One of the first children in Britain to receive gene therapy for an immune system disorder has developed leukaemia as a result of his treatment.
The boy, aged 3, is the first gene therapy patient in Britain to fall ill with leukaemia, a known risk of the procedure. A similar programme in France has caused four cases of the blood cancer, and one death.
The child, who has not been named, was born with X-linked severe combined immunodeficiency (X-SCID), a genetic condition in which the immune system fails to develop. It is often called "bubble baby syndrome", because sufferers are shielded in a sterile pouch. Without treatment, they die in their first year, from infections such as pneumonia or chicken pox.
Two years ago the boy became the eighth patient to be treated in London on Great Ormond Street Hospital's gene therapy programme, which uses a genetically modified virus to correct the faulty DNA that causes X-SCID.
While his immune system responded "extremely well" to the procedure, leukaemia was diagnosed last month, the hospital said. This is an acknowledged risk...