Genetic pleiotropy between asthma and obesity in a community-based sample of twins

J Allergy Clin Immunol. 2005 Dec;116(6):1235-41. doi: 10.1016/j.jaci.2005.09.016. Epub 2005 Nov 8.


Background: Asthma and obesity are common conditions that are strongly associated. This association might be due to shared genetic or environmental causes.

Objective: We sought to determine whether a shared genetic cause is responsible for the association between asthma and obesity and to estimate the magnitude of shared genetic cause.

Methods: The analyses were performed with 1001 monozygotic and 383 dizygotic same-sex twin pairs within the University of Washington Twin Registry. The presence of asthma was determined by self-report of a physician diagnosis of asthma, and body mass index (BMI) was calculated by using self-reported height and weight. Obesity was defined as a BMI of 30 or greater. The association between asthma and BMI was assessed by means of mixed-effects ordinal regression. Twin correlations examined the association of asthma and obesity. Univariate and bivariate structural equation models estimated the components of variance attributable to genetic and environmental effects.

Results: A strong association between asthma and BMI was identified in the sample population (P < .001). Substantial heritability was detected for asthma (53%) and obesity (77%), which is indicative of additive genetic influences on each disorder. The best-fitting model of shared components of variance indicated that 8% of the genetic component of obesity is shared with asthma.

Conclusion: The covariation between obesity and asthma is predominantly caused by shared genetic risk factors for both conditions.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Aged
  • Asthma / etiology
  • Asthma / genetics*
  • Body Mass Index
  • Diseases in Twins / genetics*
  • Humans
  • Middle Aged
  • Models, Genetic
  • Obesity / etiology
  • Obesity / genetics*
  • Risk Factors
  • Twins, Dizygotic
  • Twins, Monozygotic