What Causes Asthma?

  • Medical Author:
    Alan Szeftel, MD

    Dr. Szeftel received his Medical Degree from the University of Cape Town Medical School in South Africa. His clinical training was at Groote Schuur Hospital. He completed his Internal Medicine residency at Brigham & Women's Hospital and Harvard University. He is board certified in Internal Medicine, Pulmonary Diseases, Critical Care and Allergy and Immunology.

  • Medical Editor: William C. Shiel Jr., MD, FACP, FACR
    William C. Shiel Jr., MD, FACP, FACR

    William C. Shiel Jr., MD, FACP, FACR

    Dr. Shiel received a Bachelor of Science degree with honors from the University of Notre Dame. There he was involved in research in radiation biology and received the Huisking Scholarship. After graduating from St. Louis University School of Medicine, he completed his Internal Medicine residency and Rheumatology fellowship at the University of California, Irvine. He is board-certified in Internal Medicine and Rheumatology.

Asthma Attack Treatment

What are the risk factors for asthma?

One of the more frequent questions my patients ask me concerns the relative risk of their child developing allergies or asthma. In previous Doctors' Views, I have raised issues relating the environment to the development of allergies or asthma. However, both a genetic predisposition and environmental/lifestyle factors are necessary for these conditions to develop.

Is asthma on the rise?

The incidence of asthma has risen dramatically in the past 20 years, a period too short to reflect any significant changes in the gene pool. This supports the important role that environmental influences (allergy, infection, lifestyle, and diet) have on the development of asthma.

What role then does genetics (heredity) play in asthma?

A genetic link in asthma has long been suspected primarily due to "clustering" of cases within families and in identical twins. This does not prove a genetic cause, since it may also reflect shared environmental exposures. Several studies conclude that heredity increases your chances of developing asthma, particularly if allergies or other allergic conditions are present. Moreover, you may pass this tendency to asthma to the next generation. So, what are the chances that your child will develop asthma?

  • 6.5% of families in which NEITHER parent has asthma have a child with asthma.
  • 28% of families in which ONE parent has asthma have a child with asthma.
  • 63% of families in which BOTH parents have asthma have at least one child with asthma.

In other words, when compared with children whose parents do not have asthma, children with one parent who has asthma are three to six times more likely to develop the condition, and children with two parents with asthma are 10 times more at risk. Certainly, identical twins are more likely to share allergies and asthma than are nonidentical (fraternal) twins. Asthma may skip a generation or surface in other branches of your family. Inheriting the asthma gene does not necessarily mean that you will definitely develop asthma.

The genetic material that you were born with, the amount of environmental asthma-promoting factors in your environment, and your lifestyle can all conspire to put you more or less at risk for developing asthma. As such, your genetic makeup is only one piece of the puzzle.

Medically reviewed by Margaret Walsh, MD; American Board of Pediatrics


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Reviewed on 2/9/2017

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