There have been several success stories in the field of pharmacogenetics in 
recent years, including the analysis of HER2 amplification for trastuzumab 
selection in breast cancer and VKORC1 genotyping for warfarin dosing in 
thrombosis. Encouraging results from these studies suggest that genetic factors 
may indeed be important determinants of drug response and toxicity for at least 
some drugs. However, to apply pharmacogenetics appropriately, a thorough 
understanding of the scope and limitations of this field is required. The 
challenges include an appreciation of biological variability, logistical issues 
pertaining to the proper management of information, the need for robust methods 
and adequate sample quality with well-designed workflows. At the same time, the 
economics of pharmacogenetic testing from the perspective of clinicians, 
patients, governments, insurance companies and pharmaceutical companies will 
play an important role in determining its future use. Ethical considerations 
such as informed consent and patient privacy, as well as the role of regulatory 
bodies in addressing these issues, must be fully understood. Only once these 
issues are properly dealt with can the full benefits of pharmacogenetics begin 
to be realised.