What is the term for a strong response to a harmless antigen in the environment

An allergy

An allergy is a disorder caused by an abnormal reaction to a harmless antigen in the environment. These diseases include food allergies, hay fever, atopic dermatitis and allergic asthma. Symptoms may include, a runny nose, shortness of breath, swelling red eyes, or sneezing. Non-allergic individuals tolerate allergens without problems. The two main types of allergic reactions are immediate hypersensitivity and delayed hypersensitivity.

"1. it should be, it has been for about 20 years, and it's really not much different in the end than breeding animals to have particular traits. there are always concerns about genetically engineered animals/plants affecting the environment in unexpected negative ways, but i can't think of an example where the fears didn't turn out to be baseless.  

first, as you point out, it would be a great advance in pharmacology, to be able to tailor drugs and their doses to me. the pros involve better medical treatment. the cons involve privacy issues like insurance companies denying coverage to people with genetic risk factors. looking at dna markers wouldn't affect the frequency of genetic diseases, but it would allow detection of them earlier. and ok, actually i suppose that if people used this information to avoid having children with genetic diseases, some might decrease in frequency."