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
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
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],"
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.