Predictive value of food sensitization and filaggrin mutations in children with eczema

BACKGROUND

It was reported that in infants with eczema and food sensitization, the presence of a filaggrin (FLG) null mutation predicts future asthma with a specificity and positive predictive value of 100%.

OBJECTIVES

We sought to evaluate the predictive value of food sensitization and food allergy, FLG haploinsufficiency, and their combination in infants with early-onset eczema for persistent eczema and childhood asthma.

METHODS

The German Infant Nutritional Intervention (GINI) and Influence of Lifestyle-related Factors on the Immune System and the Development of Allergies in Childhood (LISA) birth cohorts, as well as a collection of 65 cases of early-onset eczema with and without food allergy were investigated.

RESULTS

The risk for asthma was significantly increased by food sensitization (positive diagnostic likelihood ratios [PLRs] of 1.9 [95% CI, 1.1-3.4] in the GINI cohort and 5.5 [95% CI, 2.8-10.8] in the LISA cohort) and the presence of an FLG mutation (PLRs of 2.9 [95% CI, 1.2-6.6] in the GINI cohort and 2.8 [95% CI, 1.0-7.9] in the LISA cohort) with a rather high specificity (79.1% and 92.9% in the GINI cohort and 89.0% and 91.7% in the LISA cohort, respectively) but low sensitivity (40.0% and 39.3% in the GINI cohort and 31.6% and 23.5% in the LISA cohort, respectively). Likewise, the risk for persistent eczema was increased. In the clinical cases neither food allergy nor FLG mutations had a significant effect. The combination of both parameters did not improve prediction and reached positive predictive values of 52.3% (GINI cohort), 66.9% (LISA cohort), and 30.6% (clinical cases), assuming an asthma prevalence in children with early eczema of 30%.

CONCLUSION

Early food sensitization and the presence of an FLG mutation in infants with early eczema increase the risk for later asthma, but the combination of the 2 factors does not represent a clinically useful approach to reliably identify children at risk.

Missing heritability in the tails of quantitative traits? A simulation study on the impact of slightly altered true genetic models

OBJECTIVE

Genome-wide association studies have identified robust associations between single nucleotide polymorphisms and complex traits. As the proportion of phenotypic variance explained is still limited for most of the traits, larger and larger meta-analyses are being conducted to detect additional associations. Here we investigate the impact of the study design and the underlying assumption about the true genetic effect in a bimodal mixture situation on the power to detect associations.

METHODS

We performed simulations of quantitative phenotypes analysed by standard linear regression and dichotomized case-control data sets from the extremes of the quantitative trait analysed by standard logistic regression.

RESULTS

Using linear regression, markers with an effect in the extremes of the traits were almost undetectable, whereas analysing extremes by case-control design had superior power even for much smaller sample sizes. Two real data examples are provided to support our theoretical findings and to explore our mixture and parameter assumption.

CONCLUSIONS

Our findings support the idea to re-analyse the available meta-analysis data sets to detect new loci in the extremes. Moreover, our investigation offers an explanation for discrepant findings when analysing quantitative traits in the general population and in the extremes.

Occupational exposure to organic dust increases lung cancer risk in the general population

BACKGROUND

Organic dust is a complex mixture of particulate matter from microbial, plant or animal origin. Occupations with exposure to animal products have been associated with an increased lung cancer risk, while exposure to microbial components (eg, endotoxin) has been associated with a decreased risk. To date there has not been a comprehensive evaluation of the possible association between occupational organic dust exposure (and its specific constituents) and lung cancer risk in the general population.

METHODS

The SYNERGY project has pooled information on lifetime working and smoking from 13 300 lung cancer cases and 16 273 controls from 11 case-control studies conducted in Europe and Canada. A newly developed general population job-exposure matrix (assigning no, low or high exposure to organic dust, endotoxin, and contact with animals or fresh animal products) was applied to determine level of exposure. ORs for lung cancer were estimated by logistic regression, adjusted for age, sex, study, cigarette pack-years, time since quitting smoking, and ever employment in occupations with established lung cancer risk.

RESULTS

Occupational organic dust exposure was associated with increased lung cancer risk. The second to the fourth quartile of cumulative exposure showed significant risk estimates ranging from 1.12 to 1.24 in a dose-dependent manner (p<0.001). This association remained in the highest quartile after restricting analyses to subjects without chronic obstructive pulmonary disease or asthma. No association was observed between lung cancer and exposure to endotoxin or contact with animals or animal products.

CONCLUSION

Occupational exposure to organic dust was associated with increased lung cancer risk in this large pooled case-control study.

Population-genetic comparison of the Sorbian isolate population in Germany with the German KORA population using genome-wide SNP arrays

Background

The Sorbs are an ethnic minority in Germany with putative genetic isolation, making the population interesting for disease mapping. A sample of N = 977 Sorbs is currently analysed in several genome-wide meta-analyses. Since genetic differences between populations are a major confounding factor in genetic meta-analyses, we compare the Sorbs with the German outbred population of the KORA F3 study (N = 1644) and other publically available European HapMap populations by population genetic means. We also aim to separate effects of over-sampling of families in the Sorbs sample from effects of genetic isolation and compare the power of genetic association studies between the samples.

Results

The degree of relatedness was significantly higher in the Sorbs. Principal components analysis revealed a west to east clustering of KORA individuals born in Germany, KORA individuals born in Poland or Czech Republic, Half-Sorbs (less than four Sorbian grandparents) and Full-Sorbs. The Sorbs cluster is nearest to the cluster of KORA individuals born in Poland. The number of rare SNPs is significantly higher in the Sorbs sample. FST between KORA and Sorbs is an order of magnitude higher than between different regions in Germany. Compared to the other populations, Sorbs show a higher proportion of individuals with runs of homozygosity between 2.5 Mb and 5 Mb. Linkage disequilibrium (LD) at longer range is also slightly increased but this has no effect on the power of association studies.

Oversampling of families in the Sorbs sample causes detectable bias regarding higher FST values and higher LD but the effect is an order of magnitude smaller than the observed differences between KORA and Sorbs. Relatedness in the Sorbs also influenced the power of uncorrected association analyses.

Conclusions

Sorbs show signs of genetic isolation which cannot be explained by over-sampling of relatives, but the effects are moderate in size. The Slavonic origin of the Sorbs is still genetically detectable.

Regarding LD structure, a clear advantage for genome-wide association studies cannot be deduced. The significant amount of cryptic relatedness in the Sorbs sample results in inflated variances of Beta-estimators which should be considered in genetic association analyses.

Genetic architecture of circulating lipid levels

Serum concentrations of low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C), triglycerides (TGs) and total cholesterol (TC) are important heritable risk factors for cardiovascular disease. Although genome-wide association studies (GWASs) of circulating lipid levels have identified numerous loci, a substantial portion of the heritability of these traits remains unexplained. Evidence of unexplained genetic variance can be detected by combining multiple independent markers into additive genetic risk scores. Such polygenic scores, constructed using results from the ENGAGE Consortium GWAS on serum lipids, were applied to predict lipid levels in an independent population-based study, the Rotterdam Study-II (RS-II). We additionally tested for evidence of a shared genetic basis for different lipid phenotypes. Finally, the polygenic score approach was used to identify an alternative genome-wide significance threshold before pathway analysis and those results were compared with those based on the classical genome-wide significance threshold. Our study provides evidence suggesting that many loci influencing circulating lipid levels remain undiscovered. Cross-prediction models suggested a small overlap between the polygenic backgrounds involved in determining LDL-C, HDL-C and TG levels. Pathway analysis utilizing the best polygenic score for TC uncovered extra information compared with using only genome-wide significant loci. These results suggest that the genetic architecture of circulating lipids involves a number of undiscovered variants with very small effects, and that increasing GWAS sample sizes will enable the identification of novel variants that regulate lipid levels.

A genome-wide association study identifies LIPA as a susceptibility gene for coronary artery disease

BACKGROUND

eQTL analyses are important to improve the understanding of genetic association results. We performed a genome-wide association and global gene expression study to identify functionally relevant variants affecting the risk of coronary artery disease (CAD).

METHODS AND RESULTS

In a genome-wide association analysis of 2078 CAD cases and 2953 control subjects, we identified 950 single-nucleotide polymorphisms (SNPs) that were associated with CAD at P<10(-3). Subsequent in silico and wet-laboratory replication stages and a final meta-analysis of 21 428 CAD cases and 38 361 control subjects revealed a novel association signal at chromosome 10q23.31 within the LIPA (lysosomal acid lipase A) gene (P=3.7×10(-8); odds ratio, 1.1; 95% confidence interval, 1.07 to 1.14). The association of this locus with global gene expression was assessed by genome-wide expression analyses in the monocyte transcriptome of 1494 individuals. The results showed a strong association of this locus with expression of the LIPA transcript (P=1.3×10(-96)). An assessment of LIPA SNPs and transcript with cardiovascular phenotypes revealed an association of LIPA transcript levels with impaired endothelial function (P=4.4×10(-3)).

CONCLUSIONS

The use of data on genetic variants and the addition of data on global monocytic gene expression led to the identification of the novel functional CAD susceptibility locus LIPA, located on chromosome 10q23.31. The respective eSNPs associated with CAD strongly affect LIPA gene expression level, which was related to endothelial dysfunction, a precursor of CAD.

Abstract 1875: Lung cancer risk among hairdressers in SYNERGY – pooled analysis from case-control studies in Europe and Canada with detailed smoking data

“Occupational exposure as a hairdresser or barber” was classified as probably carcinogenic to humans by the International Agency for Research on Cancer in volume 99 (2010). Small increases in lung cancer risk (20-40%) are found in most cohort studies but without adequate adjustment for smoking. Studies in Scandinavia and the USA show a higher prevalence of smokers among hairdressers than in the general population.

The SYNERGY project has pooled information on lifetime work histories (ISCO-68) and tobacco smoking from 13479 cases and 16350 controls, including 20% women, from 11 case-control studies in 12 European countries and Canada. The original studies were conducted between 1985 and 2005. Odds ratios (OR) for lung cancer and 95% confidence intervals (CI) were estimated by unconditional logistic regression, adjusted for age, sex, study, cigarette pack-years and time since quitting smoking.

Less than 1% of the study population had ever worked as hairdresser or barber (0.89% of cases and 0.74% of controls). Hairdressers and barbers experienced a slight increase in lung cancer risk OR 1.16 (95%CI 0.90-1.49), which disappeared after adjusting for smoking OR 0.97 (95%CI 0.73-1.30). Results by duration of employment showed highest risks in hairdressers with short employment. Results were similar by gender, histology of lung cancer, and for women hairdressers. We observed a slight and non-significant increase in risk for male barbers, particularly in barbers with the longest employment and after adjustment for smoking.

We could not detect an association between having worked as hairdresser or barber and increased lung cancer risk overall after adjusting for smoking. However, among male barbers we observed an increasing risk with increasing duration, although non-significant, after adjusting for tobacco smoking. Final results will include several more studies, and thereby increase the precision of our effect estimates.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 1875. doi:10.1158/1538-7445.AM2011-1875

Abstract 1877: Lung cancer risk in painters: Results from the SYNERGY pooled analysis

“Occupational exposure as a painter” was classified as carcinogenic to humans by the International Agency for Research on Cancer (IARC) based on increased risks of cancers of the lung, bladder, and mesothelioma. Painters are exposed to a mixture of known and suspected lung carcinogens; thus it has been difficult to identify the specific agent(s) contributing to the elevated risk of lung cancer. Although the exposure to occupational carcinogens could differ according to the job duties of a painter, it is unknown whether the risk of lung cancer differs according to the painter type. Data from the SYNERGY study were used to evaluate the risk of lung cancer associated with ever working as a painter, duration of employment, and type of painter (classified according to ISCO and ISIC codes). SYNERGY is a pooled effort of 11 case-control studies in European countries and Canada that includes detailed individual data on smoking for 13389 lung cancer cases and 16384 age- and sex-matched controls. Among the cases and controls, there were 462 and 383 painters, respectively. Multivariable unconditional logistic regression models were adjusted for age, gender, centre, tobacco pack-years, and occupational exposures to asbestos, silica, polycyclic aromatic hydrocarbons, chromium VI and nickel as assessed by a job-exposure matrix. An odds ratio (OR) of 1.31 (95% CI, 1.12-1.45) was associated with ever working as painter and the risk of lung cancer increased with increasing years of employment (p-value for trend = 0.0004). A similar magnitude of effect and trend with duration of employment was observed in construction painters (ISCO 93120/ISIC 5000) but not in automobile painters (ISCO 93960/ISIC 3843,9513). Results were similar when restricted to men but uninformative for women only due to small numbers. There was no significant difference in risk when stratified by histological type and restricted to never smokers. Painters, particularly in the construction industry, are at an increased risk for lung cancer and this risk increases with duration of employment. These results will be further refined by specific type of painter and by including additional studies to increase the precision of the risk estimates.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 1877. doi:10.1158/1538-7445.AM2011-1877

Exposure to diesel motor exhaust and lung cancer risk in a pooled analysis from case-control studies in Europe and Canada

RATIONALE

Diesel motor exhaust is classified by the International Agency for Research on Cancer as probably carcinogenic to humans. The epidemiologic evidence is evaluated as limited because most studies lack adequate control for potential confounders and only a few studies have reported on exposure-response relationships.

OBJECTIVES

Investigate lung cancer risk associated with occupational exposure to diesel motor exhaust, while controlling for potential confounders.

METHODS

The SYNERGY project pooled information on lifetime work histories and tobacco smoking from 13,304 cases and 16,282 controls from 11 case-control studies conducted in Europe and Canada. A general population job exposure matrix based on ISCO-68 occupational codes, assigning no, low, or high exposure to diesel motor exhaust, was applied to determine level of exposure.

MEASUREMENTS AND MAIN RESULTS

Odds ratios of lung cancer and 95% confidence intervals were estimated by unconditional logistic regression, adjusted for age, sex, study, ever-employment in an occupation with established lung cancer risk, cigarette pack-years, and time-since-quitting smoking. Cumulative diesel exposure was associated with an increased lung cancer risk highest quartile versus unexposed (odds ratio 1.31; 95% confidence interval, 1.19-1.43), and a significant exposure-response relationship (P value < 0.01). Corresponding effect estimates were similar in workers never employed in occupations with established lung cancer risk, and in women and never-smokers, although not statistically significant.

CONCLUSIONS

Our results show a consistent association between occupational exposure to diesel motor exhaust and increased risk of lung cancer. This association is unlikely explained by bias or confounding, which we addressed by adjusted models and subgroup analyses.

Salivary cortisol in a middle-aged community sample: results from 990 men and women of the KORA-F3 Augsburg study

OBJECTIVE

Analysis of salivary cortisol concentrations and derived indices is increasingly used in clinical and scientific medicine. However, comprehensive data on these parameters in the general population are scarce. The aim of this study was to evaluate the concentrations of salivary cortisol in a large middle-aged community sample and to identify major factors associated with altered hormone levels.

DESIGN

We conducted a cross-sectional study within the Cooperative Health Research in the Region of Augsburg (KORA)-F3 study. A total of 1484 participants aged 50-69 years (52% women) had agreed to provide four saliva samples during a regular weekday.

METHODS

We measured salivary cortisol concentrations at wake-up (F0), (1/2) h (F(1/2)), 8 h (F8), and 14 h (F14) after waking. We calculated cortisol awakening response (CAR), slope, and area under the curve (AUC(G)) of the circadian cortisol secretion. Sociodemographic and clinical characteristics were evaluated by interview and questionnaires, sampling conditions by protocol. In total, 1208 participants returned saliva samples, exclusion criteria left 990 subjects for final analyses.

RESULTS

Salivary cortisol levels were (means+/-s.d.) F0=13.7+/-7.6, F(1/2)=20.5+/-9.8, F8=5.4+/-3.3, and F14=2.0+/-1.8 nmol/l. Earlier sampling times were associated with higher CAR and smaller slope. Cortisol secretion was also influenced by gender and smoking habits. Higher perceived social support was associated with lower AUC(G) and smaller slope.

CONCLUSIONS

We provide data on salivary cortisol concentrations in a large middle-aged community sample. Gender, sampling time, smoking habits, and perceived social support appeared as determinants of cortisol secretion.

CONAN: copy number variation analysis software for genome-wide association studies

BACKGROUND

Genome-wide association studies (GWAS) based on single nucleotide polymorphisms (SNPs) revolutionized our perception of the genetic regulation of complex traits and diseases. Copy number variations (CNVs) promise to shed additional light on the genetic basis of monogenic as well as complex diseases and phenotypes. Indeed, the number of detected associations between CNVs and certain phenotypes are constantly increasing. However, while several software packages support the determination of CNVs from SNP chip data, the downstream statistical inference of CNV-phenotype associations is still subject to complicated and inefficient in-house solutions, thus strongly limiting the performance of GWAS based on CNVs.

RESULTS

CONAN is a freely available client-server software solution which provides an intuitive graphical user interface for categorizing, analyzing and associating CNVs with phenotypes. Moreover, CONAN assists the evaluation process by visualizing detected associations via Manhattan plots in order to enable a rapid identification of genome-wide significant CNV regions. Various file formats including the information on CNVs in population samples are supported as input data.

CONCLUSIONS

CONAN facilitates the performance of GWAS based on CNVs and the visual analysis of calculated results. CONAN provides a rapid, valid and straightforward software solution to identify genetic variation underlying the 'missing' heritability for complex traits that remains unexplained by recent GWAS. The freely available software can be downloaded at http://genepi-conan.i-med.ac.at.

Abstract 3777: Diesel motor exhaust and lung cancer risk in a pooled analysis from case-control studies in Europe and Canada

Introduction: Diesel-motor exhaust (DME) is classified by IARC as probably carcinogenic to humans. The epidemiological evidence is evaluated as limited since many studies lack adequate information on tobacco smoking and only few studies reported on exposure-response relationships. Our objective is to investigate the risk of lung cancer following occupational exposure to DME, while controlling for smoking and potential occupational confounders.

Methods: The SYNERGY project pooled information on lifetime work histories and tobacco smoking from more than 13300 cases and 16300 controls from case-control studies conducted in 12 European countries and Canada. A job exposure matrix based on ISCO codes, assigning no (0), low (1) or high (2) exposure to DME was applied to determine level of exposure to DME. Cumulative exposure was defined as: ∑(level2 * duration). Odds ratios (OR) of lung cancer and 95% confidence intervals (CI) were estimated by unconditional logistic regression, adjusted for age, sex, study, pack-years and time since quitting smoking, and ever employment in a “Group A” job, i.e. occupations with established lung cancer risk.

Results: Workers exposed to low levels of occupational DME exposure had an increased risk of lung cancer after 40 years of exposure OR 1.31 (95% CI 1.14-1.51), while workers exposed to high DME levels experienced a similar risk already after short duration (&lt;10 years) OR 1.29, 95% CI 1.15-1.46. Cumulative DME exposure showed a significant exposure-response trend (p-value &lt;0.000) with an OR of 1.31 (95% CI 1.20-1.44) in the highest quartile. These results were similar in workers never employed in “Group A“ jobs, lending support to the assumption that confounding due to other occupational exposures was not responsible for the observed risk. Analyses in sub-populations of women and never-smokers also indicated an increased risk of lung cancer following occupational DME exposure.

Conclusion: Our results indicate that occupational exposure to DME is associated with an increased risk of lung cancer.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 3777.

[Epidemiological research on environmental health risks and their economic consequences]

In environmental health research, methods for quantitative analysis of human population studies data are gaining importance. In recent years, it has been realized that they can also provide an important link to the economic view on environmental health effects. In this review, fundamental concepts and methods from environmental epidemiology and health economics are presented and it is shown how they can be linked in order to support environmental policy decisions. In addition, the characteristics of environmental epidemiology and the role of epidemiologic studies in risk assessment are discussed. From the economic point of view, cost-of-illness studies and cost effectiveness studies are the main approaches, and we have placed special focus on methods of monetary valuation of health effects that are generally proposed in the environmental context. Two conceptually differing strategies to combine epidemiologic and economic evidence are presented: the environmental attributable fraction model as a top-down approach and the impact pathway approach which follows a bottom-up analysis strategy. Finally, two examples are used to illustrate the application of these concepts and methods: health risks caused by fine particle air pollution and their costs, and the cost-effectiveness of radon exposure reduction policies.

Association of a variant in the muscarinic acetylcholine receptor 2 gene (CHRM2) with nicotine addiction

Genetic factors contribute to the overall risk of developing nicotine addiction, which is the major cause of preventable deaths in western countries. However, knowledge regarding specific polymorphisms influencing smoking phenotypes remains scarce. In the present study we provide evidence that a common single nucleotide polymorphism (SNP) in the 5' untranslated region of CHRM2, the gene coding for the muscarinic acetylcholine receptor 2 is associated with nicotine addiction. CHRM2 was defined as a candidate gene for nicotine addiction based on previous evidence that linked variations in CHRM2 to alcohol and drug dependence. A total of more than 5,500 subjects representative of the German population were genotyped and assessed regarding their smoking habits. The impact of three SNPs in CHRM2 on smoking behavior/nicotine addiction was investigated using logistic regression models or a quasi-Poisson regression model, respectively. We found the T allele of SNP rs324650 to be associated with an increased risk of smoking/nicotine dependence according to three different models, the recessive models of regular or heavy smokers vs. never-smokers (odds ratio 1.17 in both analyses) and according to the Fagerström index of nicotine addiction. In the analysis stratified by gender this association was only found in females. Our data provide further evidence that variations in CHRM2 may be associated with the genetic risk of addiction in general or with certain personality traits that predispose to the development of addiction. Alternatively, variations in CHRM2 could modulate presynaptic auto-regulation in cholinergic systems and may thereby affect an individual's response to nicotine more specifically.

Recurrent microdeletions at 15q11.2 and 16p13.11 predispose to idiopathic generalized epilepsies

Idiopathic generalized epilepsies account for 30% of all epilepsies. Despite a predominant genetic aetiology, the genetic factors predisposing to idiopathic generalized epilepsies remain elusive. Studies of structural genomic variations have revealed a significant excess of recurrent microdeletions at 1q21.1, 15q11.2, 15q13.3, 16p11.2, 16p13.11 and 22q11.2 in various neuropsychiatric disorders including autism, intellectual disability and schizophrenia. Microdeletions at 15q13.3 have recently been shown to constitute a strong genetic risk factor for common idiopathic generalized epilepsy syndromes, implicating that other recurrent microdeletions may also be involved in epileptogenesis. This study aimed to investigate the impact of five microdeletions at the genomic hotspot regions 1q21.1, 15q11.2, 16p11.2, 16p13.11 and 22q11.2 on the genetic risk to common idiopathic generalized epilepsy syndromes. The candidate microdeletions were assessed by high-density single nucleotide polymorphism arrays in 1234 patients with idiopathic generalized epilepsy from North-western Europe and 3022 controls from the German population. Microdeletions were validated by quantitative polymerase chain reaction and their breakpoints refined by array comparative genomic hybridization. In total, 22 patients with idiopathic generalized epilepsy (1.8%) carried one of the five novel microdeletions compared with nine controls (0.3%) (odds ratio = 6.1; 95% confidence interval 2.8-13.2; chi(2) = 26.7; 1 degree of freedom; P = 2.4 x 10(-7)). Microdeletions were observed at 1q21.1 [Idiopathic generalized epilepsy (IGE)/control: 1/1], 15q11.2 (IGE/control: 12/6), 16p11.2 IGE/control: 1/0, 16p13.11 (IGE/control: 6/2) and 22q11.2 (IGE/control: 2/0). Significant associations with IGEs were found for the microdeletions at 15q11.2 (odds ratio = 4.9; 95% confidence interval 1.8-13.2; P = 4.2 x 10(-4)) and 16p13.11 (odds ratio = 7.4; 95% confidence interval 1.3-74.7; P = 0.009). Including nine patients with idiopathic generalized epilepsy in this cohort with known 15q13.3 microdeletions (IGE/control: 9/0), parental transmission could be examined in 14 families. While 10 microdeletions were inherited (seven maternal and three paternal transmissions), four microdeletions occurred de novo at 15q13.3 (n = 1), 16p13.11 (n = 2) and 22q11.2 (n = 1). Eight of the transmitting parents were clinically unaffected, suggesting that the microdeletion itself is not sufficient to cause the epilepsy phenotype. Although the microdeletions investigated are individually rare (<1%) in patients with idiopathic generalized epilepsy, they collectively seem to account for a significant fraction of the genetic variance in common idiopathic generalized epilepsy syndromes. The present results indicate an involvement of microdeletions at 15q11.2 and 16p13.11 in epileptogenesis and strengthen the evidence that recurrent microdeletions at 15q11.2, 15q13.3 and 16p13.11 confer a pleiotropic susceptibility effect to a broad range of neuropsychiatric disorders.

Replication of restless legs syndrome loci in three European populations

BACKGROUND

Restless legs syndrome (RLS) is associated with common variants in three intronic and intergenic regions in MEIS1, BTBD9, and MAP2K5/LBXCOR1 on chromosomes 2p, 6p and 15q.

METHODS

Our study investigated these variants in 649 RLS patients and 1230 controls from the Czech Republic (290 cases and 450 controls), Austria (269 cases and 611 controls) and Finland (90 cases and 169 controls). Ten single nucleotide polymorphisms (SNPs) within the three genomic regions were selected according to the results of previous genome-wide scans. Samples were genotyped using Sequenom platforms.

RESULTS

We replicated associations for all loci in the combined samples set (rs2300478 in MEIS1, p = 1.26 x 10(-5), odds ratio (OR) = 1.47, rs3923809 in BTBD9, p = 4.11 x 10(-5), OR = 1.58 and rs6494696 in MAP2K5/LBXCOR1, p = 0.04764, OR = 1.27). Analysing only familial cases against all controls, all three loci were significantly associated. Using sporadic cases only, we could confirm the association only with BTBD9.

CONCLUSION

Our study shows that variants in these three loci confer consistent disease risks in patients of European descent. Among the known loci, BTBD9 seems to be the most consistent in its effect on RLS across populations and is also most independent of familial clustering.

An evaluation of the genetic-matched pair study design using genome-wide SNP data from the European population

Genetic matching potentially provides a means to alleviate the effects of incomplete Mendelian randomization in population-based gene-disease association studies. We therefore evaluated the genetic-matched pair study design on the basis of genome-wide SNP data (309,790 markers; Affymetrix GeneChip Human Mapping 500K Array) from 2457 individuals, sampled at 23 different recruitment sites across Europe. Using pair-wise identity-by-state (IBS) as a matching criterion, we tried to derive a subset of markers that would allow identification of the best overall matching (BOM) partner for a given individual, based on the IBS status for the subset alone. However, our results suggest that, by following this approach, the prediction accuracy is only notably improved by the first 20 markers selected, and increases proportionally to the marker number thereafter. Furthermore, in a considerable proportion of cases (76.0%), the BOM of a given individual, based on the complete marker set, came from a different recruitment site than the individual itself. A second marker set, specifically selected for ancestry sensitivity using singular value decomposition, performed even more poorly and was no more capable of predicting the BOM than randomly chosen subsets. This leads us to conclude that, at least in Europe, the utility of the genetic-matched pair study design depends critically on the availability of comprehensive genotype information for both cases and controls.

Stress-related maternal factors during pregnancy in relation to childhood eczema: results from the LISA Study

BACKGROUND

Stress has been suggested to impact the onset and exacerbation of eczema and other atopic disorders. Whether early exposure to stress-related factors might exert long-term effects remains to be clarified.

OBJECTIVE

The objective of this study was to investigate whether stress-related maternal factors during pregnancy are associated with childhood eczema during the first 6 years of life.

METHODS

Data from 3004 children from a prospective German birth cohort study (LISA) were analyzed. Information from maternity certificates and questionnaire information on unwanted pregnancy were used to evaluate stress-related maternal factors during pregnancy. Prevalence data for physician-diagnosed eczema were available up to the age of 6 years.

RESULTS

Maternal factors during pregnancy were positively associated with childhood eczema in terms of cumulative prevalence up to the age of 2 years (adjusted odds ratio, 1.48; 95% confidence interval, 0.95-2.30) after adjusting for potential confounders. Beyond the second year no increased risk was observed.

CONCLUSIONS

The results of this study suggest that stress-related maternal factors during pregnancy are associated with an increased risk of childhood eczema during the first 2 years of life. The impact of postnatal stress such as parental divorce or separation on this association could not be clarified. Future studies should therefore further elucidate how prenatal and postnatal stress interact and whether prenatal stress might have a programming effect. If future studies confirm the findings of this study, reducing maternal stress during pregnancy might be a possible target in the primary prevention of eczema during childhood.