Her mother calls her a "trooper." Her transplant surgeon describes her as a "tough kid ... spunky." High praise indeed, but insufficient to describe what Isabelle Christenson, of Seven Fields, has overcome in her 10 years of life.

Because of complications caused by a genetic disease called mitochondrial disorder, Isabelle underwent at age 6 a multivisceral transplant that replaced her liver, stomach, small bowel, pancreas and duodenum. Fewer than two years later, she had a kidney transplant, too.

She also has had several strokes that temporarily cost her the ability to walk or talk, and she took nourishment through a feeding tube until the first transplants afforded the opportunity to learn how to eat real food. Lacking a complete colon, she has an ostomy.

Yet through it all, Isabelle has managed to cobble together a normal life, going to school, acting in a local theater production of "Annie," singing, doing arts and crafts and playing with her Shih Tzu, Lucy.

Now, Isabelle has been practicing softball as preparation for her competition in the National Kidney Foundation 2008 U.S. Transplant Games in Pittsburgh July 11-16. A member of Team Pittsburgh, she also will compete in bowling and walk in a 5K race that is open to the public.

"She doesn't know any better," said her mother, Michelle Christenson. "She plugs along. She does what she can do."

And that "great spirit," says transplant surgeon Dr. Kyle Soltys of Children's Hospital of Pittsburgh of UPMC, is what got her through the transplants, particularly the multiorgan one.

"It's her personality. That's done it all," he said. "She's a tough kid. She's spunky. ...

"She has up days and down days, up weeks and down weeks. There is pain with mitochondrial disorder. She has had many, many different issues," he added. "But when she's not having a bad time she goes back to being spunky."

Mitochondrial disorder is a cellular metabolic disease of which there are many types. "She has a very specific type that can affect the brain, nerves, the heart, muscle," Dr. Soltys said. It also can affect the bowel, which is what happened to Isabelle. "She came to us with [chronic pseudo-obstruction immune deficiency] in 2004 because she couldn't eat," he said. "The bowel didn't work."

Because of that, she was on TPN, a type of intravenous nutrition that can cause liver damage, which Isabelle also had to the point that the liver no longer worked, either.

"She came to us with both the intestine and stomach not working and the liver not working because of TPN," the surgeon said. "Both went back to the mitochondrial disorder."

It was, he explained, a vicious circle: "Because the bowel didn't work, she got food by vein, which damaged the liver."

The multivisceral transplant kept her from dying from liver and intestinal failure, but the mitochondrial disorder itself has no cure.

Similarly, she needed the kidney transplant because hers were damaged by one of the antibiotics she took for multiple infections and immunosuppressants.

The multivisceral transplants have a high rate of success, Dr. Soltys said, with 85 percent of the patients still surviving after five years. But, he explained, "her survival will be limited more by the mitochondrial disorder than her transplants, and we don't know how long someone is going to survive with mitochondrial disorder."

He added, "there are adults with mitochondrial disorder ... She will probably be brightening our office for a long time to come."

For more information about the Transplant Games, visit www.transplantgames.org.