MINNEAPOLIS – In the first known case of its kind, a couple had several embryos created in a lab and selected one to produce a child that was free of a genetic disease and able to provide a transplant to save the life of his 6-year-old sister.
Last week, doctors at the University of Minnesota infused blood from the umbilical cord of 5-week-old Adam Nash into his sister, Molly, to try to fight Fanconi anemia, a rare genetic disease that could kill her because she can’t create her own bone marrow.
Doctors should know within about a week if stem cells contained in Adam’s cord blood are helping Molly develop healthy marrow cells.
It is widely considered ethical to screen embryos for genetic diseases because it is best for the child, said Jeff Kahn, director of the university’s Center for Bioethics.
But the case of the Nash family, from Englewood, Colo., is different. The cells that grew within Lisa Nash’s womb into Adam also were selected for traits that would benefit someone else – his sister.
It is the first time genetic testing has been used by parents to select a child who is both free of a disease and the best tissue match for a sibling who needs a transplant to fight that disease, said Dr. Charles Strom of the Reproductive Genetics Institute in Chicago, where Lisa and Jack Nash had Adam conceived.
The Nashes wanted additional children, but had been afraid to conceive because both carry a faulty version of the Fanconi gene, meaning each child would have a 25 percent chance of developing the disease.
“We wanted a healthy child,” Lisa Nash said before the transplant. “And it doesn’t hurt him to save her (Molly’s) life.”
Among the first couples to acknowledge publicly that they conceived a child as a transplant donor were Abe and Mary Ayala of Walnut, Calif. But they couldn’t select an embryo a decade ago and had only a 1-in-4 chance that daughter Marissa-Eve would be a suitable donor of bone marrow to fight her teen-age sister’s leukemia. Marissa-Eve, born in 1990, turned out to be a suitable donor and Anissa Ayala recovered from the disease and later married.
When Molly Nash was about 18 months old, her parents learned of a process called pre-implantation genetic diagnosis, or PGD.
In the procedure, performed at the Chicago institute, a woman takes drugs to stimulate the production of multiple eggs, which are fertilized by her husband’s sperm in a laboratory dish.
The resulting embryos are tested, and embryos found free of a specific disease and considered good matches for transplant are implanted in the mother’s womb.
The Nashes went through the process five times before the selection of an embryo that led to Adam’s birth.
At the University of Minnesota, the Nashes are the first of about a dozen families with genetic diseases working with Dr. John Wagner, a nationally recognized expert in cord blood transfers and Fanconi anemia.
Wagner said 98 percent of people with Fanconi anemia have bone-marrow failure by age 35 and half of them have it by 7.
The best treatment is a transfer of stem cells found in the umbilical blood of a sibling because the recipient’s body is not likely to reject them, Wagner said. Stem cells can develop into bone marrow cells.
Wagner said the survival rate for someone with Fanconi anemia is 31 percent after a transplant from someone who is not related, but that jumps to 85 percent for blood from a sibling.
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