ALEX Herbert finishes his meal of fishfingers and announces he's still hungry.

One chocolate biscuit later and the four-year-old pads off to the lounge and expertly loads a Disney cartoon into the video.

Fast-forwarding the adverts, he promptly ignores the screen and settles down instead to play with his toy trucks.

It may be a familiar scenario to many, but for parents Ian and Alyson it is a state of normality they could hardly have dared wish for.

Just six weeks after undergoing a bone marrow transplant - the only cure for a rare genetic disorder which claimed the life of his seven-year-old brother - Alex is home.

During his time in Newcastle General Hospital's Bubble Unit, Alex was determined to endure the pain and discomfort as bravely as seven-year-old Edward had done before him.

Free from the wires and tubes and protective room, he wanders the house enjoying his new-found freedom.

"As far as transplants go, it was straightforward, without a lot of complications. I was really hoping we wouldn't be in hospital over Christmas," said Mrs Herbert, 36.

"It is still difficult because we haven't got Edward - but we are home again and we can start to have a family life at long last."

Their ordeal began in April last year when Edward caught a virus which affected his bone marrow. It was later diagnosed as XLP, which attacks the immune system, turning the most minor infection into a deadly threat.

Since then, the couple, who live on the family farm near Barnard Castle, County Durham, have alternated their bedside vigils first with Edward, then, three months after his death, with Alex.

Mr Herbert, 37, provided two bone marrow transplants for Edward, who also received almost weekly blood transfusions. Sadly, he developed a number of complications and died in June.

Alex, born with the same disorder, received a bone marrow transplant from eldest brother Michael, nine, who is free from XLP. It proved a perfect match.

He suffered a few side effects from the chemotherapy but will continue medication for up to two years.

The only other tell-tale signs of his ordeal are hair loss and the line used to deliver blood transfusions and drugs into his chest.

Alex is subject to a number of rigorous precautions at home to cut the risk of infection, including having to wait a further three months to join his friends at Barnard Castle Primary School.

The couple are keen to express their gratitude to hospital staff and the many people who have donated to the Bubble Appeal - which funds medical equipment, parental support and research for the bubble unit. So far, at least £6,000 has been raised in the Teesdale area.

They have witnessed first hand how vital the unit - one of just two in the country dealing in immunology transplants - is for so many desperately ill youngsters.

For now, Alex is overjoyed to be back with his family, revealing he is "more excited than Christmas".

Mr Herbert said: "People might think that because Alex is out of hospital he's better, but it is a long process. His immune system is still very low but we can breathe a sigh of relief because he's home."