Better understanding of how genes make us prone to allergies

The United States Centers for Disease Control and Prevention reports that allergies rank as the sixth most prevalent cause of chronic illness in the U.S., resulting in an annual expenditure exceeding $18 billion. While previous research has established a strong genetic basis for allergies and identified specific genetic sequence variations which predispose for these chronic diseases, how our DNA can affect our chances of developing an allergy remains unclear. But understanding this could lead to improved research and potential new treatments.

By using modern genomics and imaging techniques, a collaborative team of researchers co-led by Penn's Golnaz Vahedi, PhD, an associate professor of Genetics, and Jorge Henao-Mejia, MD, PhD, an associate professor of Pathology and Laboratory Medicine, found that the ETS1 protein plays a role in controlling a type of immune cell called CD4+ T helper cells, which are important in allergic reactions and help orchestrate the immune response by activating and coordinating other immune cells.

DNA interactions within the genomic segment encompassing the ETS1 gene control how much of the ETS1 protein is made.

"We discovered that these interactions, work like a dimmer switch," said Vahedi. "When there are changes in the DNA in this area, it can mess up the dimmer switch, causing problems with controlling the ETS1 protein. This can lead to imbalances in our immune cells and cause allergic inflammations."

While there has been progress in understanding genetic traits that follow predictable patterns, like those passed down from parents, it's been more challenging to understand conditions that involve many different genes and are common in populations. These complex conditions cannot be explained by simply "turning off" one gene. Instead, they may be caused by small changes in the DNA that affect how genes work together. However, researchers still do not know much about how these changes in DNA relate to how our genes are organized or how they affect how genes are expressed in most complex diseases.

"This work demonstrates how small differences in our DNA can disturb the balance between our immune cells, resulting in significant observable characteristics in patients. This phenomenon may occur in other common diseases such as autoimmune disorders," said Henao-Mejia.

Other co-authors of this study include Aditi Chandra, Sora Yoon, and Michael Michieletto. This research was funded by the National Institutes of Health (R01AI168240, UC4 DK112217, U01 DK112217, R01 HL145754, U01 DK127768, U01 DA052715, R01 HL136572), the Burroughs Welcome Fund, the Chan Zuckerberg Initiative Award, W. W. Smith Charitable Trust, the Sloan Foundation, and the PEW Charitable Trust.