Allergies Genetics Risk Factors

An estimated 50 million people in North America suffer from allergies. An allergic reaction occurs when a person’s immune system overreacts to a normally harmless foreign object, called an allergen. Common allergens include:

  • dander
  • dust mites
  • mold
  • pollen.

Symptoms of Allergies

Allergic rhinitis, or hay fever, is the most common type of allergy. Allergic rhinitis primarily affects the nasal passages, causing them to become inflamed. Symptoms of allergies typically include:

  • itchy ears, nose and throat
  • postnasal drip
  • runny nose
  • sneezing
  • stuffy nose.

Allergies can also manifest as allergic conjunctivitis (red, itchy eyes) or eczema.

Allergy Risk Factors

Some people at higher risk for developing allergies than others. Genetics play a large role in allergy risk. Some scientists believe that many allergic reactions are due to a gene that promotes production of interleukin-4. Interleukin-4 is a protein that plays a large role in allergic reactions. Studies have indicated that African-Americans often have very high levels of interleukin-4, and they also have higher rates of allergies and asthma than other ethnic groups.

Lifestyle choices can also affect your risk of developing allergies. For example, people who smoke or grow up in households with cigarette smoke have a high allergy risk. Babies who are bottle-fed rather than breastfed also have a higher-than normal risk of having allergies.

Other risk factors include:

  • allergen exposure at an early age
  • birth during high-pollen season
  • having at least one parent with nasal allergies
  • premature infants.

How Allergies Are Diagnosed

If you experience allergy symptoms, you may wish to get an allergy test to pinpoint the exact cause of your allergy. One type of allergy tests is a skin test. Skin tests are generally carried out by applying a small amount of an allergen to your skin, scratching or pricking the skin to allow exposure, and studying the skin’s reaction.

Skin tests are the most common type of allergy test. Risks include the potential of having an allergic reaction during the test, but nasal allergies are generally not life-threatening. Results of a skin test are immediate.

Doctors sometimes recommend a RAST test if a skin test cannot be performed for some reason. With a RAST test, the physician draws a sample of your blood and sends it off to a lab, where it is exposed to different allergens. RAST test results are usually available in one to two weeks, and you won’t run the risk of having an allergic reaction during the allergy test.

Preventing Allergy Risk

Expectant parents may wonder if there’s any way to limit their child’s risk of developing an allergy. While there’s no 100 percent guarantee, there are steps you can take to minimize your child’s risk of having allergies.

First, do not smoke during pregnancy and limit your exposure to secondhand smoke. Do not let anyone smoke around your child. Keep your family pet–some studies have suggested that exposure to a dog or cat at an early age may boost the child’s immune system against allergies to pet dander later in life.

Reduce dust mites in your home by investing in allergen-resistant bedding and dehumidifiers. Consider replacing carpets with hardwood floors.

If you’re pregnant, take a fish oil supplement and get plenty of Vitamin E. Taking probiotics during pregnancy can reduce the risk of childhood allergies. Finally, breastfeed your child for as long as possible. Studies have shown that breastfeeding dramatically reduces your child’s risk of developing allergies or asthma.


Ansorge, R. and Metcalf, E. (2006). Allergy risk factors. Retrieved March 30, 2009, from the Yahoo! Health Web site: risk-factors/prevention–22593.html.

Gordon, D. (2008). Preventing childhood asthma and allergies. Retrieved March 30, 2009, from the Revolution Health Web site: allergies.

Optum Health (2008). RAST test. Retrieved March 30, 2009, from the Optum Health Web site: Test?archiveChanne l=Home/Health Hubs/Type2HealthHub/Respiratory Diseases/SubTopi cs/Respiratory Diseases /Allergies