Why Do Only Some People Have Allergies?
Some people are more likely to develop allergies than others because of a genetic state of hyper responsiveness to allergens, referred to as atopy.
This concept is supported by the fact that children of parents with allergies have dramatically increased risk of developing allergies themselves. While only 10 percent to 15 percent of children in the general population suffer from allergic conditions, the probability increased to about 50 percent if both parents suffer from allergies. The risk is even greater, exceeding 70 percent, for children of parents who both suffer from an identical type of allergy. Only 13 percent of children of non-atopic parents will develop allergies.
The progressive development of increasingly debilitating allergic disease as an atopic child grows into adulthood has been referred to by some researchers as the “allergy march.” Children with a genetic predisposition toward the development of allergy, i.e., atopic children, often start with sensitivity to foods that exhibits itself as atopic dermatitis during the first two years of life.
After age two, these children often develop sensitivity to inhalant allergens such as pollens or dust mites, producing allergic rhinitis. Clinical studies have shown that children who develop atopic dermatitis, or allergic rhinitis at a young age have an increased tendency to develop asthma, as they grow older.