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Excerpts from: Genetic test tells which smokers become addicted

                                 By Roger Dobson [10/24/00]  More at: Pharmacogenetics (vol 10, p 483)

                                 Scientists have discovered that genes determine how many
                                 cigarettes people smoke each day, and who will become
                                 addicted.

                                 A new genetic test for tobacco addiction based on the work by
                                 the British researchers could now revolutionise the success
                                 rate for anti-smoking therapies. Those who want to give up
                                 would be able to choose a treatment that would work for them.
                                 Instead of trying different drugs, patches and other therapies,
                                 doctors could use a smoker's DNA to match him or her with
                                 the treatment likely to be most successful.

                                 "We have shown that genetic variation in enzymes which
                                 metabolise dopamine in the brain are important in
                                 determining the amount of tobacco that smokers consume. It
                                 is the first study to demonstrate this link."

                                 The team has found that people with different genetic
                                 mutations of the enzymes smoke a different number of
                                 cigarettes a day. It has also found different genetic
                                 mechanisms at work in men and women smokers. The
                                 researchers believe heavy smokers have genetic variations
                                 that reduce natural dopamine activity. The individual is
                                 addicted to smoking heavily because nicotine from the
                                 cigarettes restores the brain's dopamine levels to normal.

                                 The team reckons about 20 genes may be involved in the
                                 smoking process, half dealing with the nicotine
                                 metabolisation, the other with dopamine. "Our new data will
                                 show we can predict whether people will stop smoking using a
                                 nicotine patch," says Dr Walton. "The patch is the best way to
                                 give up smoking but the success rate is only 20 per cent.

                                 "The test is designed to predict which people will benefit from
                                 the different therapies. People who metabolise nicotine
                                 quickly may respond best to a nicotine patch. Those who
                                 met-abolise nicotine very rapidly may need a higher
                                 replacement dose than slow metabolisers." Others may
                                 respond better to dopamine therapyinvolving buproprion, or to
                                 behaviour therapy. "Using genotyping to target the most
                                 appropriate treatment for the smoker could lead to more
                                 effective treatment for tobacco addiction."