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.
Pharmacogenetics, by definition, refers to the study of genetic differences in metabolic pathways which can affect an individual’s responses to drugs in terms of both therapeutic and adverse effects. In recent years, there have been several success stories such as HER2 for trastuzumab in breast cancer and VKORC1/CYP2C9 for warfarin in thrombosis. Encouraging results from these studies suggest that genetic factors may indeed be the major determinants of drug response for at least some drugs. This presents the possibility of personalising treatments in the near future to better suit individual patients. By stratifying patients according to their genetic profile, the aim is to identify those that will benefit from available treatments in terms of maximum response and minimal toxicity. However, as with ‘conventional’ disease-genetic testing, a high level of expertise is required to perform these tests and to interpret the results correctly. Thus, it is important to be aware of the numerous pitfalls regarding biological agents, logistics and ethical issues that must be overcome before the benefits of personalised medicine can be realised. In addition to the scientific aspects, the economic challenges associated with the introduction of pharmacogenetic tests should also be considered.
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