The FDA has approved the first laboratory test system that allows practitioners to consider patients' unique genetic information in selecting medications and doses of medications for a wide variety of common conditions such as heart disease, cancer, and psychiatric diseases. The new test allows health-care providers access to information that could potentially prevent harmful drug interactions.

The new test, the AmpliChip Cytochrome P450 Genotyping Test, is the product of Roche Molecular Systems (Pleasanton, Calif.). The AmpliChip was approved for use with the Affymetrix GeneChip Microarray Instrumentation System manufactured by Affymetrix (Santa Clara, Calif.).

The test uses DNA extracted from blood to sequence a patient's DNA and matches it to the sequence of the probe molecule to which the DNA is most similar.

The AmpliChip test analyzes the cytochrome P450 2D6 gene from the cytochrome P450 family of genes to see if an individual metabolizes certain drugs more quickly or more slowly than average-or not at all. The test is not meant to be a stand-alone tool to determine optimum drug dosage, but should be used with clinical evaluation and other methods of determining the best treatment options for patients.