title: 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).
  
  
  CONCLUSIONS
  Our study demonstrates a significant interaction effect among global DNA methylation levels, asthma severity, race/ethnicity, and socioeconomic status.
authors.affiliation: a Division of Allergy, Asthma and Immunology , Children's Mercy Hospital , Kansas City , MO , USA.
authors.forename: Marcia A
authors.initials: MA
authors.lastname: Chan
authors.affiliation: b Department of Pediatrics , University of Chicago Medicine, Comer Comer Children's Hospital , Chicago , IL , USA.
authors.forename: Christina E
authors.initials: CE
authors.lastname: Ciaccio
authors.affiliation: a Division of Allergy, Asthma and Immunology , Children's Mercy Hospital , Kansas City , MO , USA.
authors.forename: Nicole M
authors.initials: NM
authors.lastname: Gigliotti
authors.affiliation: a Division of Allergy, Asthma and Immunology , Children's Mercy Hospital , Kansas City , MO , USA.
authors.forename: Mo
authors.initials: M
authors.lastname: Rezaiekhaligh
authors.affiliation: c Department of Exercise Science and Pre-Health Professions , Creighton University , Omaha , NE , USA.
authors.forename: Jacob A
authors.initials: JA
authors.lastname: Siedlik
authors.affiliation: d Center for Environmental Health, Children's Mercy Hospital , Kansas City , MO , USA.
authors.forename: Kevin
authors.initials: K
authors.lastname: Kennedy
authors.affiliation: a Division of Allergy, Asthma and Immunology , Children's Mercy Hospital , Kansas City , MO , USA.
authors.forename: Charles S
authors.initials: CS
authors.lastname: Barnes
mesh_terms: D000293:Adolescent; D001249:Asthma / Q000453:epidemiology / Q000208:ethnology* / Q000235:genetics*; D002648:Child; D002675:Child, Preschool; D019175:DNA Methylation / Q000235:genetics*; D005006:Ethnicity / Q000235:genetics*; D005260:Female; D006801:Humans; D007615:Kansas; D008297:Male; D011203:Poverty; D044469:Racial Groups / Q000235:genetics*; D012720:Severity of Illness Index; D012923:Social Class; D055815:Young Adult
keywords: DNA methylation; persistent asthma; race/ethnicity; socioeconomic status