By Catherine Marston BBC News correspondent

A seven-year-old Irish girl has saved the lives of her three younger brothers by giving them some of her bone marrow.

Ciara MacMahon, from Limerick, endured two painful operations to help cure the boys of a rare genetic illness.

I had a lot of misgivings about people saying we were lucky Ben MacMahon

John, who is four, and two-year-old twins Edward and Rory, were born with the life-threatening condition Chronic Granulotis disease.

The symptoms, only seen in boys, means they had no resistance to bacteria or mould.

Ciara, who was not a carrier of the illness, was a perfect bone marrow match for her brothers.

Agonising decision

But for her parents Ben and Geraldine MacMahon it was a tough decision to ask their daughter to go through such a painful procedure.

They also knew she would have to endure two separate operations to collect enough bone marrow for all three boys.

Mr MacMahon said: "I felt that because of her age that we were almost taking advantage of her.

I think it very unlikely that any of the boys would have survived childhood Dr Andrew Gant

"I had a lot of misgivings about people saying we were lucky.

"I didn't feel very lucky".

His wife said: "I know she was very anxious about it and very frightened.

"I think she was relieved when the first donation was over and she was fine for a few months."

The operations took place at a specialist bone marrow transplant unit in Newcastle upon Tyne.

No specialist

Dr Andrew Gant said it was almost certain the three boys would have died without Ciara's help.

He said by the time the boys got to nursery school age they would have probably increasingly suffered from infections - one of which could have proved fatal.

"I think it very unlikely that any of the boys would have survived childhood," he said.

But the operations meant an upheaval for the family, who had to temporarily move to England since the treatment is unavailable in Ireland where there is no paediatric immunologist.

So Mr MacMahon had to give up his job with the Meteorological Office and the family left their farm and business behind.

Each day they have had to travel from their temporary home in Wylam, in Northumberland, to visit the children in the unit.

Children recovering

All three boys are now out of hospital but still have to take dozens of different medicines each day to ensure the transplant is a success.

But they should now make complete recoveries.

And the family hope they might finally get back to Ireland at Easter time.

But they are still desperate for a specialist consultant to be appointed in Ireland so the boys can be monitored at home so that they will not have to travel to and from Newcastle.

Meanwhile Ciara is well following her operations.

Her parents say one day they will explain to the boys that their big sister saved their lives.