We have known for some time that differences in our genes affect our susceptibility to certain diseases. We now know that differences in some genes can affect the way we respond to medicines – whether we respond well, or whether we are susceptible to the side effects that can sometimes happen with medicine treatment. Pharmacogenomics is the study of the gene differences and the affect of these gene differences on how the genes work, that affect the way we respond to medicines, and the application of that knowledge to develop and use medicines in a more effective way.