Research funded by the National Institutes of Health (NIH) suggests that changes in a small region of chromosome 6 are risk factors for peanut allergy in U.S. children of European descent. The genetic risk area is located among two tightly linked genes that regulate the presentation of allergens and microbial products to the immune system. This study is the first to use a genome-wide screening approach in patients with well-defined food allergy to identify risks for peanut allergy.
The study included children with or without food allergy and their biological parents, more than 2,700 participants. Importantly, the participants with food allergy were clinically diagnosed, allowing researchers to find risks for well-defined food allergy. Previous efforts to identify genetic risks for allergy have relied on skin prick or blood tests, which measure a person's sensitivity to allergens but cannot reliably diagnose food allergy.
The researchers used a genome-wide approach to identify changes to the DNA sequence associated with peanut, egg or milk allergy. While the research team did not identify risks for egg or milk allergy, they found two closely linked areas in the region of the HLA-DR and HLA-DQ genes associated with peanut allergy. Notably, the genetic changes at these locations were associated with epigenetic differences. Epigenetic changes are alterations in the structure of DNA, such as the addition of certain chemical groups to the DNA backbone. Many epigenetic changes determine whether a gene is active or inactive. The authors note that more work is needed to assess how the changes identified in this study contribute to the development of peanut allergy.
The study was funded by NIH's National Institute of Allergy and Infectious Diseases through its Consortium of Food Allergy Research. The research was conducted by investigators from several institutions and was led by Xiaobin Wang, M.D., of Johns Hopkins University.
Hong X, Hao K, Ladd-Acosta C et al. Genome-wide association study identifies peanut allergy-specific loci and evidence of epigenetic mediation in U.S. children. Nature Communications DOI: 10.1038/ncomms7304 (2015).
Marshall Plaut, M.D., chief of the Food Allergy, Atopic Dermatitis and Allergic Mechanisms Section in NIAID's Division of Allergy, Immunology and Transplantation, is available to discuss the findings.
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