Information and Resources

Sibling Selection

June 26, 2001 -- Parents of sick children will go to great lengths to find something that will save them. Some are even willing to have another child in hopes of creating a match who can donate healthy blood cells for the sick sibling.

Advances in research now make it possible to virtually guarantee parents such a match. But ethics experts worry that the potential good comes at too great a price.

Case in point: Parents of a girl born with a rare, incurable disease -- called Fanconi's anemia -- underwent a controversial procedure to conceive another child who could help cure their daughter. Embryos harvested from in vitro fertilization, or IVF, were tested for signs of the gene responsible the disease. Embryos that did not carry the genetic abnormality underwent further testing to isolate those that would be a safe donor match for the girl.

In Fanconi's anemia, which typically strikes children, the bone marrow fails to produce blood cells normally. Available treatments only can reduce complications of the disease. People with this disease die, on average, in their early 20s.

After four IVF attempts, the mother gave birth to a healthy boy. Blood from his umbilical cord was infused into his sister shortly after he was born last year.

Both children are now fine, and the girl, Molly Nash, is healthy and attending school. Her parents, who are both carriers of the anemia gene, have said they had planned to have more children and that this allowed them to have another healthy child, who they named Adam, while at the same time providing a donor for Molly.

"I don't think there's any negative about this," says Yury Verlinsky, PhD, lead author of a report about the case in the June 27 issue of Journal of the American Medical Association. "I think it's completely ethical, more ethical than anything that can be done in this situation."

But many do question parents choosing to bear a child free of disease for the purpose of being a donor. Others wonder how far away we are from choosing traits such as eye color or personality.

The testing Verlinsky's group did -- pre-implantation genetic diagnosis, or PGD -- is already used to detect genetic defects including the rare blood disorder hemophilia, cystic fibrosis, and sickle cell anemia, in embryos. This is the first time it's been used to match potential donors and recipients.

Verlinsky, director of the Reproductive Genetics Institute in Chicago, believes there is little risk of people abusing the technique because it is so involved. A couple has to undergo numerous tests and endure multiple IVF attempts, all of which are costly and time consuming.

Another concern is discarded embryos. In this case, 24 healthy embryos resulted, but only five were a match for Molly and only one resulted in a pregnancy. So, 20 healthy embryos that theoretically could have produced a life were discarded.