Girl trapped in an indoors 'bubble' saved by sister's bone marrow transplant #CarryGobySeanKellz #FutureGroupNG via @i_amreginaldjr

A GIRL who has lived in a “bubble” because of a rare immune disorder can play outside for the first time after a life-saving transplant from her sister.

Sisters Milly, left, and Kacey can now play happily in their garden in Hampshire [SWNS]

Six-year-old Milly Smith was born with a disease suffered by one in eight million girls which left her with no immune system, meaning just going outdoors could be fatal.

Then a routine test to check that eight-year-old sister Kacey did not have the same condition revealed she was a perfect bone marrow match for Milly.

Kacey immediately agreed to donate her “magic” and Milly perked up within days of the operation at London’s Great Ormond Street Hospital.

The transplant has been 98 per cent accepted by her little sister, giving her a brand new immune system – and the pair can play outside for the first time in years.

Kacey, who previously had to miss parties and playing out in case she brought back bugs, said: “I feel proud of what I did.

“Before we were all quite sad and I missed out on a lot of things because Milly couldn’t do anything.

“Now she is much happier and we can play out the front, we can go to McDonald’s and we are going on holiday. We couldn’t do any of that before.”

My sister was nice and kind to help me. I can’t remember how I felt before but now I feel all right

Milly Smith

Milly, who goes back to school after Easter, said: “My sister was nice and kind to help me. I can’t remember how I felt before but now I feel all right.”

Parents Theresa and John, both 39, of New Milton, Hampshire, realised “something wasn’t right” soon after Milly was born.

She was constantly in hospital with various illnesses, almost losing her battle with a chest infection at 16 months.

But it was not until she was four and a toenail infection landed her in hospital and took nine courses of antibiotics to clear that more tests were done.

Milly was diagnosed with chronic granulomatous disease, where the immune system cannot fight infections.

Spores from grass or leaves could have triggered a fatal chest infection, while a cut could have caused blood poisoning.

Milly’s parents had to pull her out of school to keep her away from other children. Theresa said: “She’d no defence against anything. We went through hell.

“Now we are doing all the things people just take for granted. Milly went to her first birthday party last month and we have booked a family holiday to Spain for June.

“We still have to be careful but the girls can go out to play and we have lots to look forward to.”