TULSA, Okla. (AP) -- When Marion Weber needed a life-saving bone-marrow transplant, she didn't have to look far for a donor.
"I knew whatever she needed I would give her," said her twin sister, Kathryn Burke. "She didn't even have to ask."
"Not a single word was said," Weber said. "We didn't discuss it. Of course she would help me."
The two are exceptionally close. They attended school together, moved to New York together and rode horseback together.
Dr. Joseph P. Lynch of Oklahoma Oncology says Weber was extremely lucky to have an identical twin to donate the stem cells.
But they each had to overcome an obstacle: age.
Stem-cell donors and recipients are usually younger than 50, which the twins exceeded by a couple of decades, although they won't reveal their age.
Weber suffered from aplastic anemia, an unexplained failure of the bone marrow to produce all blood cells -- red, white and platelets. Aplastic anemia affects one in a million people.
Before a stem-cell transplant, the diseased bone marrow is killed with chemotherapy and replaced with healthy bone marrow stem cells that grow into healthy blood cells.
In the twins' procedure, Lynch filtered out half a liter of stem cells from Burke's blood.
He transfused the cells into Weber's bloodstream.
Stem-cell transplants are still a relatively new procedure -- only about 10 years in practice, Lynch said. Last year, St. Francis Hospital doctors performed 35 bone-marrow transplants. This year, Lynch expects 50.
Weber was more than fortunate to have an identical twin as a donor.
"If she were not an identical twin, we would not have transplanted her," Lynch said. "The mortality rate would have been astronomical."
"I didn't moan or groan or say, `I want to die,"' Weber said.
But she does offer one piece of advice for others in her situation: "I highly recommend that when you go to a hospital, you ignore everything," she said. "You'll be much happier."