By Helen Briggs BBC News Online science reporter in Leicester

Going to a high street chemist for an instant genetic test could become a reality in the next year.

Scientists are developing a cheaper, quicker genetic testing system that gives results in half an hour.

It's not DIY genetics

Dr Paul Debenham

A person would be able to find out about their health and genetic profile, by simply providing a saliva sample.

It should be able to diagnose the strain of microbe responsible for an infection or find out whether someone is likely to have an adverse reaction to a prescribed medication.

In the future, the kit might even be able to tell whether someone has a gene that predisposes them to breast cancer or whether they are genetically susceptible to getting a deep vein thrombosis (DVT) on long flights.

On-the-spot diagnosis

Current genetic tests rely on extracting DNA from blood. The sample has to be sent away to a lab and the results take days.

The new system works directly on saliva and can be carried out in a miniature genetics laboratory, the size of a shoe box.

The prototype is being developed by LGC Ltd, formerly the government-owned Laboratory of the Government Chemist, in collaboration with Agile, a London-based start-up company.

According to LGC's Dr Paul Debenham, it should be ready in a few months, with the final version reaching high street chemists or the doctor's surgery in a year or so.

He estimates that the kit will cost about �4,000, bringing it within reach of doctors and pharmacists.

'DIY genetics'

Genetics watchdogs recently aired concerns about some genetic tests on sale in shops or on the internet.

The Human Genetics Commission is considering what restrictions, if any, should be placed on over-the-counter genetic tests.

How it works

Patient gives saliva sample (or blood or urine) Doctor adds it to water in a plastic well and puts it in the machine A miniaturised version of the polymerase chain reaction (PCR) takes place The results appear in a window on the box after 25 minutes It can test for a number of gene mutations and pathogens

But Dr Debenham said the device was aimed at health professionals not consumers.

"It's not DIY genetics", he told reporters at the British Association festival of science at Leicester University. "This is just bringing it closer to the point of care."

One novel use of the kit is to find out whether someone might be more likely to develop a DVT because of their genetic make-up.

It could be used in the airport lounge before a flight to screen for mutations in the gene for the blood clotting abnormality, factor V Leiden, said Dr Debenham.

Factor V Leiden is an inherited blood coagulation disorder that increases the risk of blood clots.