You know what about DAO?
All my cousins from my father's side have asthma, and my sibs have rhinitis. I don't. But I know there is some inflammation due to allergy going on, and I suspect it is MAO-A related. I also suspect the +/+DAO and +/+MAO-A play a huge role in leaky gut and gut dysbiosis.
In my husband's family, he and his sibs have always had asthma, but when we got married his asthma went away, to come back some 15 years later, stress driven, perhaps from the inflammation promoted by his 2 +/+ COMTs.