A pharmacogenetic ‘gene chip’ test kit produced by Swiss pharmaceutical firm Roche has received approval from the Food and Drug administration (FDA) for use in the US along with the Affymetrix GeneChip Microarray Instrumentation System (see press release). The AmpliChip Cytochrome P450 was launched in 2003 by Swiss pharmaceutical firm Roche Diagnostics, but withdrawn from sale in the US in November 2003 due to regulatory issues. The test became the first DNA microarray based test to receive EU approval in September 2004 (see newsletter item). The device detects common polymorphisms in the CYP2C19 and CYP2D6 genes, which encode two key enzymes involved in the metabolism of many sorts of drugs including common anti-depressants, painkillers and beta-blockers. Certain common variants of these genes affect the rate at which drugs are metabolized by an individual and hence the response to the drugs. On the basis of the AmpliChip CYP450 results, individuals are classified as poor, intermediate, extensive, or ultra-rapid drug metabolisers, allowing doctors to select the most appropriate drug and dose for the patient’s genotype with respect to drug metabolism. The FDA approval paves the way for the marketing of similar microarray-based genetic tests in the US.