'Selecting' Siblings to Help Sick Kids
Center Combines Fertility Technique, Tissue Typing to Choose Children With Lifesaving Stem Cells
May 4, 2004 -- Nine-year-old Molly Nash's life was saved by the birth of her baby brother, Adam.
Adam, now 3 1/2, was conceived by in vitro fertilization. Genetic testing of him as an embryo proved him to be a good tissue match for his sister, who was fighting a rare and potentially fatal blood disease. And doctors have delivered five more children who were hand-picked to help save the lives of older siblings.
Five weeks after Adam was born, stem cells from his placenta were transplanted into Molly, and now the once desperately ill little girl is healthy and happy. She has little memory of the illness that almost took her life.
"She was on a lot of pain medication, so she doesn't really remember," mom Lisa Nash says. "She knows that Adam gave her some blood that made her feel better. And Adam knows even less than that. When the time is right we'll tell them, but I don't know when that will be."
But could some parents abuse the ability to choose the genetic aspects of their children?
Five More Births
Lisa Nash and her husband, Jack, were the first couple to attempt genetic testing at the embryo stage to ensure that their second child would be a good tissue match for their first. Researchers at Chicago's Reproductive Genetics Institute, where they had the procedure, report their experience with nine similar cases in the May 5 issue of TheJournal of the American Medical Association.
Preimplantation genetic diagnosis, as it is called, has been used for more than a decade by couples who turn to in vitro fertilization to avoid passing on serious inherited disorders to their children. More than 100 different genetic conditions are considered worthy of preimplantation genetic diagnosis, but the Chicago fertility researchers are the first to combine tissue typing with the procedure to ensure a donor match for an existing child.
The nine couples in the study had children with leukemia or a rare but potentially fatal form of anemia. Both conditions are best treated with stem cell transplantation from a matching donor.
Researchers removed DNA from 199 eight-cell embryos following in vitro fertilization and analyzed them for tissue compatibility with the sick children. Twenty-eight matching embryos were transferred, resulting in the birth of five healthy children whose tissue matched that of their siblings.
If the couples had conceived naturally, they would have had a 25% chance of giving birth to a child whose tissue matched his or her sibling.
"Prior to this technology, tissue matching could only be done after implantation," study co-researcher Anver Kuliev, MD, PhD, tells WebMD. "Obviously interrupting the pregnancy because the fetus is not a match is a poor option."