There is a strong genetic component to asthma, but it's not the only risk factor
- Asthma is genetic and a person who has a parent with asthma is 3-6 times more likely to develop the condition.
- All types of asthma — including adult-onset asthma, allergic asthma, and exercise-induced asthma — is thought to have a genetic component.
- In addition to genetics, other risk factors for asthma include allergies and exercise.
- This article was medically reviewed by Osita Onugha, MD, thoracic surgeon and assistant professor of thoracic surgical oncology at John Wayne Cancer Institute at Providence Saint John's Health Center in Santa Monica, California.
Asthma is a chronic condition that causes your airways to become inflamed leading them to swell and narrow. This makes it harder for you to breathe and can cause dangerous asthma attacks.
Asthma is often linked to other health conditions like hay fever and environmental factors including air pollution. However, research also shows that carrying certain genes can put you at greater risk of developing asthma.
Here's what you need to know about what causes asthma and how it can be passed down through families.
Asthma is genetic
Scientists have identified more than one hundred specific genes that may play a role in whether or not a person develops asthma. In fact, a person with at least one biological parent with asthma is 3 to 6 times more likely to develop the condition than someone whose parents don't have asthma.
However, even if you are born with asthma-related genes, you may not develop asthma unless those genes are "turned on," likely by something in your environment. "Multiple genes may be involved and they could be triggered by a number of factors, such as viral infections," says Stanley Szefler, MD, the Director of the Pediatric Asthma Research Program at Children's Hospital Colorado.
This means that if you have asthma-related genes and suffer a bad respiratory infection as a child, this could kickstart a lifelong asthma condition. However, experts say that more research is needed to fully understand how these genes interact with the environment to cause asthma in the first place.
Doctors have identified several different types of asthma including adult-onset asthma, allergic asthma, and exercise-induced asthma. Scientists have not linked any specific genes to a particular type of asthma, Szefler says. However, there is evidence that every type of asthma has a genetic component.
In a study, published in 2008 in Twin Research and Human Genetics, researchers compared the incidence of asthma in twins to determine how strongly genes affect the likelihood of developing asthma, compared with environmental factors. The results showed that genetics plays a very large role – the genes account for about 70% of your risk of developing asthma.
It's important to remember that even though genes are an important risk factor for asthma:
- You can still get asthma even if you are not genetically predisposed to it.
- If you are genetically predisposed to asthma you won't necessarily develop it.
About half of all asthma sufferers start having symptoms as children age 5 and younger. But for people who develop asthma later in life, genes are less likely to play a role. This may be because some older people develop asthma due to lifestyle choices like smoking.
Other causes and risk factors for asthma
In addition to genetics, asthma may be caused by:
- Allergies: Asthma symptoms can be triggered when you breathe in particles of allergens like mold, pollen, or pet dander. Over 80% of people with asthma also experience hay fever.
- Exercise: Some people experience asthma symptoms only during physical exertion, particularly when the weather is cold and dry.
- Your job: If you work in an environment where you are exposed to dust or chemical fumes in the air, this can cause you to develop asthma over time.
In many cases, experts don't know why some people develop asthma while others don't. However, there are risk factors that can increase your risk. These include:
- Smoking or breathing in secondhand smoke
- Having hay fever or an allergic skin condition like eczema
- Being overweight or obese
- Breathing in car exhaust or other environmental pollution
Prevention and treatment of asthma
There is no way to prevent asthma, even if you start treatment early on after your symptoms develop, says Szefler. Researchers are starting to look at whether using biologic medications containing live bacteria could work to prevent asthma, Szelfer says, "but the results are several years off."
However, even if you can't prevent asthma, there are steps you can take to prevent asthma attacks:
- Take all your medications as prescribed. Don't make any changes without first discussing with your doctor — even if your symptoms improve.
- Schedule regular checkups with your doctor. In particular, let your doctor know if you find yourself relying on an inhaler to relieve your symptoms, as this may be a sign that your asthma is not under control.
- Find out what triggers your asthma symptoms and avoid those triggers as much as possible. Common triggers include tobacco smoke or allergens like pollen and dust.
- Get a flu shot. Coming down a respiratory infection can worsen your asthma symptoms and trigger attacks. You can also fight off illness by taking steps to boost your immune system.
Asthma is an ongoing condition and you should "maintain good medical follow-up to keep the disease under control," Szefler says. You will need to make an individual treatment plan with your doctor, designed to target your symptoms and help avoid your asthma triggers.