The Journal of Allergy and Clinical Immunology
Volume 116, Issue 6 , Pages 1235-1241, December 2005

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

  • Teal S. Hallstrand, MD, MPH

      Affiliations

    • From the Departments of Medicine
    • Corresponding Author InformationReprint requests: Teal S. Hallstrand, MD, MPH, Department of Medicine, Division of Pulmonary and Critical Care, University of Washington, Box 356522, 1959 NE Pacific St, Seattle, WA 98195.
    • ,
  • Mary E. Fischer, PhD

      Affiliations

    • Vietnam Era Twin Registry
    • ,
  • Mark M. Wurfel, MD, PhD

      Affiliations

    • From the Departments of Medicine
    • ,
  • Niloofar Afari, PhD

      Affiliations

    • Psychiatry and Behavioral Sciences, University of Washington
    • University of Washington Twin Registry
    • ,
  • Dedra Buchwald, MD

      Affiliations

    • From the Departments of Medicine
    • University of Washington Twin Registry
    • ,
  • Jack Goldberg, PhD

      Affiliations

    • Epidemiology
    • University of Washington Twin Registry
    • Vietnam Era Twin Registry

Received 2 May 2005; received in revised form 6 September 2005; accepted 7 September 2005. published online 14 November 2005.

Seattle, Wash

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.

Key words: Asthma, obesity, genetic, twin

Abbreviations used: BMI, Body mass index, DZ, Dizygotic, MZ, Monozygotic

 

 Supported by National Institutes of Health grants K23HL04231 (TSH), K23HL72923 (MMW), and U19AI38429 (DB).Disclosure of potential conflict of interest: T. Hallstrand has received grants from Merck and Co. Medical School grant awarded to the University of Washington in 2000 and is on the speakers' bureau for Merck and Co. All others—none disclosed.

PII: S0091-6749(05)02064-6

doi:10.1016/j.jaci.2005.09.016

The Journal of Allergy and Clinical Immunology
Volume 116, Issue 6 , Pages 1235-1241, December 2005