Imagine you are a patient. Your doctor diagnoses you as suffering from high blood pressure. You feel that you need drug treatment to control your blood pressure (BP). If you peruse the British National Formulary, the reference manual listing all drugs available in the UK, you will see that he can choose from over 50 drugs. Which would be best for you? Is it like picking random numbers out of a hat? The choice of the drug will be dictated by your age, gender, race, whether you have any other diseases such as diabetes, your kidney function, and whether you are taking any other drugs.

Therefore, there is some degree of personalisation to the medication you may be prescribed. This personalised approach is, however, limited:

• The same starting dose of the same drug may not have the same effect (if any) in all patients.
• There is no guarantee that the first drug will lower your BP. The use of an alternative second drug is also not guaranteed to lower your BP.
• Worse still, you may suffer a side effect from the drug prescribed. Such side effects are usually mild but occasionally can be severe enough to warrant hospital admission.

The question is how can we improve the ability of doctors to more accurately determine the drug and dose in order to maximise its effect and minimise its side effects? One answer is the fast-evolving field of “Pharmacogenetics”.

What is Pharmacogenetics?

Pharmacogenetics can be defined as “the study of the genetic basis for the difference between individuals in response to drugs”.
Though first termed in 1959 by German, Friedrich Vogel, pharmacogenetics, has recently been the source of renewed interest following the completion of the human genome project. We now have a vast amount of information on the building blocks of life, our DNA and the genes encoded within it.

In all human beings, 99.9% of our DNA is identical. The other 0.1% accounts for our observed variability: skin colour, eye colour, gender, etc. Our difference in drug response is one of many other variables found within this 0.1% of our DNA. Pharmacogenetics aims to identify the specific differences which cause individuals to respond to drugs differently.

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