In the Bone Marrow Transplant Unit at Great Ormond Street Hospital, doctors strive to save the lives of children with life-threatening congenital diseases. They must attempt treatments which have very uncertain chances of success and can even threaten the lives of the children they are trying to save.

Great Ormond Street Hospital is the last chance for children in the UK whose lungs are failing because of cystic fibrosis and other conditions. In a few very severe cases each year, their only hope of survival is to undergo a radical and risky step - a double lung transplant.

Great Ormond Street is Britain's leading hospital for treating children with serious diseases of the brain - from tumours to epilepsy to rare neurovascular conditions. To save lives, doctors have no option but to undertake treatments which carry grave risks - children may be left with a mental impairment or may not even survive.