Sickle Cell Anemia and In Vitro Fertilization: Preimplantation Selection of Non-Carrier Embryos Produces Healthy Twins
Nov. 16, 1999 (Seattle) -- A technique called preimplantation genetic diagnosis (PGD) has allowed a couple with sickle cell trait to have twins whose healthy genetic status was known before pregnancy, a Cornell team reported in a recent issue of JAMA. The team says that it believes the births are the first from embryos screened for sickle cell trait before implantation following in vitro fertilization.
The twins were born to a 34-year-old woman who had undergone two previous induced abortions because the fetuses were affected with sickle cell anemia.
To avoid another unsuccessful pregnancy, Cornell researchers used in vitro fertilization to produce seven embryos for genetic testing. A single blastomere (cell produced during fertilized-egg cell division) from each embryo was removed and tested for sickle cell trait. The tests showed that four embryos were normal and two were sickle cell carriers. (The team was unable to determine the status of the remaining embryo.) Three healthy embryos were transferred to the woman's uterus, resulting in a twin pregnancy that produced healthy babies.
Zev Rosenwaks, MD, co-author of the journal article and director of Cornell's Center for Reproductive Medicine and Fertility, tells WebMD that the team used standard PGD techniques. "It's been applied before to sickle cell," he says. "But we believe this is the first instance where a pregnancy was established and indeed the affected fetuses were normal."
Despite earlier failures, Rosenwaks says, there's no reason to believe PGD will be any less effective for sickle cell anemia than for diseases such as Tay-Sachs and cystic fibrosis. "We expect this would be applicable and efficient in most cases for this disease," he says.
Rosenwaks says that adding sickle cell to the list of diseases for which PGD works is important, because it's a relatively common genetic defect that forces many women who become pregnant to make an agonizing choice. "The reason a couple chooses to undergo PGD is to eliminate a potentially lethal or devastating disease and also to avoid having to have a therapeutic abortion when and if they discover the fetus is affected after [prenatal testing]," he says.
William Gibbons, MD, clinical director of the Jones Institute PGD team, says that he hopes publicity about the sickle cell test will encourage more people to request PGD and more insurers to cover it, even though it adds about $3,000 to the cost of in vitro fertilization.
"It's less expensive to do the test than to cover the medical costs of children born with serious genetic diseases," he says.