF Val66Met polymorphism and mood status in a non-clinical community sample of 7389 older adults

Recent research has suggested that brain-derived neurotrophic factor (BDNF) may be implicated in the aetiology of mood-related phenotypes. Here we report an investigation of the association between a BDNF coding variant (Val66Met, rs6265) and mood status in a large non-clinical sample of men and women. We genotyped 7389 adult men and women, aged 41-80 years, selected from participants in the European Prospective Investigation into Cancer and Nutrition in Norfolk (EPIC-Norfolk, United Kingdom). Evidence of past year prevalent, lifetime and recurrent episodic major depressive disorder (MDD) and of past year prevalent and lifetime generalised anxiety disorder (GAD), defined by DSM-IV diagnostic criteria, was assessed through questionnaire together with a five-item version of the Mental Health Inventory (MHI-5). A total of 1214 (16.4%) participants reported lifetime MDD and 355 (4.8%) reported lifetime GAD. In this population based study we found no evidence to support an association between the BDNF gene Val66Met polymorphism and mood status.

Common variants in WFS1 confer risk of type 2 diabetes

We studied genes involved in pancreatic beta cell function and survival, identifying associations between SNPs in WFS1 and diabetes risk in UK populations that we replicated in an Ashkenazi population and in additional UK studies. In a pooled analysis comprising 9,533 cases and 11,389 controls, SNPs in WFS1 were strongly associated with diabetes risk. Rare mutations in WFS1 cause Wolfram syndrome; using a gene-centric approach, we show that variation in WFS1 also predisposes to common type 2 diabetes.

Study of association between common variation in the insulin-like growth factor 2 gene and indices of obesity and body size in middle-aged men and women

CONTEXT

The IGF2 gene (IGF2) plays a key role in growth and is a candidate for association with obesity. Previous studies have reported that polymorphisms in IGF2 are associated with body weight and body mass index (BMI), but the results have been inconsistent.

OBJECTIVES

The aim of this study was primarily to confirm the association with BMI and, secondarily, to study the associations with other indices of body size.

METHODS

In a sample of 2797 women and 2203 men aged 39-79 participating in the Norfolk arm of the European Prospective Investigation of Cancer, we genotyped three single nucleotide polymorphisms (SNPs) in the IGF2 gene that were previously associated with BMI [6815 A/T, 1156 T/C (G/A), and 820 G/A (ApaI)].

RESULTS

No significant associations were observed between these SNPs and BMI. However, all three SNPs were significantly associated with height (P = 0.03 to 0.001). In a backward elimination regression analysis, two SNPs, 1156 T/C (G/A) and 820 G/A, remained independently associated with height (P = 0.003 and P = 0.038, respectively). Haplotype analysis of these two SNPs showed that carriers of the GA haplotype were shorter than carriers of each of the other three haplotypes (P < 0.001 for all comparisons).

CONCLUSIONS

We did not confirm the previously reported associations between IGF2 polymorphisms and BMI. However, our results suggest that common variation in the IGF2 gene may be associated with adult height. IGF2 could be considered as a candidate gene for future research on mechanisms for the association between height and chronic diseases, such as cancer, diabetes, and coronary heart disease.

Elevated serum ferritin levels predict new-onset type 2 diabetes: results from the EPIC-Norfolk prospective study

AIMS/HYPOTHESIS

The aim of this study was to examine the association between baseline body iron stores and new-onset diabetes.

SUBJECTS AND METHODS

We studied the association between baseline serum ferritin concentration and type 2 diabetes in 360 clinically incident diabetes cases and 758 controls nested within the EPIC (European Prospective Investigation of Cancer)-Norfolk Cohort Study. Serum ferritin levels were categorised into five groups: sex-specific quartiles of the normal range of ferritin and a group with clinically raised ferritin below levels indicative of haemochromatosis.

RESULTS

Baseline serum ferritin was higher among cases than control participants (geometric mean: men 96.6 vs 67.8 ng/ml, respectively, p < 0.001; women 45.9 vs 34.8 ng/ml, respectively, p = 0.005). In analyses adjusted for known risk factors (age, BMI, sex, family history, physical activity, smoking habit) and dietary factors measured by 7-day food diary, the risk of diabetes was markedly elevated in participants with clinically raised ferritin compared with the lowest quartile (odds ratio [OR] 7.4, 95% CI 3.5-15.4). Further adjustment for potential confounding by inflammation (C-reactive protein, IL-6 and fibrinogen) had no material impact on the observed association, while adjustment for hepatic enzymes (alanine aminotransferase and gamma glutamyl transferase) and adiponectin attenuated the magnitude of association, but it remained statistically significant (OR 3.2 [1.3-7.6]).

CONCLUSIONS/INTERPRETATION

Serum ferritin is an important and independent predictor of the development of diabetes. This finding may have important implications for understanding the aetiology of diabetes.

Role of the apolipoprotein B-apolipoprotein A-I ratio in cardiovascular risk assessment: a case-control analysis in EPIC-Norfolk

BACKGROUND

An elevated apolipoprotein B-apolipoprotein A-I (apo B-apo A-I) ratio is a risk factor for future coronary artery disease (CAD). It is not known whether this ratio is better than traditional lipid values for risk assessment and prediction and whether it adds predictive value to the Framingham risk score.

OBJECTIVE

To evaluate whether the apo B-apo A-I ratio is associated with future CAD events independent of traditional lipid measurements and the Framingham risk score and to evaluate the ability of this ratio to predict occurrence of future CAD.

DESIGN

Prospective, nested case-control study.

SETTING

Norfolk, United Kingdom.

PARTICIPANTS

Apparently healthy men and women (45 to 79 years of age) in the European Prospective Investigation into Cancer and Nutrition-Norfolk. Cases (n = 869) were persons who developed fatal or nonfatal CAD. Controls (n = 1511) were persons without CAD who were matched for age, sex, and enrollment period.

MEASUREMENTS

Total cholesterol, high-density lipoprotein (HDL) cholesterol, triglyceride, apolipoprotein, and C-reactive protein levels were measured directly. Low-density lipoprotein (LDL) cholesterol values were calculated by using the Friedewald formula.

RESULTS

The apo B-apo A-I ratio was associated with future CAD events, independent of traditional lipid values (adjusted odds ratio, 1.85 [95% CI, 1.15 to 2.98]), including the total cholesterol-HDL cholesterol ratio, and independent of the Framingham risk score (adjusted odds ratio, 1.77 [CI, 1.31 to 2.39]). However, it did no better than lipid values at discriminating between CAD cases and controls (area under the receiver-operating characteristic curve, 0.670 for total cholesterol-HDL cholesterol ratio vs. 0.673 for apo B-apo A-I ratio [P = 0.38]) and added little to the predictive value of the Framingham risk score (area under the receiver-operating characteristic curve, 0.594 for Framingham risk score alone vs. 0.613 for Framingham risk score plus apo B-apo A-I ratio [P < 0.001]). In addition, it incorrectly classified 41.1% of cases and 50.4% of controls.

LIMITATIONS

No participant was taking lipid-lowering medication, and diabetes was uncommon.

CONCLUSIONS

The apo B-apo A-I ratio is independently associated with, but adds little to, existing measures for CAD risk assessment and discrimination in the general population. Other characteristics of the test, such as the ability to perform it on nonfasting samples, may still make it useful in some settings.

Association between the T-381C polymorphism of the brain natriuretic peptide gene and risk of type 2 diabetes in human populations

Brain natriuretic peptide (BNP/NPPB) is a member of the natriuretic family involved in the regulation of blood pressure and blood volume as well as lipolysis control in human fat cells. Thus BNP may play a role in energy metabolism and metabolic diseases. We therefore assessed the association between the BNP promoter T-381C polymorphism and risk of type 2 diabetes and metabolic and BNP expression traits in several population samples. In French population-based samples (n = 3216), we found that individuals bearing the -381CC genotype had lower (P = 0.005) fasting glucose levels than -381TC or -381TT individuals. Moreover, the -381CC genotype was less frequent in individuals with type 2 diabetes (n = 280, 13.6%) or with impaired fasting glucose (n = 248, 12.9%) compared with normoglycaemic individuals (n = 2485, 17.8%). The adjusted odds ratio (OR) (95% CI) of type 2 diabetes for -381CC individuals was 0.69 (0.47-1.00), P = 0.05, when compared with -381T allele bearers. We replicated this association in four additional case-control studies for type 2 diabetes. The overall OR (95% CI) of type 2 diabetes was 0.85 (0.76-0.96), P = 0.008, (under a recessive model) (3593 cases and 6646 controls in total). We also found that the -381C allele was associated with higher plasma BNP concentrations (P = 0.015, n = 634) and higher BNP promoter activity in reporter gene assays. Collectively, these data suggest that relatively high BNP expression may protect against type 2 diabetes in humans.

The V103I polymorphism of the MC4R gene and obesity: population based studies and meta-analysis of 29 563 individuals

BACKGROUND

Previous studies have suggested that a variant in the melanocortin-4 receptor (MC4R) gene is important in protecting against common obesity. Larger studies are needed, however, to confirm this relation.

METHODS

We assessed the association between the V103I polymorphism in the MC4R gene and obesity in three UK population based cohort studies, totalling 8304 individuals. We also did a meta-analysis of relevant studies, involving 10 975 cases and 18 588 controls, to place our findings in context.

FINDING

In an analysis of all studies, individuals carrying the isoleucine allele had an 18% (95% confidence interval 4-30%, P=0.015) lower risk of obesity compared with non-carriers. There was no heterogeneity among studies and no apparent publication bias.

INTERPRETATION

This study confirms that the V103I polymorphism protects against human obesity at a population level. As such it provides proof of principle that specific gene variants may, at least in part, explain susceptibility and resistance to common forms of human obesity. A better understanding of the mechanisms underlying this association will help determine whether changes in MC4R activity have therapeutic potential.

Physical activity, C-reactive protein levels and the risk of future coronary artery disease in apparently healthy men and women: the EPIC-Norfolk prospective population study

BACKGROUND

Physical activity is inversely associated with the risk of future coronary artery disease. Whether this relationship is in part mediated by lower levels of systemic inflammation, as indicated by C-reactive protein concentrations, is unknown.

METHODS

We performed a nested case-control study among apparently healthy men and women enrolled in the European Prospective Investigation into Cancer and Nutrition-Norfolk prospective population study, to investigate the relationship among habitual (work-related and leisure time) physical activity, cardiovascular risk factors and the risk of future coronary artery disease.

RESULTS

Among men, those with an active lifestyle had a significantly lower risk of future coronary artery disease than those with an inactive lifestyle [odds ratio (OR) 0.65; 95% confidence interval (CI) 0.47-0.90; P for linearity, 0.008], after adjustment for smoking, systolic blood pressure, diabetes, body mass index and low-density lipoprotein and high-density lipoprotein cholesterol. Additional adjustment for C-reactive protein levels attenuated this relationship only slightly (OR 0.68; 95%CI 0.49-0.93; P for linearity, 0.02). Similarly, active women had an adjusted odds ratio of 0.48 (0.28-0.82; P for linearity <0.001) for future coronary artery disease compared with inactive women. Additional adjustment for C-reactive protein levels attenuated this relationship slightly (OR 0.51; 0.30-0.87; P for linearity, 0.003).

CONCLUSIONS

We observed that people with an active lifestyle had a substantially lower risk of future coronary artery disease than people with an inactive lifestyle, and that this relationship was partly mediated through lower levels of established cardiovascular risk factors and in addition, C-reactive protein. This observation suggests that reduced systemic inflammation may be one of the mechanisms through which physical activity leads to reduced cardiovascular risk.

PARL Leu262Val is not associated with fasting insulin levels in UK populations

AIMS/HYPOTHESIS

PARL, the gene encoding presenilins-associated rhomboid-like protein, maps to chromosome 3q27 within a quantitative trait locus that influences components of the metabolic syndrome. Recently, an amino acid substitution (Leu262Val, rs3732581) in PARL was associated with fasting plasma insulin levels in a US white population (N=1031). This variant was also found to modify the positive association between age and fasting insulin. The aim of this study was to test whether these findings could be replicated in two UK population-based cohorts.

METHODS

Participants from the Medical Research Council Ely and Hertfordshire cohort studies were genotyped for this variant using a SNaPshot primer extension assay and Taqman assay respectively. Full phenotypic and genotypic data were available for 3,666 study participants.

RESULTS

Based on a dominant model, we found no association between the Leu262Val polymorphism and fasting insulin levels (p=0.79) or BMI (p=0.98). We did not observe the previously reported interaction between age and genotype on fasting insulin (p=0.14).

CONCLUSIONS/INTERPRETATION

Despite having greater statistical power, our data do not support the previously reported association between PARL Leu262Val and fasting plasma insulin levels, a measure of insulin resistance. Our findings indicate that this variant is unlikely to be an important contributor to insulin resistance in UK populations.

Fibrinogen plasma levels modify the association between the factor XIII Val34Leu variant and risk of coronary artery disease: the EPIC-Norfolk prospective population study

BACKGROUND

The factor (F) XIII Val34Leu variant has been implicated in coronary artery disease (CAD). In vitro evidence suggests an interaction between this variant and fibrinogen concentrations in determining thrombus structure.

OBJECTIVES

To test whether this interaction is relevant in influencing coronary risk in apparently healthy individuals.

METHODS

In an 8-year prospective population study of 25 663 men and women, we compared 898 apparently healthy men and women developing incident CAD with 1580 matched controls.

RESULTS

Overall, the FXIII Val34Leu variant was not associated with the risk of future CAD. However, a significant interaction existed between the Val34Leu variant and fibrinogen levels for the risk of future CAD (P = 0.004). Among people in the lowest tertile of fibrinogen concentrations, LeuLeu carriers had an odds ratio (OR) of 2.88 (95% confidence interval; CI 1.24-6.74) compared to wild-type individuals (P for linearity = 0.003). By contrast, among those in the highest fibrinogen tertile, LeuLeu carriers were had a lower risk than wild-type individuals (OR 0.47, 95% CI 0.18-1.17, P for linearity = 0.1).

CONCLUSIONS

Our results suggest that a significant gene-covariate interaction exists between the FXIII Val34Leu variant and fibrinogen levels. Relationships between genotype and disease risk may be altered by biological covariates. Simplistic paradigms of gene or biomarker associations are unlikely to fully characterize disease risk in populations.

Primary Ewing′s sarcoma of occipital bone

Ewing′s sarcoma commonly involves the long bones. Primary Ewing′s sarcoma of the cranium is rare and is difficult to distinguish from other tumors involving the cranium. Radiological features and immuno-histochemistry are helpful in diagnosing this tumor. In this report we present a rare case of primary Ewing′s sarcoma of the occipital bone and discuss the differential diagnostic options.

Apolipoprotein A-V, triglycerides and risk of coronary artery disease: the prospective Epic-Norfolk Population Study

In mouse models, apolipoprotein A-V (apoA-V) exhibits triglyceride (TG)-lowering effects. We investigated the apoA-V/TG relationship and the association of apoA-V with coronary artery disease (CAD) risk by determining serum apoA-V levels and genotypes in a nested case-control (n = 1,034/2,031) study. Both univariate and multivariate apoA-V levels showed no association with future CAD (P = 0.4 and 0.5, respectively). Unexpectedly, there was a significant positive correlation between serum apoA-V and TG in men and women (r = 0.36 and 0.28, respectively, P < 0.001 each) but a negative correlation between apoA-V and LPL mass (r = -0.14 and -0.12 for men and women respectively, P < 0.001 each). The frequency of the c.56C>G polymorphism did not differ between cases and controls despite significant positive association of c.56G with both apoA-V and TG levels. For -1131T>C, the minor allele was significantly associated with lower apoA-V yet higher TG levels and was overrepresented in cases (P = 0.047). The association of -1131T>C with CAD risk, however, was independent of apoA-V levels and likely acts through linkage disequilibrium with APOC3 variants. The positive correlation of apoA-V levels with TG levels, negative correlation with LPL levels, and lack of association with CAD risk highlight the need for further human studies to clarify the role of apoA-V.

A new sensitive and specific enzyme-linked immunosorbent assay for IgD

We have developed a new highly specific ELISA for IgD, and then used it to measure levels of circulating IgD in the serum of 480 un-selected patients from the East Anglia region of UK. The assay is both extremely sensitive and specific, with a minimum detected IgD concentration of 30 pg/ml and more than 10,000-fold specificity for IgD over all other human immunoglobulins. The assay shows linear dilution characteristics with both purified IgD and human serum, and spiking of purified IgD into either purified immunoglobulins or human serum shows c. 100% recovery. Furthermore, intra-assay and inter-assay coefficients of variation for repeated measurements of the same samples are below 10% and 15% respectively. Measurement of IgD levels on the un-selected patient population showed levels to range from <300 pg/ml to over 100 microg/ml, with a geometric mean of 8 microg/ml. The distribution is approximately normal after log transformation. Levels of circulating IgD were higher in men than in women. There was a significant negative correlation between levels of IgD and age in women, but not in men. Moreover, after adjustment for age and sex, there were statistically significantly higher levels of circulating IgD in male (but not female) smokers, compared to their non-smoking counterparts. These results highlight the care that needs to be taken to control for age, sex and cigarette smoking when examining levels of circulating IgD in future studies.

Meta-analysis of the Gly482Ser variant in PPARGC1A in type 2 diabetes and related phenotypes

AIMS/HYPOTHESIS

Peroxisome proliferator-activated receptor-gamma co-activator-1alpha (PPARGC1A) is a transcriptional co-activator with a central role in energy expenditure and glucose metabolism. Several studies have suggested that the common PPARGC1A polymorphism Gly482Ser may be associated with risk of type 2 diabetes, with conflicting results. To clarify the role of Gly482Ser in type 2 diabetes and related human metabolic phenotypes we genotyped this polymorphism in a case-control study and performed a meta-analysis of relevant published data.

MATERIALS AND METHODS

Gly482Ser was genotyped in a type 2 diabetes case-control study (N=1,096) using MassArray technology. A literature search revealed publications that examined Gly482Ser for association with type 2 diabetes and related metabolic phenotypes. Meta-analysis of the current study and relevant published data was undertaken.

RESULTS

In the pooled meta-analysis, including data from this study and seven published reports (3,718 cases, 4,818 controls), there was evidence of between-study heterogeneity (p<0.1). In the fixed-effects meta-analysis, the pooled odds ratio for risk of type 2 diabetes per Ser482 allele was 1.07 (95% CI 1.00-1.15, p=0.044). Elimination of one of the studies from the meta-analysis gave a summary odds ratio of 1.11 (95% CI 1.04-1.20, p=0.004), with no between-study heterogeneity (p=0.475). For quantitative metabolic traits in normoglycaemic subjects, we also found significant between-study heterogeneity. However, no significant association was observed between Gly482Ser and BMI, fasting glucose or fasting insulin.

CONCLUSIONS/INTERPRETATION

This meta-analysis of data from the current and published studies supports a modest role for the Gly482Ser PPARGC1A variant in type 2 diabetes risk.

IGF1 and IGFBP3 tagging polymorphisms are associated with circulating levels of IGF1, IGFBP3 and risk of breast cancer

Experimental and observational studies in humans and animals suggest that insulin-like growth factor 1 (IGF1) and its principal binding protein, IGFBP3, may influence breast cancer susceptibility. We have examined the association of nine and four single nucleotide polymorphisms (SNPs) in the IGF1 gene and in the IGFBP3 genes, respectively, with circulating levels of their gene products in a population-based study of 600 middle-aged men and women, and in a breast cancer case-control study, comprised 4647 cases and 4564 controls. All study participants are from the East Anglian region of UK. SNPs were specifically chosen to tag all other known SNPs in each gene. Several SNPs in each gene are associated both with circulating levels of their respective proteins and with risk of breast cancer. In particular, the c allele of IGF1 SNPrs1520220 is associated with increased circulating IGF1 (r2=2.1%, P-trend=0.003) in females and an increased risk of breast cancer: odds ratio (OR) (cc/gg)=1.41; 95% confidence intervals (95% CI) 1.11-1.79, P-trend=0.03. The a allele of IGFBP3 SNP rs2854744 is associated with increased circulating IGFBP3 (r2=9.7%, P<10(-9)) and a decreased risk of breast cancer: OR (aa/cc)=0.87; 95% CI 0.77-0.99, P=0.03. Our data indicate that common variants in the IGF1 and IGFBP3 genes are associated with differences in circulating levels of IGF1 and IGFBP3 and with breast cancer risk. More specifically and consistent with experimental models, our data suggest that higher IGF1 levels may increase the risk of breast cancer but higher IGFBP3 levels may be protective.

C-reactive protein levels and coronary artery disease incidence and mortality in apparently healthy men and women: the EPIC-Norfolk prospective population study 1993-2003

INTRODUCTION

Measurement of C-reactive protein (CRP) levels has been proposed as a useful marker to improve the prediction of future coronary artery disease (CAD) risk, but this notion has been challenged recently.

METHODS AND RESULTS

We performed a prospective case-control study among apparently healthy men and women. The odds ratio (OR) for future CAD incidence was 2.49 (95% CI=2.02-3.08, p for linearity <0.0001) unadjusted, and 1.66 (95% CI=1.31-2.12, p for linearity <0.0001), after adjustment for classical cardiovascular risk factors, for top versus bottom quartile of the CRP distribution. Notably, the risk factor adjusted predictive value was substantially stronger for fatal CAD (OR=2.92, 95% CI=1.83-4.67, p for linearity <0.0001) than for non-fatal CAD (OR=1.25, 95% CI=0.93-1.66, p for linearity=0.06). CRP levels were among the strongest predictors of CAD incidence and mortality. CRP levels remained a statistically significant predictor of future CAD, even after adjustment for the Framingham risk score.

CONCLUSIONS

In this British cohort with risk factor levels representative of a contemporary Western population, CRP concentration was among the strongest predictors of CAD incidence and mortality. We suggest that current guidelines on CRP measurement in clinical practice should be based on contemporary and representative populations.

INS VNTR class genotype and indexes of body size and obesity: population-based studies of 7,999 middle-aged men and women

The relevance of the insulin gene (INS) variable number tandem repeat (VNTR) polymorphism to indexes of body size and adult obesity is inconclusive. Given the equivocal reports on the association between the VNTR class genotype at the insulin gene locus and indexes of body size and obesity, we assessed these associations in a series of cohort studies based on 7,999 middle-aged men and women. We found no convincing evidence that INS VNTR class genotype was associated with indexes of body size and adult obesity. These data suggest that INS VNTR class is not an important determinant of size and body weight regulation in middle-aged men and women.

Serum Levels of Type II Secretory Phospholipase A2 and the Risk of Future Coronary Artery Disease in Apparently Healthy Men and Women

OBJECTIVES

To study the prospective relationship between serum levels of type II secretory phospholipase A2 (sPLA2) and the risk of future coronary artery disease (CAD) in apparently healthy men and women.

METHODS AND RESULTS

We conducted a prospective nested case-control study among apparently healthy men and women aged 45 to 79 years. Cases (n=1105) were people in whom fatal or nonfatal CAD developed during follow-up. Controls (n=2209) were matched by age, sex, and enrollment time. sPLA2 levels were significantly higher in cases than controls (9.5 ng/mL; interquartile range [IQR], 6.4 to 14.8 versus 8.3 ng/mL; IQR, 5.8 to 12.6; P<0.0001). sPLA2 plasma levels significantly correlated with age, body mass index, systolic blood pressure, high-density lipoprotein (HDL) cholesterol levels, and C-reactive protein (CRP) levels. Taking into account matching for sex and age and adjusting for body mass index, smoking, diabetes, systolic blood pressure, low-density lipoprotein cholesterol, HDL cholesterol, and CRP levels, the risk of future CAD was 1.34 (1.02 to 1.71; P=0.02) for people in the highest sPLA2 quartile, compared with those in the lowest (P for linearity=0.03).

CONCLUSIONS

Elevated levels of sPLA2 were associated with an increased risk of future CAD in apparently healthy individuals. The magnitude of the association was similar to that observed between CRP and CAD risk, and both associations were independent.

Insulin-like growth factor-I and risk of type 2 diabetes and coronary heart disease: molecular epidemiology

Insulin-like growth factors (IGFs) play a fundamental role in somatic growth and cellular differentiation, metabolism and survival. Indeed, the processes linking nutrition, metabolism and growth are thought to involve a complex interrelation among insulin, growth hormone (GH), IGFs and their binding proteins (IGFBPs). However, accumulating data from both experimental and molecular epidemiological studies indicate that these growth factors may also be important in the pathophysiological processes underlying chronic disease, including type 2 diabetes mellitus, coronary heart disease and cancer. Experimental and observational studies suggest that higher levels of circulating IGF-I may increase risk of several cancers. By contrast, recent prospective epidemiological studies suggest that relatively higher IGF-I levels may reduce the risk of type 2 diabetes and coronary heart disease. However, these relatively small-scale observational studies are susceptible to chance, reverse causality and residual or unmeasured confounding. A 'Mendelian randomization' approach based on large-scale gene association and prospective observational studies might help determine the possible causal role of IGF-I and its binding proteins in the aetiology of type 2 diabetes, coronary heart disease and cancer.

The impact of abnormalities in IGF and inflammatory systems on the metabolic syndrome

OBJECTIVE

Low plasma levels of IGF-I, particularly when coupled with low levels of the potentially inhibitory IGF binding protein (IGFBP)-1 and higher levels of C-reactive protein (CRP), have been implicated in the pathogenesis of metabolic syndrome X and cardiovascular disease. We report the relative contributions of IGFBP-1 and CRP to the occurrence of the metabolic syndrome in a healthy population cohort to establish the extent to which these factors may contribute to subsequent risk of cardiovascular disease.

RESEARCH DESIGN AND METHODS

The volunteers in the study were all participants in the Ely study, a continuing population-based cohort in Ely, Cambridgeshire, U.K. Of 839 individuals studied, 154 (18.4%) fulfilled criteria for the metabolic syndrome.

RESULTS

Subjects with the metabolic syndrome had lower IGFBP-1 (14.4 microg/l [95% CI 12.9-16.0] vs. 25.4 [24.1-26.7], P < 0.001) and higher CRP (1.9 mg/l [1.6-2.2] vs. 1.0 [0.9-1.1], P < 0.001). Logistic regression, adjusted for age, sex, fasting insulin, and IGF-I, demonstrated a striking 14-fold increased risk for the metabolic syndrome (odds ratio 14.1 [4.1-48.4], P < 0.001) in individuals with a CRP value in the highest tertile and IGFBP-1 levels below the median.

CONCLUSIONS

The combination of a high CRP concentration coupled with a low IGFBP-1 results in a dramatic increase in an individual's risk of having the metabolic syndrome. Further elucidation of the biological processes linking the IGF and inflammatory systems may allow the identification of novel therapeutic targets for cardiovascular risk reduction.

Serum insulin-like growth factor-I levels and potential risk of type 2 diabetes

The effects of circulating insulin-like growth factor (IGF)-I on increasing insulin sensitivity are well recognized. IGF-I may have a further important role in maintaining beta-cell mass, and lower IGF-I activity could explain links between small size at birth and risk of type 2 diabetes in short, obese adults. In the representative Avon Longitudinal Study of Pregnancy and Childhood birth cohort, whereas insulin sensitivity is related to early postnatal weight gain, insulin secretion is related to IGF-I level and statural growth. Adult studies suggest that lower IGF-I levels at baseline predict increased risk for developing impaired glucose tolerance and type 2 diabetes. A common genetic polymorphism in the IGF1 gene could influence size at birth, postnatal growth and type 2 diabetes risk, but results of studies have been inconsistent. Extrapolation of these data to short children born small for gestational age is complex. Some have evidence of IGF-I and insulin resistance, suggesting inherent defects in IGF-I signalling. These children have poor growth responses to growth hormone (GH) therapy and perhaps the highest type 2 diabetes risk. Where these metabolic abnormalities are less severe, responses to GH therapy are good and diabetes risk may then depend on other genetic factors, indicated by a family history of diabetes or origin from ethnic groups with high diabetes prevalence.

Large spontaneous coronary artery dissections-a study of three cases, literature review, and possible therapeutic strategies

Spontaneous coronary artery dissection is rare, but is now being increasingly recognized as a prominent cause of acute ischemic coronary events occurring usually in relatively young patients, predominantly females. The authors describe the clinical course of 3 patients (1 woman) in whom large spontaneous coronary artery dissections developed. All had diverse clinical presentations;1 presenting with heart failure, the second with post-myocardial infarction angina, and the third with syncope. The second patient underwent coronary angioplasty with multiple overlapping stents while in the other two, it was the considered opinion to continue aggressive medical therapy. The 1-year follow-up was uneventful in all 3 patients. The risk factors ascertained in our patients were diabetes mellitus, smoking, and hypertension.

Insulin sensitivity and secretion in normal children related to size at birth, postnatal growth, and plasma insulin-like growth factor-I levels

AIMS/HYPOTHESIS

Type 2 diabetes risk is associated with low birth weight, rapid weight gain during childhood, and shorter stature and lower circulating IGF-I levels in adults. The largest variations in growth rates occur during the first postnatal years. We hypothesised that early postnatal variations in height and weight gain and IGF-I levels may be associated with risk markers for adult disease.

METHODS

We measured the fasting insulin sensitivity (Homeostasis model) and insulin secretion post-oral glucose (insulinogenic index 0-30 min) in 851 normal 8-year-old children from a prospective birth cohort. We examined associations between size at birth, postnatal weight gain and circulating IGF-I levels with insulin sensitivity and secretion at 8 years of age.

RESULTS

Fasting insulin sensitivity at 8 years was closely related to current BMI (r= -0.33, p<0.0005). Lower insulin sensitivity and higher BMI and waist circumference were all predicted by greater weight gain between birth to 3 years of age (all p<0.0005); lower birth weight was associated with reduced insulin sensitivity only in the highest current BMI tertile ( r=0.17, p=0.006). In contrast, lower insulin secretion was related to smaller size at birth ( p=0.01), independent of postnatal weight gain and insulin sensitivity. Lower insulin secretion was also independently related to shorter stature at 8 years of age relative to parental height ( p=0.047) and with lower plasma IGF-I levels at 5 years of age ( n=252, p=0.004).

CONCLUSIONS/INTERPRETATION

Associations between lower birth weight and insulin resistance may be dependent on rapid weight gain during the early postnatal years. However, irrespective of postnatal weight gain, smaller size at birth, lower IGF-I levels and lower childhood height predicted reduced compensatory insulin secretion.