The lives of six boys with a deadly genetic disease have been transformed by a pioneering treatment to correct errors in their DNA, say doctors. A defective immune system in Wiskott-Aldrich syndrome leaves people vulnerable to infections and bleeding.

A British and French study, published in JAMA, used tamed HIV to correct the defects.

One child who needed a wheelchair can now move freely, while symptoms have improved in the other patients. The syndrome affects up to 10 children in every million born and almost exclusively affects boys. Even tiny bumps and scrapes can lead to wounds that are slow to close in patients. Eczema is common, they face repeat infections including pneumonia as well as some cancers and autoimmune diseases.

It all stems from an error in the genetic code that contains the building instructions for a key element in the immune system – a protein called WAS. The main treatment is a bone marrow transplant – but that is an option only when the donor is a close tissue match, such as a sibling.

The trial at Great Ormond Street Hospital, in London, and Necker Children’s Hospital, in France, removed part of the children’s bone marrow. It was purified in the laboratory to find the cells that regenerate the immune system and a tamed version of HIV was used to “infect” the cells with the correct DNA. The corrected bone marrow cells were then put back into the children. In six out of seven boys, the therapy was a success. It reversed symptoms and massively cut the number of nights spent in hospital. One French child with severe autoimmune disease no longer needs a wheelchair.

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