Child leukaemia starts in the womb

Most cases of childhood leukaemia start in the womb and are caused by a genetic defect that is not inherited, scientists have discovered.

Most cases of childhood leukaemia start in the womb and are caused by a genetic defect that is not inherited, scientists have discovered.

The study of children aged two to five, suffering from the most common form of leukaemia in young people, found that those who develop it have an altered or mutated gene that arises before birth, during the development of blood cells in the foetus. The findings cast new light on the cause of childhood leukaemia, the subject of much speculation. Radiation, chemical pollution and infection have all been blamed for the illness, which affects one in 2,000 children in Britain.

The most common form, acute lymphoblastic leukaemia (ALL), accounts for 80 per cent of all cases and is diagnosed in about 400 children each year. Although most survive it with the help of drugs, some undergo bone marrow transplants, and the results can be fatal.

Scientists from the Institute of Cancer Research, who published the research in The Lancet , the medical journal, carried out blood tests on nine children and a pair of identical twins. The researchers found that the leukaemia cells taken from the children with ALL, had an altered or mutated gene.

Using highly sensitive molecular probes the researchers were able to trace back the appearance of this mutation and detect its presence in blood spot tests, routinely taken in the first month of babies' lives.

Previous research, conducted by the same team, has shown only 5 per cent of twins both develop the illness, so the researchers concluded that the mutation alone was not enough to lead to full-blown leukaemia and that some post-natal event or exposure was also necessary.

Professor Mel Greaves, from the Leukaemia Research Fund Centre at the Institute of Cancer Research in London, coauthor of the research, said: "It is the first direct evidence that the common form of leukaemia in children originates in the womb and could lead to its origins being solved in the next few years. The puzzle of childhood cancer is unfolding."

Dr Peter Rigby, chief executive of the Institute of Cancer Research, said: "We are making real progress and this new knowledge takes us further towards a complete understanding [of leukaemia]."