A clinical trial has now begun with more than 10 patients in London to try to introduce genes into cells in the lungs of patients, following the latest successes. In those, two clinical trials - one in Edinburgh and another in Oxford and Cambridge - showed that genes which correct the cause of cystic fibrosis can be delivered to cells in the nose lining by using fatty cells known as liposomes.
"We were looking for safety and the actual transfer of the genes," said Dr Martin Scott, of the Cystic Fibrosis Trust.
"Both studies have shown that this system is safe, and have produced weak signals that the gene instructions are being switched on."
He added that "things are on course, from the cystic fibrosis point of view" towards an eventual cure by gene therapy.
Cystic fibrosis, which causes the body's glands to overproduce mucus, is the most common life-threatening inherited disease in the United Kingdom, affecting one in 2,500 babies. The single gene which causes it was identified in 1989.
The idea of replacing faulty genes with working ones has been held out as a hope for years to sufferers. But nobody was sure genes introduced into body cells would perform the function they were meant to.
The latest studies, published in the journal Gene Therapy, follow years of mixed fortunes for those trying to develop gene therapy cures for cystic fibrosis.
Britain's first gene therapy patient, Carly Todd, received genes intended to correct her cystic fibrosis in 1993. But a year after the operation doctors could find no traces of the new genes. She recently had a bone marrow transplant.
The author of work in Edinburgh, Professor David Porteous, of the MRC Human Genetics Unit and Edinburgh University, said: "There is a long way still to go before we have a cure for cystic fibrosis, but we are moving in the right direction."Reuse content