Cohort profile: 1958 British birth cohort (National Child Development Study)

25-hydroxyvitamin D, IGF-1, and metabolic syndrome at 45 years of age: a cross-sectional study in the 1958 British Birth Cohort

OBJECTIVE

Hypovitaminosis D and reduced IGF-1 are associated, individually, with metabolic syndrome. Physiological interactions between vitamin D and IGF-1 are reported; this is the first study to investigate their combined associations with metabolic syndrome prevalence.

RESEARCH DESIGN AND METHODS

Data on 25-hydroxyvitamin D (25(OH)D), IGF-1, and metabolic syndrome abnormalities (abdominal obesity; raised A1C, blood pressure, and triglycerides; and low HDL cholesterol) were collected from 6,810 British white subjects in the 1958 cohort, surveyed during 2002-2004 (age 45 years).

RESULTS

IGF-1 concentrations increased with 25(OH)D up to approximately 75-85 nmol/l but not thereafter. Both 25(OH)D and IGF-1 were inversely associated with metabolic syndrome. There was an interaction between 25(OH)D and IGF-1 (P = 0.025) on metabolic syndrome prevalence: IGF-1 was not significantly associated with metabolic syndrome among those with the lowest levels of 25(OH)D (P > 0.09), whereas higher 25(OH)D was associated with metabolic syndrome at all IGF-1 concentrations (P </= 0.006). Metabolic syndrome prevalence was lowest for participants with the highest concentrations of both 25(OH)D and IGF-1 (odds ratio for highest vs. lowest third of both 0.26 [95% CI 0.17-0.40], P < 0.0001; adjusted for sex, month, hour, inactivity, alcohol consumption, smoking, and social class). 25(OH)D was associated with the prevalence of high A1C, blood pressure, and triglycerides after adjustment for IGF-1, obesity, and social and lifestyle variations (P </= 0.004 for all comparisons).

CONCLUSIONS

Serum 25(OH)D is inversely associated with metabolic syndrome, whereas the inverse association with IGF-1 was found only among those without hypovitaminosis D. These results suggest that metabolic syndrome prevalence is the lowest when both 25(OH)D and IGF-1 are high.

Childhood and adulthood socio-economic position and midlife depressive and anxiety disorders

This paper investigates how childhood socio-economic position influences the risk for midlife depressive and anxiety disorders at 45 years of age, assessed by the Clinical Interview Schedule in 9377 participants of the 1958 British Birth Cohort. Socio-economic position was measured by Registrar General Social Class in childhood and adulthood. The association of paternal manual socio-economic position with any diagnosis at 45 years of age was accounted for after adjustment for adult socio-economic position. Manual socio-economic position in women at 42 years of age was associated with midlife depressive disorder and any diagnosis; these associations were diminished by adjustment for childhood psychological disorders. Effects of childhood socio-economic position on adult depressive disorders may be mediated through adult socio-economic position.

Sex differences in the associations between birthweight and lipid levels in middle-age: findings from the 1958 British birth cohort

OBJECTIVE

To examine sex differences in birthweight-lipid associations.

METHODS AND RESULTS

Using prospectively collected data on birthweight and non-fasting lipid levels at age 44-45 y from the 1958 British birth cohort (3603 men and 3583 women), sex differences in birthweight-lipid associations were examined. There were inverse associations between birthweight and total and low-density-lipoprotein (LDL)-cholesterol among women (a 1 kg increase in birthweight was associated with a 0.13 mmol/L reduction in total cholesterol (p<0.001) and a 0.07 mmol/L reduction in LDL-cholesterol (p=0.02)) but no associations among men (p=0.005 and p=0.01, respectively, for birthweight x sex interactions). There was an inverse association between birthweight and triglycerides of a similar magnitude in both sexes (a 1 kg increase in birthweight was associated with a 7% reduction in triglyceride levels in sex-adjusted models (p<0.001)). There was no association between birthweight and high-density-lipoprotein-cholesterol. Associations were largely unaltered after adjustment for covariates. Of birthweight, current height and BMI, the latter was the strongest predictor of lipid levels.

CONCLUSIONS

The finding of an inverse association between birthweight and triglycerides in both sexes and of inverse associations between birthweight and total and LDL-cholesterol only in women suggests that the mechanisms underlying the associations with birthweight may vary for different lipids.

The candidate genes TAF5L, TCF7, PDCD1, IL6 and ICAM1 cannot be excluded from having effects in type 1 diabetes

BACKGROUND

As genes associated with immune-mediated diseases have an increased prior probability of being associated with other immune-mediated diseases, we tested three such genes, IL23R, IRF5 and CD40, for an association with type 1 diabetes. In addition, we tested seven genes, TAF5L, PDCD1, TCF7, IL12B, IL6, ICAM1 and TBX21, with published marginal or inconsistent evidence of an association with type 1 diabetes.

METHODS

We genotyped reported polymorphisms of the ten genes, nonsynonymous SNPs (nsSNPs) and, for the IL12B and IL6 regions, tag SNPs in up to 7,888 case, 8,858 control and 3,142 parent-child trio samples. In addition, we analysed data from the Wellcome Trust Case Control Consortium genome-wide association study to determine whether there was any further evidence of an association in each gene region.

RESULTS

We found some evidence of associations between type 1 diabetes and TAF5L, PDCD1, TCF7 and IL6 (ORs = 1.05 - 1.13; P = 0.0291 - 4.16 x 10-4). No evidence of an association was obtained for IL12B, IRF5, IL23R, ICAM1, TBX21 and CD40, although there was some evidence of an association (OR = 1.10; P = 0.0257) from the genome-wide association study for the ICAM1 region.

CONCLUSION

We failed to exclude the possibility of some effect in type 1 diabetes for TAF5L, PDCD1, TCF7, IL6 and ICAM1. Additional studies, of these and other candidate genes, employing much larger sample sizes and analysis of additional polymorphisms in each gene and its flanking region will be required to ascertain their contributions to type 1 diabetes susceptibility.

Early life influences on adult leg and trunk length in the 1958 British birth cohort

OBJECTIVES

Short leg length has been associated with increased disease risk. We investigated (1) whether taller childhood stature predicts longer adult leg than trunk length; (2) the effects of early life factors on adult leg/trunk length.

METHODS

We used data from the 1958 British birth cohort on height in childhood and at 45 years, leg and trunk length at 45 years and early life factors (n approximately 5,900).

RESULTS

For a SD increase in height at 7 years, adult leg length increased more than trunk length (2.5-2.8 cm vs. 1.9 cm). Parental height had a stronger association with adult than childhood height, and leg than trunk length. Prenatal factors were associated with leg (maternal smoking) and trunk length (birth order); birth weight had a similar effect on leg and trunk lengths. Large family size, overcrowding, and social housing were more strongly associated with leg than trunk length: deficits in adult height (0.4-0.8 cm) were mostly due to shorter legs.

CONCLUSIONS

Socio-economic adversity in childhood is associated with delayed early growth, shorter adult leg length, and stature. Leg length is the height component most sensitive to early environment. Studies of early life and adult disease could usefully assess adult leg length in addition to height.

Is there an association between hysterectomy and subsequent adiposity?

Objectives

To examine the associations between hysterectomy and subsequent adiposity and to investigate whether these associations vary by characteristics of hysterectomy and are independent of pre-hysterectomy adiposity and potential confounding factors.

Methods

Using information on women from the 1946 and 1958 British birth cohort studies (N = 1790 and 4552, respectively), collected prospectively across life, regression analyses were used to examine the associations between hysterectomy and subsequent body mass index (BMI) and waist circumference.

Results

In unadjusted analyses there was a difference of 1.18 kg/m² (95% CI: 0.64, 1.74) in mean BMI and of 2.72 cm (1.45, 3.99) in waist circumference at age 44–45 years between women who had undergone hysterectomy and those who had not in the 1958 cohort, and differences of 0.76 kg/m² (−0.05, 1.57) and 0.34 cm (−1.58, 2.26) at age 43 years and 0.81 kg/m² (0.14, 1.49) and 1.45 cm (−0.15, 3.05) at age 53 years in the 1946 cohort. These differences attenuated and were no longer significant after adjustment for pre-hysterectomy BMI and confounders. There was no strong evidence of variation in associations by oophorectomy status, timing, route of or reason for procedure.

Conclusions

This study demonstrates that British women who had previously undergone hysterectomy had higher BMI and waist circumference in middle-age than others. These differences appear to be accounted for by the higher BMI in earlier adulthood and increased levels of risk factors associated with both adiposity and hysterectomy risk among women who had undergone hysterectomy. This suggests that women are unlikely to gain weight as a direct result of hysterectomy.

Examining life-course influences on chronic disease: the importance of birth cohort studies from low- and middle- income countries. An overview

The objectives of this overview are to describe the past and potential contributions of birth cohorts to understanding chronic disease aetiology; advance a justification for the maintenance of birth cohorts from low- and middle-income countries (LMIC); provide an audit of birth cohorts from LMIC; and, finally, offer possible future directions for this sphere of research. While the contribution of birth cohorts from affluent societies to understanding disease aetiology has been considerable, we describe several reasons to anticipate why the results from such studies might not be directly applied to LMIC. More than any other developing country, Brazil has a tradition of establishing, maintaining and exploiting birth cohort studies. The clear need for a broader geographical representation may be precipitated by a greater collaboration worldwide in the sharing of ideas, fieldwork experience, and cross-country cohort data comparisons in order to carry out the best science in the most efficient manner. This requires the involvement of a central overseeing body--such as the World Health Organization--that has the respect of all countries and the capacity to develop strategic plans for 'global' life-course epidemiology while addressing such issues as data-sharing. For rapid progress to be made, however, there must be minimal bureaucratic entanglements.

Television viewing and obesity: a prospective study in the 1958 British birth cohort

OBJECTIVE

To assess whether frequency of television viewing in adolescence (11 and 16 years) or early adulthood (23 years) affected subsequent changes in body mass index (BMI) through to mid-adulthood life, and waist-hip ratio in mid-adulthood.

SUBJECTS

The 1958 British birth cohort includes all births in 1 week in March 1958 in England, Scotland and Wales. The main analyses included at least 11 301 participants. Outcome measures included BMI at 16, 23, 33 and 45 years and waist-hip ratio at 45 years.

RESULTS

Watching television 'often' at 16 years (but not 11 years) was associated with a faster gain in BMI between 16 and 45 years in males (0.011 kg m(-2) per year, 95% confidence interval (CI) 0.003, 0.019) and females (0.013 kg m(-2) per year, 95%CI 0.003, 0.023). More frequent television viewing at 11, 16 and 23 years was associated with a faster gain in BMI between 23 and 45 years in females, but not in males. Television viewing at 23 years was associated with waist-hip ratio at 45 years: participants watching > or = 5 times per week had a waist-hip ratio 0.01 higher than those watching less often. At 45 years, those watching television for > or = 4 h day(-1) had a waist-hip ratio 0.03-0.04 higher than those watching for <1 h day(-1).

CONCLUSIONS

More frequent television viewing in adolescence and early adulthood is associated with greater BMI gains through to mid-adulthood and with central adiposity in mid-life. Television viewing may be a useful behaviour to target in strategies to prevent obesity.

Large-scale genetic fine mapping and genotype-phenotype associations implicate polymorphism in the IL2RA region in type 1 diabetes

Genome-wide association studies are now identifying disease-associated chromosome regions. However, even after convincing replication, the localization of the causal variant(s) requires comprehensive resequencing, extensive genotyping and statistical analyses in large sample sets leading to targeted functional studies. Here, we have localized the type 1 diabetes (T1D) association in the interleukin 2 receptor alpha (IL2RA) gene region to two independent groups of SNPs, spanning overlapping regions of 14 and 40 kb, encompassing IL2RA intron 1 and the 5' regions of IL2RA and RBM17 (odds ratio = 2.04, 95% confidence interval = 1.70-2.45; P = 1.92 x 10(-28); control frequency = 0.635). Furthermore, we have associated IL2RA T1D susceptibility genotypes with lower circulating levels of the biomarker, soluble IL-2RA (P = 6.28 x 10(-28)), suggesting that an inherited lower immune responsiveness predisposes to T1D.

Life-time socio-economic position and cortisol patterns in mid-life

The influence of adversity over long periods of the life-span on adult cortisol metabolism is not established. We assess whether morning cortisol levels are associated with socio-economic position (SEP) from birth to mid-adulthood, and if so, whether the association is due primarily to SEP in childhood, adulthood or both. Data are from 6335 participants in the 1958 British birth cohort, with salivary cortisol samples collected at 45 yr. Two saliva samples were obtained on the same day: 45 min post-waking (t1) and 3 h later (t2). Median t1 and t2 cortisol values were 18.80 and 7.10 nmol/l for men; 19.60 and 6.60 nmol/l for women. Three outcomes were constructed: (1) extreme t1 cortisol (top and bottom 5%), (2) area-under-curve (AUC), and (3) abnormal t1-t2 pattern. All three outcomes were associated with lifetime SEP but the relative contribution of childhood and adulthood SEP varied by outcome measure. Our results suggest that the impact of less advantaged SEP over a lifetime would lead to an approximate doubling of the proportion of extreme post-waking cortisol levels for both sexes; an 8% and 10% increase, respectively for females and males in AUC, and an increased risk of having an abnormal cortisol pattern of 60% and 91%. SEP differences were independent of time of waking and sample collection, and in most instances, remained after adjustment for smoking and body mas index (BMI). Thus, our study provides evidence for effects of chronic adversity on cortisol in mid-adult life.

Platelet genomics and the risk of atherothrombosis

Platelets play a pivotal role in atherothrombosis after coronary artery plaque rupture. The extent of response of platelets to such an event varies between individuals. This variation is for a large extent genetically controlled. A comprehensive study of sequence variation that modifies the platelet response to agonists is, however, lacking. We set out to discover the regulatory nodes of platelet function by an integrated systems biology approach. The high density genotyping of 110 genes in a cohort of more than 500 individuals, in whom the platelet response to ADP and collagen-related peptide was determined, allowed the robust definition of the first set of regulatory nodes. Microarray and proteomics studies on platelets from individuals with a so-called 'extreme end' response phenotype provided further insight into key regulators of platelet function. In addition, the completion of the HapMap project allows the comprehensive surveying of the genome for sequence variation by the testing of a limited number of single nucleotide polymorphisms (SNPs). With the advent of high density (i.e. 500,000 SNPs) genotyping arrays large number of case and control samples can be tested at an affordable cost. The recently completed Wellcome Trust Case Control Consortium (WTCCC) study has allowed us to address the question of whether common sequence variation confers risk for seven common diseases, one being myocardial infarction. The results of the WTCCC genome-wide association study and issues of case-control study design, particularly the selection of suitable controls, will be reviewed. In conclusion the integration of the results from the platelet systems biology study with those of the WTCCC project enhances our understanding of the mechanisms underlying common conditions such as atherothrombosis and provides pointers to novel cellular mechanisms and pathways.

Genome-wide association study of 14,000 cases of seven common diseases and 3,000 shared controls

There is increasing evidence that genome-wide association (GWA) studies represent a powerful approach to the identification of genes involved in common human diseases. We describe a joint GWA study (using the Affymetrix GeneChip 500K Mapping Array Set) undertaken in the British population, which has examined approximately 2,000 individuals for each of 7 major diseases and a shared set of approximately 3,000 controls. Case-control comparisons identified 24 independent association signals at P < 5 x 10(-7): 1 in bipolar disorder, 1 in coronary artery disease, 9 in Crohn's disease, 3 in rheumatoid arthritis, 7 in type 1 diabetes and 3 in type 2 diabetes. On the basis of prior findings and replication studies thus-far completed, almost all of these signals reflect genuine susceptibility effects. We observed association at many previously identified loci, and found compelling evidence that some loci confer risk for more than one of the diseases studied. Across all diseases, we identified a large number of further signals (including 58 loci with single-point P values between 10(-5) and 5 x 10(-7)) likely to yield additional susceptibility loci. The importance of appropriately large samples was confirmed by the modest effect sizes observed at most loci identified. This study thus represents a thorough validation of the GWA approach. It has also demonstrated that careful use of a shared control group represents a safe and effective approach to GWA analyses of multiple disease phenotypes; has generated a genome-wide genotype database for future studies of common diseases in the British population; and shown that, provided individuals with non-European ancestry are excluded, the extent of population stratification in the British population is generally modest. Our findings offer new avenues for exploring the pathophysiology of these important disorders. We anticipate that our data, results and software, which will be widely available to other investigators, will provide a powerful resource for human genetics research.

Sequence variants in the genes for the interleukin-23 receptor (IL23R) and its ligand (IL12B) confer protection against psoriasis

Psoriasis is an inflammatory skin disorder that is inherited as a multifactorial trait. Genetic analyses have repeatedly identified a primary disease susceptibility locus lying within the major histocompatibility complex (MHC), on chromosome 6p21. A small number of non-MHC susceptibility loci have also been identified. These regions tend to overlap with susceptibility intervals for Crohn's disease and atopic dermatitis, suggesting the possibility that genetic variants affecting inflammatory pathways may contribute to the pathogenesis of multiple disorders. Here, we report a genetic analysis of the interleukin 23 receptor gene (IL23R), which was recently identified as a susceptibility determinant for Crohn's disease. We initially examined the results of a whole-genome association scan, carried out on 318 cases and 288 controls. We observed a significant increase of a non-synonymous substitution (p.Arg381Gln) among controls (P = 0.00036). We validated this finding by extending our cohort to include a further 519 cases and 528 controls. In the overall sample, the frequency of the 381Gln allele was 3.6% in cases and 7% in controls, yielding a P value of 0.00014. Next, we examined genetic variation at the IL12RB1, IL23A and IL12B genes, respectively, encoding the second subunit of the IL23R receptor and the two subunits of its ligand. This analysis identified independent associations for IL12B SNPs rs10045431 (P value for the extended dataset = 0.0001) and rs3212227 (P = 0.036). Altogether, these findings indicate that genes participating in IL23 signalling play a significant role in the pathogenesis of chronic epithelial inflammation.

Body mass index throughout the life-course and blood pressure in mid-adult life: a birth cohort study

BACKGROUND

The contribution of body mass index (BMI) at different life stages to adult blood pressure (BP) is not well known. We investigated whether changes in BMI across childhood and adulthood, and birthweight, influence BP in mid-adulthood.

METHODS AND RESULTS

In 9297 participants in the 1958 British birth cohort, we analysed BMI measures at several ages (7, 11, 16, 33 and 45 years) and BP at 45 years. Positive BMI/BP associations strengthened with age; at 45 years a standard deviation (SD) increase in concurrent BMI was associated with an increase in systolic blood pressure (SBP) of 3.9 mmHg [95% confidence interval (CI) 3.6-4.2] and an elevated risk of hypertension (odds ratio 1.68; 95% CI 1.60-1.76). The effect of concurrent BMI on BP strengthened with decreasing childhood BMI; among the thinnest 10% at 11 years, SBP increased by 5.5 mmHg per SD increase in concurrent BMI; among the heaviest 10% the increase was 3.3 mmHg. Excessive BMI gain, especially recently, was associated with raised BP; allowing for BMI at 33 years, a SD increase in BMI between 33 and 45 years was associated with an SBP increase of 4.1 mmHg (95% CI 3.6-4.6). Birthweight was inversely associated with BP; SBP reduced by 1.3 mmHg (95% CI 0.9-1.7) per SD increase in birthweight, independently of BMI.

CONCLUSION

High BMI and excessive BMI gain at any life stage, particularly recently, is associated with increased adult BP. Relatively thin children were vulnerable to BMI gain and increased BP in adulthood. Elevated BP associated with low birthweight was not caused by 'catch-up' growth.

Type 2 diabetes TCF7L2 risk genotypes alter birth weight: a study of 24,053 individuals

The role of genes in normal birth-weight variation is poorly understood, and it has been suggested that the genetic component of fetal growth is small. Type 2 diabetes genes may influence birth weight through maternal genotype, by increasing maternal glycemia in pregnancy, or through fetal genotype, by altering fetal insulin secretion. We aimed to assess the role of the recently described type 2 diabetes gene TCF7L2 in birth weight. We genotyped the polymorphism rs7903146 in 15,709 individuals whose birth weight was available from six studies and in 8,344 mothers from three studies. Each fetal copy of the predisposing allele was associated with an 18-g (95% confidence interval [CI] 7-29 g) increase in birth weight (P=.001) and each maternal copy with a 30-g (95% CI 15-45 g) increase in offspring birth weight (P=2.8x10-5). Stratification by fetal genotype suggested that the association was driven by maternal genotype (31-g [95% CI 9-48 g] increase per allele; corrected P=.003). Analysis of diabetes-related traits in 10,314 nondiabetic individuals suggested the most likely mechanism is that the risk allele reduces maternal insulin secretion (disposition index reduced by ~0.15 standard deviation; P=1x10-4), which results in increased maternal glycemia in pregnancy and hence increased offspring birth weight. We combined information with the other common variant known to alter fetal growth, the -30G-->A polymorphism of glucokinase (rs1799884). The 4% of offspring born to mothers carrying three or four risk alleles were 119 g (95% CI 62-172 g) heavier than were the 32% born to mothers with none (for overall trend, P=2x10-7), comparable to the impact of maternal smoking during pregnancy. In conclusion, we have identified the first type 2 diabetes-susceptibility allele to be reproducibly associated with birth weight. Common gene variants can substantially influence normal birth-weight variation.

Asthma onset and relapse in adult life: the British 1958 birth cohort study

BACKGROUND

Few studies have investigated adult-onset wheezing because of difficulties identifying childhood asthma or wheeze retrospectively.

OBJECTIVE

To investigate risk factors for the incidence and recurrence of wheezing illness in adulthood.

METHODS

British children born during 1 week in 1958 (N = 18,558) were followed up periodically. Information on wheezing illness was obtained via parental interviews at ages 7, 11, and 16 years and via cohort member interviews at ages 23, 33, and 42 years. At ages 44 to 45 years a subset (N = 12,069) was targeted for biomedical survey, and total IgE and specific IgE responses to grass, cat, and dust mite were measured.

RESULTS

Incidences of wheezing illness at ages 17 to 33 and 34 to 42 years were positively associated with atopy (any specific IgE -0.3 kU/L) and cigarette smoking. For ages 17 to 42 years, proportions of incident "asthma" and incident "wheeze without asthma" associated with atopy, adjusted for sex and smoking, were estimated to be 34% (95% confidence interval [CI], 26%-42%) and 5% (95% CI, 1%-9%), respectively, whereas proportions associated with cigarette smoking, adjusted for sex and atopy, were estimated to be 13% (95% CI, 0%-26%) and 34% (95% CI, 27%-40%), respectively. Among participants with no reported wheezing illness at ages 17 to 23 or 33 years, wheeze prevalence at the age of 42 years was positively associated with symptoms in childhood.

CONCLUSIONS

Onset and relapse of wheezing illness in adult life seem to be similarly affected by atopy and cigarette smoking, although the nature of these effects may differ between asthma and wheeze without asthma. Children who apparently "outgrow" early wheezing illness remain at increased risk for relapse or recurrence during midlife.

Sequencing and association analysis of the type 1 diabetes-linked region on chromosome 10p12-q11

Background

In an effort to locate susceptibility genes for type 1 diabetes (T1D) several genome-wide linkage scans have been undertaken. A chromosomal region designated IDDM10 retained genome-wide significance in a combined analysis of the main linkage scans. Here, we studied sequence polymorphisms in 23 Mb on chromosome 10p12-q11, including the putative IDDM10 region, to identify genes associated with T1D.

Results

Initially, we resequenced the functional candidate genes, CREM and SDF1, located in this region, genotyped 13 tag single nucleotide polymorphisms (SNPs) and found no association with T1D. We then undertook analysis of the whole 23 Mb region. We constructed and sequenced a contig tile path from two bacterial artificial clone libraries. By comparison with a clone library from an unrelated person used in the Human Genome Project, we identified 12,058 SNPs. We genotyped 303 SNPs and 25 polymorphic microsatellite markers in 765 multiplex T1D families and followed up 22 associated polymorphisms in up to 2,857 families. We found nominal evidence of association in six loci (P = 0.05 – 0.0026), located near the PAPD1 gene. Therefore, we resequenced 38.8 kb in this region, found 147 SNPs and genotyped 84 of them in the T1D families. We also tested 13 polymorphisms in the PAPD1 gene and in five other loci in 1,612 T1D patients and 1,828 controls from the UK. Overall, only the D10S193 microsatellite marker located 28 kb downstream of PAPD1 showed nominal evidence of association in both T1D families and in the case-control sample (P = 0.037 and 0.03, respectively).

Conclusion

We conclude that polymorphisms in the CREM and SDF1 genes have no major effect on T1D. The weak T1D association that we detected in the association scan near the PAPD1 gene may be either false or due to a small genuine effect, and cannot explain linkage at the IDDM10 region.

IL23R variation determines susceptibility but not disease phenotype in inflammatory bowel disease

BACKGROUND & AIMS

Identification of inflammatory bowel disease (IBD) susceptibility genes is key to understanding pathogenic mechanisms. Recently, the North American IBD Genetics Consortium provided compelling evidence for an association between ileal Crohn's disease (CD) and the IL23R gene using genome-wide association scanning. External replication is a priority, both to confirm this finding in other populations and to validate this new technique. We tested for association between IL23R and IBD in a large independent UK panel to determine the size of the effect and explore subphenotype correlation and interaction with CARD15.

METHODS

Eight single nucleotide polymorphism markers in IL23R tested in the North American study were genotyped in 1902 cases of Crohn's disease (CD), 975 cases of ulcerative colitis (UC), and 1345 controls using MassARRAY. Data were analyzed using chi(2) statistics, and subgroup association was sought.

RESULTS

A highly significant association with CD was observed, with the strongest signal at coding variant Arg381Gln (allele frequency, 2.5% in CD vs 6.2% in controls [P = 1.1 x 10(-12)]; odds ratio, 0.38; 95% confidence interval, 0.29-0.50). A weaker effect was seen in UC (allele frequency, 4.6%; odds ratio, 0.73; 95% confidence interval, 0.55-0.96). Analysis accounting for Arg381Gln suggested that other loci within IL23R also influence IBD susceptibility. Within CD, there were no subphenotype associations or evidence of interaction with CARD15.

CONCLUSIONS

This study shows an association between IL23R and all subphenotypes of CD with a smaller effect on UC. This extends the findings of the North American study, providing clear evidence that genome-wide association scanning can successfully identify true complex disease genes.

A method to address differential bias in genotyping in large-scale association studies

In a previous paper we have shown that, when DNA samples for cases and controls are prepared in different laboratories prior to high-throughput genotyping, scoring inaccuracies can lead to differential misclassification and, consequently, to increased false-positive rates. Different DNA sourcing is often unavoidable in large-scale disease association studies of multiple case and control sets. Here, we describe methodological improvements to minimise such biases. These fall into two categories: improvements to the basic clustering methods for identifying genotypes from fluorescence intensities, and use of "fuzzy" calls in association tests in order to make appropriate allowance for call uncertainty. We find that the main improvement is a modification of the calling algorithm that links the clustering of cases and controls while allowing for different DNA sourcing. We also find that, in the presence of different DNA sourcing, biases associated with missing data can increase the false-positive rate. Therefore, we propose the use of "fuzzy" calls to deal with uncertain genotypes that would otherwise be labeled as missing.

Prenatal exposures and glucose metabolism in adulthood: are effects mediated through birth weight and adiposity?

OBJECTIVE

Birth weight has been associated with the risk of type 2 diabetes in several studies. We investigated whether prenatal influences on birth weight (gestational age, parity, preeclampsia, prepregnancy BMI, smoking during pregnancy, and socioeconomic position [SEP]) were associated with glucose metabolism in midlife and the role of birth weight for gestational age (BGA) and adult adiposity in mediating these associations.

RESEARCH DESIGN AND METHODS

Data from 7,518 participants of the 1958 British Birth Cohort with information on A1C at age 45 years were analyzed. Associations between prenatal exposures and A1C > or =6% were examined using a series of logistic regression models. The basic model consisted of all prenatal factors (except parity) adjusted for sex and family history of type 2 diabetes. Further adjustments included BGA only, concurrent adiposity only (BMI and waist circumference), and BGA plus adiposity.

RESULTS

In the basic model, preeclampsia (odds ratio 1.78 [95% CI 1.14-2.80]), prepregnancy BMI > or =25 kg/m(2) (1.90 [1.45-2.47]), maternal smoking (1.33 [1.04-1.71]), and manual SEP (1.87 [1.36-2.58]) were independently associated with A1C at 45 years of age. Adjustment for BGA had little impact on the prenatal factors/A1C associations, whereas adjustment for adult adiposity at 45 years substantially reduced associations for prepregnancy BMI, smoking during pregnancy, and SEP.

CONCLUSIONS

Prenatal exposures were related to blood glucose levels in mid-adulthood. Associations for several prenatal factors were largely mediated through adult adiposity but surprisingly not through birth weight. Prenatal exposures are likely to have the strongest effect on glucose metabolism indirectly through their influence on adiposity.

Association of the interleukin-2 receptor alpha (IL-2Ralpha)/CD25 gene region with Graves' disease using a multilocus test and tag SNPs

OBJECTIVE

A small number of immune response genes have been consistently associated with the common autoimmune conditions. Recently, a linkage disequilibrium (LD) mapping approach, using tag single nucleotide polymorphisms (SNPs), identified genetic association between type 1 diabetes (T1D) and the interleukin-2 receptor alpha (IL-2Ralpha)/CD25 gene region on chromosome 10p15. Because certain autoimmune diseases, such as autoimmune thyroid disease (AITD) and T1D cluster together in certain families, we sought to determine if the TID-associated CD25 region was also associated with Graves' disease (GD).

DESIGN

We performed a case-control association study of 20 tag SNPs.

PATIENTS

1896 GD patients were collected from seven major centres in the UK and 1822 geographically matched controls from the 1958 British Birth Cohort.

MEASUREMENTS

The 20 tag SNPs were analysed using a multilocus test to identify an association between GD and the CD25 region. Odds ratios (ORs) were calculated for the tag SNPs, allowing a comparison with previous results for T1D. RESULTS The multilocus test provided statistical evidence of an association between GD and the CD25 region (P = 4.5 x 10(-4)), with the pattern of association of the 20 tag SNPs similar to that found in T1D. CONCLUSIONS Association with GD, as well as that previously reported with T1D, suggests that the CD25 region is acting as a general susceptibility locus for autoimmune disease, and is consistent with a major role for the IL-2-receptor pathway in the development and function of T cells in the control of autoimmunity.

Social gradients in binge drinking and abstaining: trends in a cohort of British adults

OBJECTIVE

To investigate (1) social gradients in non-drinking and binge drinking, and (2) changes in social gradients in drinking with increasing age.

METHODS

British men and women born during the same week in March 1958 were prospectively followed up to adulthood. The frequency and amount of alcohol use were recorded at age 23, 33 and 42 years. Abstainers "never" drank, binge drinkers consumed >or=10 units (men) and >or=7 units (women) per occasion. Educational qualifications and occupation were reported at age 23 and 33 years. Logistic and repeated-measures models were used to investigate associations between social position and drinking status at single and multiple ages in adulthood.

RESULTS

Less educated men and women had greater odds of being non-drinkers at each age in adulthood, with similar gradients at ages 23-42 years. At 23 years of age, men without qualifications had 2.94 times greater odds of non-drinking than men with higher qualifications. Less educated men had greater odds of binge drinking, and gradients did not change at ages 23-42 years. At age 23 years, less educated women had lower odds of binge drinking (odds ratio (OR) 0.67 for women with no qualifications) than women with higher qualifications. By age 42 years, the gradient reversed, and less educated women had higher odds of binge drinking (OR 2.68).

CONCLUSIONS

Stable gradients in non-drinking and trends in gradients in binge drinking may reinforce alcohol-related health inequalities over time.

Hypovitaminosis D in British adults at age 45 y: nationwide cohort study of dietary and lifestyle predictors

BACKGROUND

Increased awareness of the importance of vitamin D to health has led to concerns about the prevalence of hypovitaminosis D in many parts of the world.

OBJECTIVES

We aimed to determine the prevalence of hypovitaminosis D in the white British population and to evaluate the influence of key dietary and lifestyle risk factors.

DESIGN

We measured 25-hydroxyvitamin D [25(OH)D] in 7437 whites from the 1958 British birth cohort when they were 45 y old.

RESULTS

The prevalence of hypovitaminosis D was highest during the winter and spring, when 25(OH)D concentrations <25, <40, and <75 nmol/L were found in 15.5%, 46.6%, and 87.1% of participants, respectively; the proportions were 3.2%, 15.4%, and 60.9%, respectively, during the summer and fall. Men had higher 25(OH)D concentrations, on average, than did women during the summer and fall but not during the winter and spring (P = 0.006, likelihood ratio test for interaction). 25(OH)D concentrations were significantly higher in participants who used vitamin D supplements or oily fish than in those who did not (P < 0.0001 for both) but were not significantly higher in participants who consumed vitamin D-fortified margarine than in those who did not (P = 0.10). 25(OH)D concentrations <40 nmol/L were twice as likely in the obese as in the nonobese and in Scottish participants as in those from other parts of Great Britain (ie, England and Wales) (P < 0.0001 for both).

CONCLUSION

Prevalence of hypovitaminosis D in the general population was alarmingly high during the winter and spring, which warrants action at a population level rather than at a risk group level.

Diabetes risk in British adults in mid life: a national prevalence study of glycated haemoglobin

AIMS

Information on the population at risk of developing Type 2 diabetes in the UK is scarce. We used data from the 1958 British birth cohort to estimate geographical and socio-economic variations in HbA(1c) in mid life.

METHODS

Participants (n = 7799) born in England, Scotland and Wales and currently living in the UK. Individuals were classified according to the presence of Type 2 diabetes and by thresholds of HbA(1c). HbA(1c)> or = 5.5 was used as an indicator for possible subclinical alterations in glucose metabolism.

RESULTS

The majority of the population had HbA(1c) < 5.5% (79.3%); 16.7% had HbA(1c) 5.5-5.9%, 2.0% 6.0-6.9% and 0.6% had HbA(1c)> or = 7.0%. Individuals from manual socio-economic groups and those living in the East of England and Scotland had a higher prevalence of HbA(1c) at or above the upper normal range (5.5%).

CONCLUSIONS

Estimates from this nationwide sample suggest that a proportion of Britons are likely to have subclinical alterations in glucose metabolism by their mid 40s, and this proportion is greater in some socio-economic groups and geographical regions than in others.

Investigation of association between the TRAF family genes and RA susceptibility

OBJECTIVE

The tumour necrosis factor (TNF) receptor-associated factor (TRAF) family is important in activating multiple inflammatory and immune related processes induced by cytokines such as TNFalpha and interleukin-1. These genes therefore represent strong candidate susceptibility factors for rheumatoid arthritis (RA). A study was undertaken to investigate the association between single nucleotide polymorphisms (SNPs) spanning six TRAF genes and RA in a British population.

METHODS

Twenty-three haplotype tagging (ht) SNPs and 26 random SNPs spanning the six TRAF genes were initially tested for association in a cohort of 351 unrelated patients with RA and 368 controls. Any SNPs demonstrating an association were genotyped in further samples. Sequenom MassARRAY technology was preferentially used for genotyping. Both single point and haplotypic analyses were performed.

RESULTS

Forty-four SNPs were successfully genotyped and conformed to Hardy-Weinberg expectation. A single SNP, rs7514863, mapping upstream of the TRAF5 gene and affecting a putative transcription factor binding site, demonstrated a significant association across the entire cohort of 1273 cases with RA compared with 2463 healthy controls (OR for minor T allele 1.2 (95% CI 1.06 to 1.36), p = 0.005). The association was stronger in the subgroup carrying at least one copy of the shared epitope alleles (OR 1.43 (95% CI 1.18 to 1.73), p = 0.0003).

CONCLUSION

These findings provide evidence for the association of an SNP upstream of a strong candidate RA susceptibility gene, TRAF5, in a large cohort of patients and controls. Further association and functional studies are required to investigate the role of this variant, or one in linkage disequilibrium with it, in RA disease causation.

Health inequalities with the National Statistics-Socioeconomic classification: disease risk factors and health in the 1958 British birth cohort

BACKGROUND

Health inequalities using the new National Statistics socioeconomic classification (NS-SEC) have so far been assessed using only general measures of health, with little known about inequality for specific health outcomes. Preliminary analyses show that self-employed workers, distinguished for the first time by NS-SEC, show increased mortality risk in the last 5 years of working life. We examined health inequalities for multiple disease risk factors and health outcomes, with particular reference to cardiorespiratory risk in the self-employed.

METHODS

8952 participants in the 1958 British birth cohort with information on adult occupation and disease risk factors at 45 years. Systolic and diastolic blood pressure, body mass index, glycosylated haemoglobin, total and high density lipoprotein (HDL) cholesterol, triglycerides, fibrinogen, C-reactive protein, tissue plasminogen activator (t-PA), von Willebrand factor, total immunoglobulin E (IgE), one-second forced expiratory volume, 4 kHz hearing threshold, visual impairment, depressive symptoms, anxiety, chronic widespread pain and self-rated health were measured.

RESULTS

Routine workers had poorer health than professional workers for most outcomes examined, except HDL cholesterol, triglycerides, t-PA and IgE in men; total cholesterol and IgE in women. Patterns of inequality varied depending on the outcome but rarely showed linear trend across the classes. Relative to professionals, own account workers (self-employed) did not show consistently increased levels of cardiorespiratory risk markers.

CONCLUSIONS

Health inequalities are seen with NS-SEC across diverse outcomes for men and women. In mid-life, self-employed workers do not have an adverse cardiorespiratory risk profile.

Lifecourse influences on health among British adults: effects of region of residence in childhood and adulthood

BACKGROUND

It has been suggested that early life exposures are important determinants of geographical variations in adult diseases. We examined inter-regional migrants in Britain to evaluate the relative importance of early and recent exposures for adult cardiorespiratory risk factors, mental ill-health and sensory function.

METHODS

A total of 9023 persons born throughout England, Scotland and Wales during 1 week in 1958 were followed periodically through childhood into adulthood. At 44-45 years, height, body mass index (BMI), blood pressure (BP), glycosylated haemoglobin, total and high-density lipoprotein (HDL) cholesterol, triglycerides, fibrinogen, total immunoglobulin E (IgE), one-second forced expiratory volume (FEV1), hearing threshold at 4 kHz, visual impairment, symptoms of depression and anxiety, and chronic widespread pain were measured. Analysis of migration between 12 regions included 3125 cohort members who were examined in a region different to their birthplace.

RESULTS

Height, BMI, diastolic BP (DBP), FEV1, log-transformed IgE and hearing threshold varied by region among non-migrants (each P < 0.05). Among inter-regional migrants, the spatial associations with current region, independent of birthplace, followed closely the geographical pattern shown among non-migrants for BMI, DBP and FEV1 (each P < 0.001). In contrast, of the 15 outcomes, only adult height was related to region of birth, after adjustment for region of examination (P = 0.002)

CONCLUSIONS

Although individual disease risk is predicted by early life factors, early exposures do not explain regional variations in cardiovascular and respiratory risk factors among middle-aged adults in Britain. Geographical inequalities in cardiorespiratory health are more strongly related to factors associated with region of examination that influence obesity, BP and ventilatory function.

Life-course influences on health in British adults: effects of socio-economic position in childhood and adulthood

BACKGROUND

Little evidence exists on the role of socio-economic position (SEP) in early life on adult disease other than for cardiovascular mortality; data is often retrospective. We assess whether childhood SEP influences disease risk in mid-life, separately from the effect of adult position, and establish how associations vary across multiple measures of disease risk.

METHODS

Prospective follow-up to adulthood of all born in England, Scotland and Wales during 1 week in 1958, and with medical data at age 45 years (n = 9377). Outcomes include: blood pressure, body mass index (BMI), glycosylated haemoglobin (HbA1c), total and high density lipoprotein (HDL) cholesterol, triglycerides, fibrinogen, total immunoglobulin E (IgE), one-second forced expiratory volume (FEV1), hearing threshold (4 kHz), visual impairment, symptoms of depression and anxiety, chronic widespread pain.

RESULTS

Social class in childhood was associated with blood pressure, BMI, HbA1c, HDL cholesterol, triglycerides, fibrinogen, FEV1, hearing threshold, depressive symptoms and chronic widespread pain, with a general trend of deteriorating health from class I to V. Adult social class was also associated with these measures. Mutually adjusted analyses of child and adult social class suggest that both contribute to disease risk in mid-life: in general, associations for childhood class were as strong as for adult class. Individuals with a manual class at both time-points tended to have the greatest health deficits in adulthood.

CONCLUSIONS

Adverse SEP in childhood is associated with a poorer health profile in mid-adulthood, independently of adult social position, and across diverse measures of disease risk and physical and mental functioning.

Are common symptoms in childhood associated with chronic widespread body pain in adulthood?: Results from the 1958 british birth cohort study

OBJECTIVE

Studies have shown that common symptoms in childhood predict the onset of chronic widespread pain in the short term. However, it is unknown whether this association persists into adulthood. The aim of the current study was to examine, prospectively, whether children with common symptoms experience an increased risk of chronic widespread pain as adults.

METHODS

Information on vomiting/bilious attacks, abdominal pain, and headaches/migraine was collected on 10,453 7-year-old children, by maternal report. Similar data were gathered when the children were ages 11 years and 16 years. Body pain at age 45 years was assessed by postal questionnaire. Poisson regression was used to examine chronic widespread pain in relation to childhood symptom reporting.

RESULTS

Of the 10,453 subjects on whom data were obtained when they were children, 7,470 participated at age 45 years (71.5%). Children with multiple symptoms at age 7 years experienced a 50% increased risk of chronic widespread pain (relative risk 1.5 [95% confidence interval 1.03, 2.3]). This relationship persisted after adjustment for sex, recent psychological distress, and childhood and current socioeconomic status, and after excluding children with major illnesses that might have explained early symptom reporting. A similar relationship with symptoms at ages 11 and 16 years was observed, although this was not associated with additional risk compared with that found with the presence of symptoms at age 7 years. However, despite a modest increase in risk, the presence of multiple symptoms at early ages was uncommon (<1.5%), and therefore, the associated population attributable risk was low (<1%).

CONCLUSION

Multiple common symptoms in childhood are associated with an increased risk of chronic widespread pain in adulthood. However, the magnitude of this increased risk is modest, and reports of multiple symptoms in childhood are uncommon. Thus the "early pain pathway" phenomenon is applicable only to a small proportion of individuals with chronic widespread pain.

Investigation of the MHC2TA gene, associated with rheumatoid arthritis in a Swedish population, in a UK rheumatoid arthritis cohort

OBJECTIVE

A recent study of rheumatoid arthritis (RA) showed an association with a functional single-nucleotide polymorphism (SNP) mapping to the promoter region of the MHC2TA gene on chromosome 16p13 in a Swedish population. Interestingly, evidence for linkage to this region has been detected previously in a subgroup of UK RA families carrying 2 copies of shared epitope (SE) alleles. Therefore, we undertook this study to investigate the association of the MHC2TA gene promoter with RA in a UK Caucasian population.

METHODS

Association with 5 SNPs spanning the promoter region of the MHC2TA gene was investigated in 813 UK RA patients and 532 population controls. Association with a functional putative RA-causal polymorphism (-168*G/A [rs3087456]) was tested in a total of 1,401 UK RA patients and 2,475 controls. Genotyping was performed using a Sequenom MassArray platform. Estimated haplotype frequencies were generated using the expectation-maximization algorithm and compared between patients and controls.

RESULTS

All SNPs were in Hardy-Weinberg equilibrium. No evidence for association was found, either with the putative RA-causal polymorphism (-168*G/A) or with the other SNPs tested. Haplotype analysis revealed extensive linkage disequilibrium across the promoter region but no evidence for association. Stratifying the data set by carriage of SE alleles did not alter the conclusions.

CONCLUSION

A functional polymorphism of the MHC2TA gene locus previously associated with RA in a European population has not been associated with RA in a UK population. These findings do not provide support for the notion that this gene plays a major role in the etiology of RA.

Associations of early growth and adult adiposity with patterns of salivary cortisol in adulthood

CONTEXT

Early growth and obesity are associated with adult chronic disease. A suspected mediator is the hypothalamic-pituitary-adrenal axis and cortisol regulation. Our prior hypothesis was that cortisol levels are affected by anthropometry at several life stages.

OBJECTIVE

The objective of the study was to assess whether prenatal and postnatal growth and adiposity are associated with adult cortisol levels, and whether early growth and adiposity are related to later cortisol through adult body size.

DESIGN

Weight, head circumference (birth), height, and body mass index (BMI) (7 yr); and height, BMI (33 yr), and waist-hip ratio (WHR) (45 yr) were measured in the 1958 British birth cohort.

SETTING

All study subjects were born in England, Scotland, and Wales in 1 wk in March 1958.

PARTICIPANTS

A total of 6,470 participants with salivary cortisol were gathered from 12,069 invitees (54%) at 45 yr.

MAIN OUTCOME MEASURES

Two saliva samples on 1 d were collected: 45 min postwaking (t1) and 3 h later (t2). Three cortisol outcomes were measured: t1 level, area-under-curve, and abnormal t1-t2 pattern.

RESULTS

WHR was associated with all cortisol measures: among men over the WHR range 0.81-1.05, t1 cortisol decreased by approximately 3 nmol/liter, and the risk of an abnormal t1-t2 pattern increased by 77%; for women, over the WHR range 0.69-0.93, the risk of an abnormal t1-t2 pattern increased by 74%. For childhood measures, among males, increasing 7-yr BMI was associated with decreased t1 cortisol and increased risk of an abnormal t1-t2 pattern. Poorer prenatal growth in women, and postnatal growth in both sexes, was associated with increasing area-under-curve.

CONCLUSIONS

Smaller head circumference, shorter stature, lower BMI, and WHR are associated with higher cortisol levels.

Drinking histories of self-identified lifetime abstainers and occasional drinkers: findings from the 1958 British Birth Cohort Study

AIMS

To investigate the validity of retrospective items used to distinguish people who have rarely or never consumed alcohol.

METHODS

The 1958 British Birth Cohort Study has followed 9377 individuals until age 45. Previous drinking (at 16, 23, 33 and 42 years) was investigated for two groups of 45-year-old non-drinkers, those reporting never having consumed alcohol ('never drinkers', n = 143, 1.5%), and having only consumed very infrequently ('occasional-only drinkers', n = 1149, 12.3%).

RESULTS

67% of never drinkers previously reported drinking, 25% were past weekly/daily drinkers; 56% of occasional-only drinkers reported weekly/daily consumption. The validity of the retrospective items was progressively questionable when presumed to cover longer time periods.

CONCLUSIONS

Substantial measurement error was evident when identifying 'occasional-only' and 'never' drinkers using retrospective items covering the lifecourse. Researchers investigating potential health benefits associated with moderate drinking need to incorporate more sophisticated methods when identifying sub-groups of non-drinkers.

Inferring myopia over the lifecourse from uncorrected distance visual acuity in childhood

AIM

To report the usefulness of uncorrected distance visual acuity (DVA) at 16 years to "screen" for myopia status and to assess the lifetime risk of myopia, based on a national birth cohort.

METHODS

1867 members of the 1958 British birth cohort for whom there were data on acuity at 16 years had autorefraction, as part of a biomedical survey, at 45 years. Reduced uncorrected DVA at age 16 years (6/12 or worse in both eyes) was compared with adult refraction (spherical equivalent).

RESULTS

Only a quarter of individuals in the population studied who had developed myopia by 45 years of age had reduced acuity at 16 years of age. Notably, half of all adults with moderate myopia (-2.99 to -5.99) and 31% (11/35) with severe myopia (> or =-6) had good uncorrected DVA in both eyes at 16 years of age. Thus, sensitivities were low, ranging from 16% for all myopia (cut-off point spherical equivalent -0.5) to 69% for severe myopia (cut-off point spherical equivalent -6). However, a high (91%) lifetime probability of primary myopia (spherical equivalent > or =-0.5) given a reduced uncorrected DVA at 16 years was found.

CONCLUSION

In this population, reduced uncorrected DVA in childhood is an inaccurate and inappropriate intermediate "phenotype" for capturing adult myopia status. However, our findings support assessment of DVA in secondary school children as an effective method of identifying refractive error (both myopia and hypermetropia).

Vitamin D status and glucose homeostasis in the 1958 British birth cohort: the role of obesity

OBJECTIVE

Obesity is a well-known risk factor for vitamin D deficiency. We evaluated the interrelationship between vitamin D status, body size, and glucose homeostasis, measured by HbA1c (A1C).

RESEARCH DESIGN AND METHODS

Data are from the survey of the 45-year-old 1958 British birth cohort (2002-2004). Information on A1C, 25-hydroxyvitamin D [25(OH)D; an indicator of vitamin D status], and BMI was collected from 7,198 Caucasian subjects.

RESULTS

25(OH)D was < 75 nmol/l in 80% of the obese subjects (BMI > or = 30 kg/m2) versus 68% of the other subjects (P < 0.0001). Serum 25(OH)D decreased and A1C increased by increasing BMI (P < 0.0001 for both comparisons). There was a nonlinear association between 25(OH)D and A1C: a steep linear decrease in A1C by 25(OH)D until 65 nmol/l and only smaller decreases with further increases. There was evidence for effect modification by BMI in the association between 25(OH)D and A1C (P < 0.0001), and differences appeared stronger for participants with higher compared with lower BMIs. After adjustment for sex, season, geographical location, physical activity, and social class, percent change in A1C by 10-nmol/l increase in 25(OH)D was -0.21 (95% CI -0.31 to -0.11) for BMI < 25 kg/m2, -0.25 (-0.37 to -0.13) for BMI 25-29.9 kg/m2, -0.65 (-0.95 to -0.34) for BMI 30-34.9 kg/m2, and -1.37 (-2.09 to -0.64) for BMI > or = 35 kg/m2.

CONCLUSIONS

Body size was a strong determinant for 25(OH)D, with concentrations being suboptimal in most obese participants. Randomized controlled trials [using dosages sufficient to improve 25(OH)D also for the obese] are required to determine whether clinically relevant improvements in glucose metabolism can be obtained by vitamin D supplementation.

Beta2-adrenoceptor polymorphisms and asthma from childhood to middle age in the British 1958 birth cohort: a genetic association study

BACKGROUND

Functionally relevant polymorphisms of the beta2-adrenoceptor gene (ADRB2) are common in white populations, but their contribution to the burden of airways disease in the population is uncertain. We aimed to relate the long-term prevalence of asthma or wheeze to functional coding region polymorphisms in the ADRB2 gene.

METHODS

The British 1958 birth cohort consisted of all people born in Britain during a week in 1958. Asthma, wheezy bronchitis, and wheezing were ascertained by interview at ages 7, 11, 16, 23, 33, and 42 years, and lung function tests at 35 and 45 years. DNA samples from 8018 participants in the 45-year follow-up were genotyped for three coding variants in the ADRB2 gene. We extend the follow-up of this nationwide cohort by a further 10 years and relate asthma prevalence, prognosis, and lung function to functional coding region polymorphisms in the ADRB2 gene in the cohort members who contributed DNA samples. We also compared and combined our findings with those reaching significance in two previous meta-analyses.

FINDINGS

Half the cohort (4105 of 8018) had some history of wheezing illness by age 42 years. Neither lifetime prevalence nor age at onset were related to ADRB2 coding variants. However, the common polymorphisms Arg16Gly (rs1042713, Arg 16 allele frequency 36.3%) and Gln27Glu (rs1042714, Glu 27 allele frequency 44.6%) were significantly associated with persistence of asthmatic symptoms from childhood to middle age. Among homozygotes for the Arg16-Gln27 haplotype at these loci, 19.3% (41 of 212) childhood wheezers had five or more wheezing episodes in the past year at age 42, compared with 11.9% (71 of 599) with no copy of this haplotype. However, only 3% of all frequent adult wheezing was statistically attributable to this haplotype. The less common Thr164Ile polymorphism (rs1800888, Ile allele frequency 1.5%) was not a major predictor of either frequency or prognosis of asthma. Our data do not support the findings of previous meta-analyses when considered in isolation or when combined with their contributory studies.

INTERPRETATION

ADRB2 polymorphisms might predict a small component of the long-term prognosis in childhood asthma, but are not important determinants of asthma incidence or prevalence in the British population.

A genome-wide association study of nonsynonymous SNPs identifies a type 1 diabetes locus in the interferon-induced helicase (IFIH1) region

In this study we report convincing statistical support for a sixth type 1 diabetes (T1D) locus in the innate immunity viral RNA receptor gene region IFIH1 (also known as mda-5 or Helicard) on chromosome 2q24.3. We found the association in an interim analysis of a genome-wide nonsynonymous SNP (nsSNP) scan, and we validated it in a case-control collection and replicated it in an independent family collection. In 4,253 cases, 5,842 controls and 2,134 parent-child trio genotypes, the risk ratio for the minor allele of the nsSNP rs1990760 A --> G (A946T) was 0.86 (95% confidence interval = 0.82-0.90) at P = 1.42 x 10(-10).

Discovery, linkage disequilibrium and association analyses of polymorphisms of the immune complement inhibitor, decay-accelerating factor gene (DAF/CD55) in type 1 diabetes

Background

Type 1 diabetes (T1D) is a common autoimmune disease resulting from T-cell mediated destruction of pancreatic beta cells. Decay accelerating factor (DAF, CD55), a glycosylphosphatidylinositol-anchored membrane protein, is a candidate for autoimmune disease susceptibility based on its role in restricting complement activation and evidence that DAF expression modulates the phenotype of mice models for autoimmune disease. In this study, we adopt a linkage disequilibrium (LD) mapping approach to test for an association between the DAF gene and T1D.

Results

Initially, we used HapMap II genotype data to examine LD across the DAF region. Additional resequencing was required, identifying 16 novel polymorphisms. Combining both datasets, a LD mapping approach was adopted to test for association with T1D. Seven tag SNPs were selected and genotyped in case-control (3,523 cases and 3,817 controls) and family (725 families) collections.

Conclusion

We obtained no evidence of association between T1D and the DAF region in two independent collections. In addition, we assessed the impact of using only HapMap II genotypes for the selection of tag SNPs and, based on this study, found that HapMap II genotypes may require additional SNP discovery for comprehensive LD mapping of some genes in common disease.

Association of the FCRL3 gene with rheumatoid arthritis: a further example of population specificity?

Association of a functional promoter polymorphism mapping to the Fc receptor-like 3 (FCRL3) gene has recently been reported and replicated with rheumatoid arthritis (RA) in Japanese populations. The aim of this study was to investigate association of the FCRL3 gene with RA in UK subjects. DNA was available from 1065 patients with RA and 2073 population controls from the UK. Four single nucleotide polymorphism (SNP) markers (FCRL3-169*C/T (fclr3_3, rs7528684), fclr3_4 (rs11264799), fclr3_5 (rs945635), fclr3_6 (rs3761959)) all previously associated with RA in a Japanese population were genotyped in 761 RA samples and 484 controls. In the remaining samples, only the putative disease causal polymorphism, FCRL3-169*C/T, was tested. Genotyping was performed using either the Sequenom MassArray iPlex platform or a 5' Allelic discrimination assay (Taqman, ABI). Extensive linkage disequilibrium was present across the promoter SNPs genotyped (r2 values = 0.60-0.98). Allele frequencies did not differ between RA cases and controls either for the putative disease causal polymorphism (odds ratio FCRL3-169*C allele = 0.97 (0.87-1.07), p = 0.51) or for the other SNPs tested. Similarly, no association was detected with RA using haplotype analysis or when stratification by shared epitope carriage or by presence of rheumatoid factor was undertaken. This study was powered to detect an effect size of 1.24 or greater for the FCRL3-169*C/T functional promoter polymorphism but no evidence for association was detected, suggesting that this gene will not have a substantial effect in determining susceptibility to RA in populations of Northern European descent.

Physical activity and change in body mass index from adolescence to mid-adulthood in the 1958 British cohort

BACKGROUND

Prevention of obesity has focused on childhood as a target period. Our aim was to assess whether frequency of adolescent physical activity affected subsequent body mass index (BMI) gain through to mid-adulthood.

METHODS

The British birth cohort of all births in 1 week in March 1958, includes information on physical activity frequency and BMI for several ages, 11-45 years. We examined relationships between activity in adolescence and trajectories of BMI between 16 years (or 23 years) and 45 years using multi-level models. Effects of change in activity on BMI and on change in BMI were tested using ANOVA.

RESULTS

Physical activity at 11 years had no effect on the BMI trajectories, in males or females. More active females at 16 years gained BMI more slowly than others, by 0.007 kg/m2/year per activity category over the period 16-45 years, whereas the most active males gained BMI faster than others, by 0.005 kg/m2/year per activity category. This effect in males was not evident on the BMI trajectory from 23 to 45 years. Consistent with these analyses, change in activity was associated with change in BMI in females, e.g. females active at 16 and 42 years gained less BMI than inactive females (2.1 vs 2.5 kg/m2/10 years). Results for males were inconsistent over the time periods examined.

CONCLUSIONS

Physical activity may lessen the gains in BMI from adolescence onwards, but relationships vary with age, and in later adolescence show opposite effects for males and females. Decreasing activity between adolescence and mid-adulthood in males, and inactivity in both life stages in females may increase BMI gain.