Pharmacogenomic tests offer a promising strategy to improve the safety and 
efficacy of drug treatment. Compelling examples, such as HLA-B*5701 testing to 
identify patients at risk for abacavir-associated hypersensitivity, are already 
changing clinical care. However, the level of evidence required to establish 
clinical utility is often the subject of debate. Determining the most efficient 
and effective pathway to benefit for a given test is therefore both a practical 
and an ethical concern.