Three young brothers owe their lives to their older sister after she donated the bone marrow that saved them all.

Ciara MacMahon, seven, has undergone three operations for the sake of John, four, and twins Rory and Edward, two.

Her bravery has been rewarded as Rory, the last of the MacMahon to be treated, has emerged from a sterile "bubble" to begin a healthier life.

All of the brothers suffer from severe combined immune deficiency syndrome (Scids), meaning they were born without immune systems.

It left them so susceptible to infections that even common illnesses such as a cold, or a kiss from their mother, could have been responsible for their deaths.

All three operations were carried out in a specialist unit at Newcastle General Hospital, where the boys are still having follow-up treatment.

For the past ten months, parents Ben and Geraldine watched as their sons took turns in a sterile bubble of air, an environment which became their home.

Mr MacMahon, 36, said: "It is tough on Ciara because she has had to have general anaesthetics.

"The bone marrow was removed, which involved drilling into the pelvis. She is very brave and we're proud of her.

Mr and Mrs MacMahon left their home, jobs and relatives behind in County Limerick, Ireland, in March last year so the children could live in their bubble environment.

"The Irish Government have paid the medical bills, but we have had to fund the trip and expenses for living here ourselves," said Mr MacMahon.

It is also a comfort to the family that Ciara, who is staying with an aunt in Ireland, does not need to travel to the North-East as she has already provided enough bone marrow for her twin brothers.

Dr Andrew Gant, of the Scids unit, said: "I think it very unlikely that any of the boys would have survived childhood."