DNA methylation levels associated with race and childhood asthma severity

ABSTRACT

Objective: Asthma is a common chronic childhood disease worldwide. Socioeconomic status, genetic predisposition and environmental factors contribute to its incidence and severity. A disproportionate number of children with asthma are economically disadvantaged and live in substandard housing with potential indoor environmental exposures such as cockroaches, dust mites, rodents and molds. These exposures may manifest through epigenetic mechanisms that can lead to changes in relevant gene expression. We examined the association of global DNA methylation levels with socioeconomic status, asthma severity and race/ethnicity. Methods: We measured global DNA methylation in peripheral blood of children with asthma enrolled in the Kansas City Safe and Healthy Homes Program. Inclusion criteria included residing in the same home for a minimum of 4 days per week and total family income of less than 80% of the Kansas City median family income. DNA methylation levels were quantified by an immunoassay that assessed the percentage of 5-methylcytosine. Results: Our results indicate that overall, African American children had higher levels of global DNA methylation than children of other races/ethnicities (p = 0.029). This difference was more pronounced when socioeconomic status and asthma severity were coupled with race/ethnicity (p = 0.042) where low-income, African American children with persistent asthma had significantly elevated methylation levels relative to other races/ethnicities in the same context (p = 0.006, Hedges g = 1.14). Conclusion: Our study demonstrates a significant interaction effect among global DNA methylation levels, asthma severity, race/ethnicity, and socioeconomic status.

KEYWORDS:

• DNA methylation
• persistent asthma
• socioeconomic status
• race/ethnicity

Acknowledgements

The authors wish to acknowledge the Center for Environmental Health at Children's Mercy Hospital for their assistance with collection of the demographic data. The members include Ryan Allenbrand MFS, Erica Forrest MS RRT, Anita DiDonna, Luke Gard EHS, and Tanisha Webb RRT.

Declaration of interest

The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.

Funding

The collection of demographic data was funded by the U.S. Department of Housing and Urban Development MOLHH0159-07.