Gene therapy used to 'cure' rare immune disease

A team of scientists based in Frankfurt, Germany, has become the world's first to treat a rare and 'incurable' hereditary immune disease in adults, using gene therapy. Gene therapy has been used successfully in the past, but this has generally been in the treatment of children. Over the past two years, the team have treated two men - aged 25 and 26 - with the condition, known as chronic granulomatous disease (CGD), at Frankfurt University Hospital.

Chronic granulomatous disease is a rare condition, inherited in genes found on the X chromosome, and so passed on by the mother, where the body cannot kill invading bacteria and fungi. As a consequence, sufferers frequently suffer from infections, often life-threatening. The only treatment currently available is to undergo a bone marrow transplant. The disease - which causes there to be defects in blood cells called phagocytes (a type of infection-fighting white blood cell) - affects only one in 250,000 people in the UK. In most cases, it is caused by a defect on the gp91phox gene that affects the way the bone marrow produces phagocytes.

The scientists, who describe their work in the early online version of the journal Nature Medicine, used  gene therapy to alter the genetic composition of the men's cells to enable their immune systems to better fight bacterial and fungal infections. The team of 27 scientists was able to raise the proportion of healthy immune cells in the men's blood to above 50 per cent, which subsequently lead to a lessening in infection and the men being able to withstand new infections. They took stem cells from the men's blood and altered them in the laboratory so that they contained a healthy version of the defective gp91phox gene, using a new technique that enabed the genes to be inserted into many cells at the same time. The cells were then reintroduced to the men, who had undergone chemotherapy designed to target as many of the defective phagocytes as possible. Sixteen months later, the patients showed signs of a complete recovery - their doctors say that they have gained weight, and are infection-free, for the first time since childhood.

Dorothee von Laer, gene therapy coordinator at the Georg Speyer laboratory in Frankfurt, said that the technique used might also prove suitable for the treatment of other hereditary conditions where people are born with a defective gene. And Manuel Grez, of the Institute for Biomedical Research in Frankfurt, said that the success in this trial may illustrate gene therapy's potential to be used to treat other similar inherited diseases. However, there is some concern that the use of gene therapy in this way could have as yet unknown consequences, such as cancer of the blood - research into this is ongoing.