One clear bag of fluid

In September 2001, one-year-old Rhys Evans became the poster child for gene transfer. The Welsh boy had been diagnosed with X-linked Severe Combined Immune Deficiency (X-SCID) after months of infections, oxygen tents, intensive care, and finally, an isolation room. His parents – one a teacher, the other a pipe fitter – were offered two options by his caregivers at the Great Ormond Street Hospital in London: bone-marrow transplantation plus a brutal regime of chemotherapy (to allow the new tissue to “take”), or an experimental procedure – gene transfer – that had shown success in two infants at Paris's Necker Hospital. Fearing the potentially lethal consequences of chemotherapy, the parents elected for gene transfer, and in July Evans received what his mother recorded in her diary as “one clear bag of fluid.”.Within weeks, immunological parameters began normalizing, and as Rhys approached his second birthday he was discharged from the hospital. Today, Evans leads a normal life – aside from occasional public appearances for charity, and lots of medical monitoring.

The latter has proven especially important in Evans's case because, across the English Channel, several of his X-SCID peers who underwent the same procedure were not as fortunate. Under the leadership of immunologists Alain Fischer and Marina Cavazzana-Calvo, several children had been cured in a protocol initiated in 1998. But by the early summer of 2002, the French team detected a never-before observed lymphoproliferative disorder in one of their patients. By December, a second patient began showing identical indications. Two years later, a third patient developed the disorder.