Breath of Fresh Air: Feature Articles
Chapter 34: Is Asthma Inherited?
The simple answer to this question is, YES, a tendency to develop asthma is inherited. If one of your biologic parents has or had asthma, then you are morely likely to develop asthma than if he or she did not have asthma. If both of your parents have asthma, you are even more likely to develop asthma than if only one parent has this condition.
Another confirmation that asthma is inherited comes from studies of twins. If one identical twin has asthma, the other twin (who shares all the same genetic information as his/her identical twin) is more likely to have asthma than when one of two non-identical twin siblings (who share some but not all of their genes in common) has asthma.
However, the whole story is not as simple as the idea that one either inherits the asthma gene or genes from one's parents or one does not. For one thing, we know from studies of identical twins that if one twin has asthma, the chances of the other twin developing asthma is only 1 in 3, despite the fact that the inherited information in their genes is identical. For another thing, we know that some people working in certain occupations are more likely to develop asthma than if they had not held those jobs. For instance, if you work in a lumber mill and are exposed day after day to sawdust from certain types of woods, you may develop asthma as a result of this exposure. First, workers experience asthma symptoms only when they breathe in the sawdust, but with time they develop asthma to all the usual stimuli (such as exercise, cold air, respiratory tract infections, etc). Sometimes the asthma goes away if the person stops working in the sawmill and sometimes it does not.
Like many other diseases, asthma likely results in part from a tendency, present in one's genes, toward developing the disease and in part from exposures that one encounters in the world around us: that is, part heredity, part environment.
We do not know exactly what in our environment contributes to developing asthma in those with a genetic predisposition. It may involve breathed particles to which we are allergic, cigarette smoke or air pollution, viruses or other germs, or some combination of these and possibly other factors.
Active research, including some being conducted at the Brigham and Women's Hospital, is attempting to identify the specific genes responsible for the inherited tendency toward developing asthma. It is likely that within the next decade we will know at least some of the genetic pieces to the puzzle of what causes asthma.