A family whose son spent his part of his early life in a protective bubble are celebrating after he was given the all-clear.
Christopher has spent months in an isolation unit
The parents of two-year-old Christopher Reid also learned their unborn daughter will not suffer the same condition.
Christopher was born with the rare inherited condition x-SCID, which prevented his immune system developing and left him vulnerable to infection.
The blond youngster was forced to spend several months in an isolation unit in hospital where he had a protective bubble around his head.
He was banned from playing with other children until a pioneering operation at Great Ormond Street Hospital in London.
He became only the second child in the country to receive gene therapy to tackle x-SCID - Severe Combined Immuno-Deficiency.
Christopher, of Oakwood in Derby, now enjoys trips to the supermarket with his mother Rachel, 32, father Stephen, 28, a policeman, and brother Sam, 11.
He was diagnosed with the x-chromosome disorder, which affects about 100 boys in the UK, in October 2001 at the age of eight months.
His risk of infection was so great that he was instantly barred from seeing other youngsters and even family members had to be vetted before visiting.
An operation in December 2001 introduced an artificially created gene - mixed with his bone marrow - into the boy's body to correct the problem.
Blood samples taken on Wednesday revealed that his immune system is now working perfectly.
His mother said: "He has changed from an unsettled, shy and miserable baby into a confident and happy toddler with a wonderful sense of humour.
Doctors had worried following the 2001 operation, as Christopher's body did not respond as quickly to treatment as Rhys Evans - the first child to have had gene therapy.
"The gene therapy has now restored much of his immune system, he takes protective drugs but can visit soft play areas and mother and toddler groups," a Great Ormond Street spokesman said.
"His development has been rapid in recent months and the family managed two weeks in France in June - a real contrast from months spent isolated in different hospitals round the country."
They have also been able to confirm to the family that the disease will not affect their unborn daughter, as girls can only became carriers for the disorder.