Genetic tests can check for conditions

Mr Blair was speaking on Tuesday morning hours before new Health Secretary John Reid was due to unveil a White Paper containing plans for a big expansion in the use of gene therapy and testing in the NHS.

Mr Blair, who hosted a breakfast seminar attended by about 25 genetic experts at Downing Street, said the potential benefits of genetic science were enormous.

He said: "It will make an enormous difference to the way we deliver health care.

We hope that the government addresses the issue of genetic discrimination Dr Helen Wallace My daughter has cystic fibrosis

"I think it will change the whole way we deliver health care in this country."

However, the Prime Minister conceded there were also ethical problems surrounding the use of the technology

Dr Reid is expected to tell the Commons that more money is to be pumped into gene therapy, which is showing great promise as a way to correct genetic disorders.

He is also likely to signal the greater use of genetic testing by the NHS to determine who is at risk of developing problems.

However, Dr Reid is likely to counter-balance this by pledging new safeguards to minimise the risk of discrimination against people whose test results make for bad news.

There is concern that these people will be treated as pariahs by the insurance industry and employers among others

The White Paper is also likely to place restrictions on the sale of over-the-counter testing kits for inherited conditions.

There are concerns that easy availability of these kits could lead to people being given bad news without proper expert back up in the form of counselling.

Healthy copies

Knowing which genes are faulty will help us to target our resources and improve screening. Professor John Burn Gene testing: The pros and cons

Genetic disorders, such as cystic fibrosis, muscular dystrophy and haemophilia, are caused by mutant variations of normal genes which are unable to perform their proper function.

Gene therapy works by implanting healthy copies of these genes, often attached to a harmless virus, into the patient's own cells.

Dr Helen Wallace, of the pressure group GeneWatch UK, said legislation was needed to ensure gene testing was not abused.

She said: "We hope that the government addresses the issue of genetic discrimination by putting legislation in place to prevent a genetic underclass from developing.

"At present a voluntary moratorium is in place, but we would really like to see concrete measures put in place to protect the public."

Dr Wallace also expressed concern that the potential of gene technology had been over hyped.

"We are worried it has been oversold as a way to tackle common complaints such as heart disease, cancer and obesity."

Professor John Burn is medical director of the Institute of Human Genetics at the Centre for Life in Newcastle Upon Tyne and a member of the Human Genetics Commission.

He said: "We know that about a third of the overall cause of common diseases is genetic, and it assumed that knowing which genes are faulty will help us to target our resources and improve screening.

"For instance, my particular interest is bowel cancer. There are perhaps 12,000 people in the UK who carry a gene that predisposes them to bowel cancer.