Modified blood cells lock together to block the flow of blood around the body. This can cause intense pain, organ damage and can be fatal. The teenager who received the treatment had so much internal damage he needed to have his spleen removed and his hips replaced. He had to monthly go into hospital to have a blood transfusion to dilute his defective blood. Doctors at the Necker Children’s Hospital in Paris removed his bone marrow where the blood cells are produced, genetically altered it in a lab to compensate for the defect in his DNA and after reintroduced it in the patient’s body. After, the teenager has been making normal blood so the intervention was a success. For the instant this is a medical research but the hope to use it at a treatment method in all the cases exists. “I think it’s very significant, essential they’ve given him his life back,” said Dr Deborah Gill from the gene medicine research group at the University of Oxford.