A seven-year-old boy from Wales has become the second person in the world to be declared cured of a life-threatening genetic defect that destroyed his immune system.

Rhys Harris was 3 when doctors diagnosed the condition, known as Nemo, which left his body unable to fight infection. He was suffering from incurable tuberculosis when doctors decided that his only hope of survival was an entirely new immune system. They warned his parents, Kevin and Dawn, that he had barely a 30 per cent chance of survival.

After a worldwide search for a bone marrow donor found a suitable match in the United States, his own marrow had to be killed with chemotherapy.

After the transplant, at Newcastle General Hospital, Rhys spent two months in isolation in a transparent plastic bubble. Eight months later he is looking forward to returning home to Newbridge in South Wales.

Rhys is one of only about 40 people to have been given a diagnosis of Nemo since it was identified by doctors in France seven years ago. Nemo is a human protein known as nuclear factor kappa B essential modulator, which leaves sufferers vulnerable to any infection. Only two other Nemo patients in the world have had the operation, one of whom died.

Rhys’s parents gave the go-ahead after being told that he had TB. Mr Harris said: “He went into hospital and we were informed it was terminal. It was just a question of when, not if, his body would collapse from the effects of the TB.”

During the first stage of treatment for the transplant, Rhys’s hair fell out and he had to stay in strict isolation. His parents could not touch him: a single microbe could have led to his death. To see their son, they had to be scrubbed for 20 minutes and wear surgical masks and robes.

Rhys had been left severely deaf by meningitis that he caught at 9 months. Mr Harris, 44, added: “In a way, it is not a bad thing that we couldn’t tell him what was going on. He is blissfully unaware.

“For a whole month we weren’t allowed to kiss him or give him a cuddle. It was unbelievably hard not to be able to hug your child, but we just had to cope and get on with things.”

As his new immune system grew stronger, Rhys was able to remove his mask and move to a bigger room. This week the family received the news they had been wishing for – that tests found no trace of the faulty gene in his new immune system. The family, who had been living in Newcastle upon Tyne to be near Rhys, are hoping to move back to Wales next month.

Mario Abinun, consultant paediatric immunologist at Newcastle General Hospital, said: “He’s doing really well. The transplant went very well and Rhys is now free of Nemo, so we are all delighted.

“This is the first time this operation has been carried out on a child with Nemo in the UK. When Rhys came in he was a very sick boy, but now he is so much better.”

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