Doctors at a hospital in the North of England say that a seven-month-old baby in their care has made a dramatic recovery, following a bone marrow transplant, from a usually fatal combination of diseases. The boy, who has a rare genetic disorder affecting the immune system, was thought to have a tiny chance of surviving after he developed a severe lung infection and cancer. Graham Easton of BBC Science reports:

Doctors at Newcastle General Hospital in the north of England gave the baby - called Tom - a million-to-one chance of survival after he developed a severe lung infection and cancer of the skin, bone, liver and spleen. Tom has a rare condition called Severe Combined Immunodeficiency which renders his immune defences against such diseases virtually useless, and means he has to live within a strictly sterile environment.

Doctors were afraid that his chances of surviving conventional anti-cancer treatment were close to zero. So instead, they opted to help him fight the cancer by replacing his defective immune system with a new healthy one - via a bone marrow transplant.

Even that was something of a gamble - but it seems to have paid off. Ten weeks on from the transplant, doctors say Tom now has no sign of cancer, no infection, and a fully functional immune system.

He's now been allowed out of his sterile "bubble" in time to spend Christmas with his parents. About 40 babies in Britain are diagnosed with Severe Combined Immunodeficiency every year.