What are the obstacles to the widespread use of pharmacogenetics?

Pharmacogenetics has many potential benefits, and great advances are being made in human genetic research. This has tempted some enthusiastic supporters to predict a new era of healthcare - personalised medicines.

In reality, there are many hurdles to overcome before we are all being regularly given treatment based on our genes, and the introduction of pharmacogenetics is likely to be slow and gradual.

Some of the many challenges are:

• It is difficult to link a genetic variant unambiguously with a particular drug response.
• An association between a particular genetic variant and a response to a drug in one population may not be present in another; a test may be useful in one location but not another.
• There are often a large number interacting genetic and environmental factors may that cause the variation in response to a drug.
• Even when associations between a genetic variant and a drug response have been clearly demonstrated, suitable tests still have to be developed and proved to be effective in clinical trials.
• A test has succeeded in a clinical trial still has to be shown to be useful in a healthcare setting and its economic consequences studied.
• Regulatory agencies will have to consider how they assess and license pharmacogenetic products.
• Health services will have to adjust to cope with new ways of doing things.
• The behaviour of individual doctors will need to change.

The abacavir example shows that the pace of change can be quick in some cases. In most cases, however, the implementation of pharmacogenetics is likely to be a complicated process.