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Epigenetic biomarkers of childhood asthma

Published online: December 21, 2018

Asthma is the most common chronic disease of childhood.  Genome-wide association studies have identified many genetic variants related to asthma, but these explain only a small portion of disease risk. There is increasing interest in the hypothesis that epigenetic variation (modifications to DNA that do not change the genetic sequence) influences asthma. The best studied epigenetic modification is methylation. The availability of high-throughput methylation platforms with reasonable epigenome-wide coverage has enabled agnostic epigenome-wide association studies (EWAS) of methylation in relation to asthma that can identify novel loci and thus provide new insights into disease pathogenesis.

In this large-scale international collaboration published in The Journal of Allergy and Clinical Immunology (JACI), Reese and authors performed coordinated epigenome-wide association studies of blood DNA methylation in relation to childhood asthma and then combined the results using meta-analysis. This work was done within the Pregnancy and Childhood Epigenetics (PACE) consortium of birth and child cohorts. Reese and authors performed two different meta-analyses. The first was prospective and examined methylation at birth in relation to the development of childhood asthma. The second was cross-sectional, examining methylation assessed at the same time point as childhood asthma.

In the prospective analysis, the authors found nine genetic loci differentially methylated in newborns who later developed asthma compared with those who did not. In the cross-sectional analysis of children, they found many more loci differentially methylated in relation to asthma.   Comparing these findings from blood, a mix of cell types, to analyses of asthma in relation to differential methylation of blood eosinophils (inflammatory cells that tend to be elevated in asthma) and cells lining the nose (nasal respiratory epithelium), the authors found that many of the findings were consistent between blood and these two purified tissues directly relevant to asthma.

Novel loci differentially methylated in newborns represent potential biomarkers of the risk of developing asthma by school age. The cross-sectional associations in children may reflect both risk for and effects of asthma. In addition to identifying potential biomarkers of asthma, these findings may shed light on new mechanisms of asthma pathogenesis.

The Journal of Allergy and Clinical Immunology (JACI) is an official scientific journal of the AAAAI and is the most-cited journal in the field of allergy and clinical immunology.