Allergies, Genetics, or Both: What Causes Asthma?

Do We Really Know What Causes Asthma?

What Causes Asthma?

I grew up one of four kids — all with asthma.

My mother can’t remember specifics, but she believes I was diagnosed with asthma as a toddler. I’m 31 now — that’s a lot of years I’ve spent suffering from asthma — and even more years ahead of me that I’ll be dealing with this disease.

I have often wondered, “Why do I have asthma? Why does my ENTIRE FAMILY have asthma?”

Here’s an explanation of what causes asthma — and if it really has a familial tendency.

The Cause

Here’s the truth — according to the National Heart, Lung and Blood Institute (NHLBI), the exact cause of asthma isn’t known.

That being said, there are several theories about what may cause asthma. One such theory is that genetics and environmental factors cause asthma. These factors include:

  • Respiratory infections during childhood
  • Exposure with airborne allergens and/or viruses during infancy and early childhood when immunity is developing
  • Parents with asthma
  • Atopy, or the inherited tendency to develop allergies.

The “hygiene hypothesis” is another theory of causation of asthma. According to the NHLBI, “our Western lifestyle — with its emphasis on hygiene and sanitation — has resulted in changes in our living conditions and an overall decline in infections in early childhood.”

This theory further hypothesizes that, due to the decrease in exposure to illness, immune systems do not develop as fully as they had in the past, leaving them susceptible to atopy and asthma.


The Genetic Link

Asthma is commonly thought of as a chronic disease that is passed on from generation to generation. But is it as hereditary as we once believed?

According to a 2014 University of Chicago Medical Center research study, the likelihood of passing on asthma to a future generation may have been overestimated.

Lead author Dr. Carole Ober, chair of the Department of Human Genetics, states: “This could be because those estimates are based on correlations between family members that share environment as well as genes, which could inflate the heritability. Gene-environment interactions are not considered in these large-scale association studies, and we know that these are particularly important in establishing individual risks for asthma.”

According to the research, they identified three gene mutations that increased the risk of developing asthma — GRASP, GSDMB, and MTHFR. These are found in less than five percent of the population, meaning that genetic predisposition is likely in a tiny amount of people. The MTHFR gene mutations were primarily found in people of African descent, while the GRASP and GSDMB were typically found in Latinos.

Although the genetic mutation affects only a small portion of people, the research is extremely positive – Dr. Ober believes that the research can be a template for drug development for more promising pharmaceuticals for the treatment of asthma. As she points out, statins for the treatments of elevated cholesterol originated due to research that discovered genetic mutations in the LDL receptor.

The Allergy Link

With less than five percent of the population testing positive for gene mutations that increase their risk of asthma, what else can significantly increase their risk for asthma?

I found it interesting that from a family of four siblings, all four have asthma — but also, all four of us have allergies of some variety.

About 90 percent of children who have asthma also have allergies of some variety. This is also true for 50 percent of adults.

For this reason, there is a specific diagnosis of asthma, termed allergic asthma, for people who have asthma related to allergies.

Allergens that are known to cause asthma include pollens, such as those blown from grasses, trees, and weeds, animal dander, dust mites and mold spores. Airway irritants may also cause an asthma attack, such as cigarette smoke, dust, strong fumes, cold air and air pollution.

Formula Feeding Infants

As we all know, formula feeding versus breastfeeding is a hot-button issue these days. I was a formula fed baby. As a new mother, I chose to breastfeed – then had to formula feed my son at three months due to supply issues. So reading the research can be upsetting.

The American Academy of Pediatrics (AAP), the American Medical Association (AMA), and the World Health Organization (WHO) all recommend breastfeeding. Breastfeeding is recommended by most of these organizations exclusively for the first six months, then encouraged until twelve months. Why? According to Kids Health, “Breastfeeding helps defend against infections, prevent allergies, and protect against a number of chronic conditions.”

The American Academy of Allergy, Asthma & Immunology (AAAAI) also advocate for breastfeeding. They state that breast milk, “…least likely to trigger an allergic reaction, it is easy to digest, and it strengthens the infant’s immune system. Especially recommended for the first four to six months, it may possibly reduce early eczema, wheezing and cow’s milk allergy.”

That being said, all of these organizations as mentioned earlier (thankfully!) that not all women are capable of breastfeeding, for a myriad of reasons. All agree that in these instances, formula feeding is a healthy alternative. The AAAAI also state that hydrolyzed infant formulas can decrease the risk of food allergy, and subsequently the risk of developing asthma.

Unfortunately, infants that do receive a formula that they are allergic to (such as a formula containing soy or dairy) can have a reaction. A reaction, as discussed above, can subsequently cause asthma.

This is one of those situations where a mother must weigh the pros and cons – and in most cases, a child’s need to be fed outweighs the possibility of developing asthma later on. If the infant is at a very high risk of developing asthma, this should be discussed with the physician, and hydrolyzed infant formula is then an option.

Next page: How to prevent asthma from occurring.

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