Rachel E. Story

Food allergy (FA) affects 2%-10% of US children and is a growing clinical and public health problem. Here we conduct the first genome-wide association study of well-defined FA, including specific subtypes (peanut, milk and egg) in 2,759 US participants (1,315 children and 1,444 parents) from the Chicago Food Allergy Study, and identify peanut allergy (PA)-specific loci in the HLA-DR and -DQ gene region at 6p21.32, tagged by rs7192 (P=5.5 × 10(-8)) and rs9275596 (P=6.8 × 10(-10)), in 2,197 participants of European ancestry. We replicate these associations in an independent sample of European ancestry. These associations are further supported by meta-analyses across the discovery and replication samples. Both single-nucleotide polymorphisms (SNPs) are associated with differential DNA methylation levels at multiple CpG sites (P<5 × 10(-8)), and differential DNA methylation of the HLA-DQB1 and HLA-DRB1 genes partially mediate the identified SNP-PA associations. This study suggests that the HLA-DR and -DQ gene region probably poses significant genetic risk for PA.

To cite this article: Matsui EC, Sampson HA, Bahnson HT, Gruchalla RS, Pongracic JA, Teach SJ, Gergen PJ, Bloomberg GR, Chmiel JF, Liu AH, Kattan M, Sorkness CA, Steinbach SF, Story RE, Visness CM, on behalf of the Inner‐city Asthma Consortium. Allergen‐specific IgE as a biomarker of exposure plus sensitization in inner‐city adolescents with asthma. Allergy 2010; 65 : 1414–1422. Abstract Background: Relationships among allergen‐specific IgE levels, allergen exposure and asthma severity are poorly understood since sensitization has previously been evaluated as a dichotomous, rather than continuous characteristic. Methods: Five hundred and forty‐six inner‐city adolescents enrolled in the Asthma Control Evaluation study underwent exhaled nitric oxide (FE NO ) measurement, lung function testing, and completion of a questionnaire. Allergen‐specific IgE levels and blood eosinophils were quantified. Dust samples were collected from the participants’ bedrooms for quantification of allergen concentrations. Participants were followed for 12 months and clinical outcomes were tracked. Results: Among sensitized participants, allergen‐specific IgE levels were correlated with the corresponding settled dust allergen levels for cockroach, dust mite, and mouse ( r = 0.38, 0.34, 0.19, respectively; P &lt; 0.0001 for cockroach and dust mite and P = 0.03 for mouse), but not cat ( r = −0.02, P = 0.71). Higher cockroach‐, mite‐, mouse‐, and cat‐specific IgE levels were associated with higher FE NO concentrations, poorer lung function, and higher blood eosinophils. Higher cat, dust mite, and mouse allergen‐specific IgE levels were also associated with an increasing risk of exacerbations or hospitalization. Conclusions: Allergen‐specific IgE levels were correlated with allergen exposure among sensitized participants, except for cat. Allergen‐specific IgE levels were also associated with more severe asthma across a range of clinical and biologic markers. Adjusting for exposure did not provide additional predictive value, suggesting that higher allergen‐specific IgE levels may be indicative of both higher exposure and a greater degree of sensitization, which in turn may result in greater asthma severity.

PURPOSE OF REVIEW: Childhood asthma and obesity are significant public health problems. The prevalence of both disorders has increased considerably in the past decade. This review will highlight recent publications regarding the nature of the relationship between asthma and obesity and the clinical effects of obesity in children with asthma. RECENT FINDINGS: Most prospective studies suggest that obesity increases the risk of subsequent asthma. Possible mechanisms for the relationship between asthma and obesity include airway inflammation, mechanical changes associated with obesity, changes in airway hyper-responsiveness, and changes in physical activity and diet. Most studies suggest that obesity increases the clinical severity of asthma and decreases quality of life in children with asthma. More research is required to further define and clarify the relationship between asthma and obesity in children. SUMMARY: There are many questions and few answers regarding the relationship between asthma and obesity in children. Additional studies are needed to clarify the relationship between the two epidemics so that effective interventions can be developed to improve the health and lives of children with both asthma and obesity.