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Background: A recent genome-wide association study (GWAS) identified 99 loci that contain genetic risk variants shared between asthma, hay fever, and eczema. Many more risk loci shared between these common allergic diseases remain to be discovered, which could point to new therapeutic opportunities., Objective: We sought to identify novel risk loci shared between asthma, hay fever, and eczema by applying a gene-based test of association to results from a published GWAS that included data from 360,838 subjects., Methods: We used approximate conditional analysis to adjust the results from the published GWAS for the effects of the top risk variants identified in that study. We then analyzed the adjusted GWAS results with the EUGENE gene-based approach, which combines evidence for association with disease risk across regulatory variants identified in different tissues. Novel gene-based associations were followed up in an independent sample of 233,898 subjects from the UK Biobank study., Results: Of the 19,432 genes tested, 30 had a significant gene-based association at a Bonferroni-corrected P value of 2.5 × 10 -6 . Of these, 20 were also significantly associated (P < .05/30 = .0016) with disease risk in the replication sample, including 19 that were located in 11 loci not reported to contain allergy risk variants in previous GWASs. Among these were 9 genes with a known function that is directly relevant to allergic disease: FOSL2, VPRBP, IPCEF1, PRR5L, NCF4, APOBR, IL27, ATXN2L, and LAT. For 4 genes (eg, ATXN2L), a genetically determined decrease in gene expression was associated with decreased allergy risk, and therefore drugs that inhibit gene expression or function are predicted to ameliorate disease symptoms. The opposite directional effect was observed for 14 genes, including IL27, a cytokine known to suppress T H 2 responses., Conclusion: Using a gene-based approach, we identified 11 risk loci for allergic disease that were not reported in previous GWASs. Functional studies that investigate the contribution of the 19 associated genes to the pathophysiology of allergic disease and assess their therapeutic potential are warranted., (Copyright © 2018 American Academy of Allergy, Asthma & Immunology. Published by Elsevier Inc. All rights reserved.)

Background: Atopic dermatitis (AD) is a common inflammatory skin disease. Previous studies have revealed shared genetic determinants among different inflammatory disorders, suggesting that markers associated with immune-related traits might also play a role in AD., Objective: We sought to identify novel genetic risk factors for AD., Methods: We examined the results of all genome-wide association studies from a public repository and selected 318 genetic markers that were significantly associated with any inflammatory trait. These markers were considered candidates and tested for association with AD in a 3-step approach including 7 study populations with 7130 patients with AD and 9253 control subjects., Results: A functional amino acid change in the IL-6 receptor (IL-6R Asp358Ala; rs2228145) was significantly associated with AD (odds ratio [OR], 1.15; P = 5 × 10(-9)). Interestingly, investigation of 2 independent population-based birth cohorts showed that IL-6R 358Ala specifically predisposes to the persistent form of AD (ORpersistent AD = 1.22, P = .0008; ORtransient AD = 1.04, P = .54). This variant determines the balance between the classical membrane-bound versus soluble IL-6R signaling pathways. Carriers of 358Ala had increased serum levels of soluble IL-6R (P = 4 × 10(-14)), with homozygote carriers showing a 2-fold increase. Moreover, we demonstrate that soluble IL-6R levels were higher in patients with AD than in control subjects (46.0 vs 37.8 ng/mL, P = .001). Additional AD risk variants were identified in RAD50, RUNX3, and ERBB3., Conclusion: Our study supports the importance of genetic variants influencing inflammation in the etiology of AD. Moreover, we identified a functional genetic variant in IL6R influencing disease prognosis and specifically predisposing to persistent AD., (Copyright © 2013 American Academy of Allergy, Asthma & Immunology. Published by Mosby, Inc. All rights reserved.)

Background: IL-31 is a novel cytokine that, when overexpressed in transgenic mice, induces severe itching dermatitis resembling human eczema., Objective: We aimed to evaluate the importance of polymorphisms in the human IL-31 gene (IL31) in the genetic susceptibility to eczema., Methods: We sequenced the entire IL-31 gene, including the promoter region, and determined the haplotype structure. Single nucleotide polymorphisms tagging the main haplotypes were genotyped in 3 independent European populations comprising 690 affected families. An association analysis of IL31 gene variants with atopic and nonatopic eczema was performed., Results: We found significant association of a common IL31 haplotype with the nonatopic type of eczema in all 3 study populations (combined P = 4.5 x 10(-5)). Analysis of PBMCs in healthy individuals revealed a strong induction IL31 mRNA expression on stimulation with anti-CD3 and anti-CD28 that was 3.8-fold higher in individuals homozygous for the risk haplotype (AA) in contrast to non-A haplotype carriers, suggesting that altered regulation of IL-31 gene expression is the disease-causing factor., Conclusion: Our results lend strong support to an important role of IL-31 in the pathogenesis of nonatopic eczema., Clinical Implications: This study presents the first genetic risk factor for the nonatopic type of eczema and indicates a primary role of IL-31-induced pruritus in the initiation of this disease, thus proposing a new target for the prevention and therapy of eczema.

Background: Childhood eczema often precedes the development of asthma and allergic rhinitis in the so-called atopic march. Recently, 2 loss-of-function mutations in the gene encoding the epidermal barrier protein filaggrin were reported to be predisposing factors for eczema and concomitant asthma, suggesting a possible role in disease transition., Objective: We aimed to assess the importance of filaggrin loss-of-function mutations in the susceptibility to eczema and associated clinical phenotypes., Methods: The filaggrin mutations were genotyped and tested for association with allergic disorders in 2 large European populations including 1092 children with eczema., Results: Highly significant association of the filaggrin null mutations with eczema and concomitant asthma was replicated. Moreover, we found that these mutations predispose to asthma, allergic rhinitis, and allergic sensitization only in the presence of eczema. We show that the presence of 2 filaggrin null alleles is an independent risk factor for asthma in children with eczema, and that the 2 investigated mutations account for about 11% of eczema cases in the German population., Conclusion: These results lend strong support to the role of filaggrin in the pathogenesis of eczema and in the subsequent progression along the atopic march. The fact that previous expression of eczema is a prerequisite for the manifestation of allergic airways disease and specific sensitization highlights the importance of the epidermal barrier in the pathogenesis of these disorders., Clinical Implications: Our results suggest that the maintenance and repair of the epidermal barrier in infants with eczema may prevent the subsequent development of allergic airways disease.

Background: Sensitization to mite allergens represents a prominent feature of atopy and an important predictor of bronchial asthma., Objective: It was the intention of this study to define genetic loci linked to mite sensitization because these could represent the genetic basis of the important atopic component of asthma., Methods: We studied a multiethnic white population of 99 families, including 224 sib pairs sensitized to Dermatophagoides pteronyssinus. A genome-wide candidate-region search was performed that covered potential asthma and atopy regions., Results: As for nonparametric linkage (NPL) analysis, 14 of the candidate regions showed evidence for linkage (NPL > 2.0), and 4 of them showed prominent linkage (NPL > 3.0). However, there were substantial ethnic differences. Maximizing the LOD score analysis identified candidate regions with suspected dominant and recessive mode of inheritance. Furthermore, genetic imprinting models provided significant evidence for linkage in the 8p23 region and revealed potential maternal imprinting. The regions found are distinct to those in asthma searches that have been found to be linked to asthma, as well to other inflammatory diseases. In addition, we could not find linkage to the HLA region. By different cutoff points of the phenotype definition, the IL cluster showed evidence of being linked to the degree of sensitization rather than to sensitization per se., Conclusion: The results indicate that the genetic basis of the atopic component of asthma is different from that of the inflammatory component. Furthermore, it seems reasonable to assume that specific sensitizations are influenced by distinct genetic variants leading to their initiation versus those leading to their enhancement.