'While you wait' test shows which patients will react badly to drugs

Genetics tests for inherited side-effects to some of the most common drugs will be available in high street pharmacies within a year, a conference was told yesterday.

Each test would take no more than 30 minutes and could be run while patients waited for their prescriptions, the British Association for the Advancement of Science's annual meeting at Leicester University heard. The test is designed to identify the small proportion of people who suffer acute reactions to drugs, but can also be adapted to test for strains of infections such as food poisoning or influenza.

Paul Debenham, a geneticist at LGC, an analytical company known as the Laboratory of the Government Chemist until it was privatised in 1996, said the age of "personalised medicine", which exploited the understanding of the human genome, had arrived. "The doctor or pharmacist will be able to check your metabolic status for certain key genes while you're reading a newspaper in the pharmacy or surgery so that he can adapt your medicine rather than wait for you to have the adverse reaction and change it afterwards," Dr Debenham said.

Small DNA differences between people, known as single nucleotide polymorphisms (SNPs), largely account for why some people react badly to a drug. Dr Debenham said he was one of the 7 per cent of the population deficient in the activity of an enzyme in the liver produced by a gene that is involved in metabolising about 100 of the most common prescription drugs -- about a quarter of the total drugs sold today.

The idea is for a biochemical test for the SNPs behind this gene deficiency and other genetic "faults" to be built into a shoebox-sized instrument costing about £4,000, which pharmacists or surgeries could use.

One possibility is for the kit to test for the presence of mutations in a gene that confer an inherited predisposition to deep vein thrombosis. This could be used at airports, Dr Debenham said.

The Human Genetics Commission -- a government watchdog -- has criticised companies for offering home-test kits for gene defects but Dr Debenham said this concern did not include the kit he was developing. "This is not DIY genetics. We're not putting into the hands of individual the ability to do the test themselves."

The machine uses a sample of saliva, blood or urine.