A 12-year-old Salt Lake girl was breathing on her own Friday after receiving part of her mother's lung in the nation's first live-donor lung transplant, a procedure that could help other children with some lung diseases.

Mother and daughter remained in good condition a day after surgeons replaced the daughter's right lung with a lobe removed from the mother's right lung, said Joyce B. Thomas, a spokeswoman for Stanford Medical Center."Both are doing fine," Thomas said.

The mother started breathing on her own shortly after the four-hour procedure Thursday. The patients' names were being withheld at the family's request.

Perhaps hundreds of children a year could benefit from the procedure, which lessens the chances of tissue-rejection by transplanting tissue from a related donor, said Dr. Vaughn Starnes, who heads the heart-lung transplant team at Stan-ford.

Transplants from related, live donors are important for children because they have a higher rate of rejection than adults, which "might have something to do with their more active immune systems," Starnes said.

The most likely benefactors are patients with a large hole in the diaphragm, high blood pressure on the lung or scarring of the lung, said Stanford spokesman Mike Good-kind.

"The fact is this is not a procedure that would have wide application for millions of people. It is a specific treatment for a select group of child patients who are terminally ill," Goodkind said.

"The fact that it was a live-donor transplant was, in this case, subordinate to the idea that the recipient was so closely related to the donor," he said.

The 46-year-old mother and terminally ill child matched on four of six genetic markers, or tissue antigens, compared to no more than two such matches in Stanford's previous brain dead-donor lung and heart transplants, Starnes said.

Half of 14 children who have received heart-lung transplants at Stanford suffered rejection severe enough to impair lung function. That's nearly twice the rejection rate of 71 adults who have undergone the same operation, according to Stan-ford.

The girl suffers from a rare malady, called bronchopulmonary dysplasia, that causes scarring and high blood pressure of the lungs. The physical condition was the result of being placed on a respirator after being born prematurely, said Good-kind.

The malady also affects her remaining left lung but won't impair the transplanted tissue, Goodkind said.

Doctors had given the girl 12-18 months to live, but they now expect her to recover fully. Stanford doctors expect the girl to remain hospitalized for several weeks, while the mother will probably go home earlier.

Dr. Dennis Nielson, the girl's pediatrician, said she had to be persuaded to undergo the procedure.

"She believes in God and was not afraid to die," said Nielson, director of the Pediatric Pulmonary unit at the University of Utah Health Sciences Center. "She's an extremely bright little girl."

Doctors said it's likely the transplanted lung will expand capacity and may even grow.

"Dr. Starnes said the girl probably won't be a sprinter, but certainly she can go to school, participate in games and activities and go on dates, do all the normal things that kids can do," Goodkind said.

The mother's lifestyle is not expected to be changed by the procedure, Goodkind said.

"Very commonly, for lung cancer for example, an entire lung is removed. People can function normally with one lung," Goodkind said.