Published on Jan 28, 2013 with 0 comment
All practicing allergists are frequently asked by parents the chance or likelihood of a child being born with allergies or asthma if one or both parents are allergic. At best, the genetics of allergic disease is an inexact science, and the predictions vary widely. I have always given the standard answer: If one parent is allergic or asthmatic, each child has approximately a 25% chance of having allergies or asthma, and if both parents are allergic or asthmatic, the chance increases to approximately 50%, or slightly higher.
Until new data emerged recently from The Journal of Allergy and Clinical Immunology, I thought my response was adequate. But, recent data suggests a very strong “parent-of-origin effect” as an important variable. A total of 1456 children were retrospectively examined for the presence of asthma and eczema and were followed until age 18. Without getting into the complicated statistics involved, the researchers came to the following startling conclusions: Maternal asthma was associated with asthma in girls, but not in boys. Conversely, paternal asthma was associated with asthma in their sons, but not in their daughters. Maternal eczema increased the risk of eczema in girls, and paternal eczema increased the risk for eczema only in their boys. Who ever would have guessed it?
In my opinion, a much larger study needs to be done to confirm these finding and better clarify the genetics of allergic disease. Until then, it is certainly going to make for some interesting discussions.