Targeting medication to people who are genetically susceptible to a disease but do not yet show the symptoms of it can be a questionable measure. In large populations, there is concern that likely most of the people taking preventative medications would never have developed the disease anyway.
Targeting medicine specifically to those genetically prone to a condition without evident symptoms might be dubious. In sizable groups, it raises concern that many individuals on preventative drugs would likely not have contracted the disease at all.