Asthma is a complex respiratory condition affecting millions of Americans. And now research is shifting toward the role genetics plays in causing asthma and how this might help create new treatments. Dr. James Thompson, HealthCentral’s asthma expert, discusses how genetics influences asthma control, severity and risk.
You recently wrote about the different phenotypes of asthma patients. Can you expand on this?**
Our genetic makeup is the blueprint for all of our body tissues, internal organs, skin, bones, muscles and nerves. All body processes begin with genetic instruction. That said, asthma is a disease which has a genetic origin. This accounts for the many different asthma subtypes now being identified. Unlike some other lung disorders, such as cystic fibrosis, asthma is more complex genetically. Research indicates multiple genes play a role. Understanding how genetics affects asthma is still a work in progress.
How does genetics play a role in a patient’s asthma severity?
Certain genes increase the likelihood of having allergic asthma. It is widely accepted that allergic asthma tends to be more severe. Research is also looking at how genetics increases a patient’s vulnerability to certain viral and bacterial infections. Some genes may lead to steroid resistance or resistance to reliever medications, such as Albuterol. On the other hand, certain asthma patients may possess genes which make them less likely to be bothered by certain irritants, chemicals, infections or allergic triggers compared to other asthma patients.
Can a patient comply with therapies and treatment yet still have severe asthma due to their genetic phenotype?
Yes, if they are resistant to steroids—either inhaled, oral, or intravenous—they may have more severe asthma. If they don’t respond as well to reliever medication or other anti-inflammatory treatments, compliance with medications may still fall short of good asthma control.
Can a patient’s asthma phenotype change as they age?
Phenotype may possibly change based on environmental influences and age. Some genes may be dormant at first and lead to more or less severe asthma down the road. We already know that young males in the U.S. have more severe asthma, on average, compared to young females. But if you look at adult females at increasing ages, asthma severity is higher compared to the same age group of males.
Can people “grow out” of childhood asthma?
We don’t believe people actually grow out of asthma. But if the genes are less active, or are suppressed by other genes or external influences (allergy shots), a remission period may occur. We prefer the term “remission” since asthma has been known to resurface after years of being inactive. This may relate to the influence of multiple genes interacting with each other or environmental influences.
Can someone be born with a genetic predisposition for asthma?
We think all asthma patients have a genetic predisposition. However, studies with identical twins prove that other factors besides genetics are responsible for asthma. The fact that asthma does not occur 100 percent of the time in identical twins proves thatother influences on gene expression, possibly environmental, may play a role.
Is a child of a parent with asthma at risk for also developing the disease?
Yes, this is true. Reports vary but some estimate children of asthmatic parents have a 50 percent chance if one parent has asthma and 66 percent chance if both have it.
How do you see genetics playing a role in asthma treatment/prevention in the future?
It will likely be the distant future in regards to pharmacogenetics [the study of genetic information and how it relates to drug therapy]. But the near future is promising for research looking at phenotypes of asthma that respond to certain types of available medications. New medications may target certain asthma phenotypes based on research currently underway.