A study about the relationship between asthma and obesity, which uses a community-based twin registry from the University of Washington in Seattle, has found a strong genetic link between the two disorders, according to findings published in the December issue of the Journal of Allergy and Clinical Immunology.
While this study replicates previous findings that have shown asthma to be more common in obese individuals, it goes on to show that the largest portion of the association between the two disorders could be explained by a common set of genetic factors.
Dr. Teal Hallstrand, assistant professor of pulmonary and critical care medicine at the University of Washington in Seattle, led the study, which compared the frequency of asthma and obesity in both identical and fraternal, or non-identical, twins. The researchers analyzed 1001 identical and 383 fraternal same-sex twin pairs within the University of Washington Twin Registry. They found that the largest portion of the association between asthma and obesity could be attributed to a common set of genetic factors, referred to as genetic pleiotropy, which implies that the same genetic factors may have a causal influence on both asthma and obesity.
Asthma and obesity are increasingly common disorders, especially in Westernized societies. A fundamental question about the relationship between obesity and asthma is whether the association between these two disorders is predominantly genetic or environmental.
The researchers also report that the effects of environmental exposures on asthma and obesity are likely to occur primarily in the context of a specific genetic background, referred to as gene-by-environment effects.