The researchers used a special statistical method for their analysis. To do this, they looked at the connection between genetic information and asthma and problems with the digestive tract. If the genetic information is related to both diseases in a highly characteristic way, conclusions can be drawn about the cause and effect relationship. "With reference to the discoverer of the laws of heredity, Gregor Mendel, we speak of a Mendelian randomisation study," explains Dr. Dennis Freuer. The statistician at the Chair of Epidemiology at the University of Augsburg is the first author of the publication.

The researchers analysed data from two large genetic studies called GWAS (the acronym stands for "genome-wide association study"). In a GWAS, the complete genetic material (the genome) of hundreds of thousands of people is combed through for changes that are associated with a specific disease. "We examined a GWAS on asthma with genetic information from around 300,000 men and women, and one on gastrointestinal diseases that included more than 450,000 people," says Freuer.

Connection with adolescent asthma

The Augsburg researchers now combined this data in such a way that they were able to draw conclusions about the relationship between the two diseases. "We were able to show that people who develop asthma in their youth are more likely to develop reflux disease, stomach ulcers or irritable bowel syndrome later on," explains Prof. Dr. Christine Meisinger from the Chair of Epidemiology. "The asthma is causally related to disorders of the digestive tract." This connection does not apply to forms of asthma that only manifest themselves in adulthood. On the other hand, the risk of inflammatory bowel diseases, such as Crohn's disease, was also reduced in those affected.
It is still unclear how the lungs and digestive tract interact in these diseases. "We need further studies to answer this question," Meisinger emphasises. Nevertheless, the result is also of great relevance from the point of view of those affected. On the one hand, it draws attention to a connection that could contribute to a better understanding of how asthma and gastrointestinal diseases develop over the long term. "In addition, our study shows that we should take a closer look at children with asthma in order to diagnose stomach ulcers or irritable bowel syndrome in their later lives at an early stage and, if necessary, treat them promptly," says Meisinger.

Publication:

Freuer, D., Linseisen, J. & Meisinger, C. Asthma and the risk of gastrointestinal disorders: a Mendelian randomization study. BMC Med 20, 82 (2022).

Link to the publication