Ensuring Your Baby Will Be Healthy:
Embryo Screening Test Gains in Popularity and Controversy; Choosing
a Child's Gender
Amy Dockser Marcus
The Wall Street Journal
July 25, 2002
At 39 years old, shortly after his son, Jarred, was born,
Jeffrey Sowers was diagnosed with myotonic dystrophy, a common
type of muscular dystrophy. The Sowers had been planning on
trying to have another child—until doctors told them there
was a 50% chance their children could get the debilitating disease
"After that we figured that Jarred would be an only child,"
says Melanie Sowers, a 38-year-old accountant. "It wasn't
worth taking the risk that our children might get sick."
Then the Sowers, who live in Temecula, Calif., found out about
a medical procedure that could potentially ensure that any future
child they had wouldn't get their father's disease. Called PGD,
or preimplantation genetic diagnosis, the technique requires
couples to conceive through invitro fertilization, a common
procedure used to combat infertility that unites egg and sperm
in a laboratory. But before implanting the resulting embryos
in the woman's womb, doctors test a cell from each of them.
They place only embryos that are free of the disease in the
PGD, introduced a little over a decade ago, is starting to
boom and some doctors say it could, in time, become a common
-- albeit hugely expensive -- method of prenatal screening.
Over 40 centers in the U.S. and abroad now offer the procedure,
and over 300 children have been born through the method world-wide.
At the Institute for Reproductive Medicine and Science of Saint
Barnabas in Livingston, N.J., one of the major PGD centers in
the U.S., the procedure was done 400 times last year. In recent
years, the clinic has reported a 50% annual increase in cases.
Shady Grove Fertility Centers, a large Washington, D.C., area
based infertility clinic, started its own PGD program this month.
"Soon PGD will be used as regularly as amniocentesis
now is," predicts Santiago Munne, the PGD program director
at Saint Barnabas.
But the technique is increasingly being used for other, far
more controversial, screenings. It has been successfully employed
to find an embryo with matching bone marrow to donate to a sick
sibling -- meaning that otherwise healthy embryos had to be
discarded. But most upsetting to some people: PGD is also being
used by couples who want to select the gender of their child.
"When we do patient surveys to see why people want PGD,
many say they want it for family balancing" in terms of
gender, says Dr. Munne of Saint Barnabas. (Saint Barnabas does
gender selection only when there is a risk of sex-related diseases.)
The key to PGD's growing popularity is it is done before a
woman is pregnant. Other prenatal tests are performed weeks,
even months, into a pregnancy. If a problem is discovered, "you're
already pregnant and have to decide whether or not to terminate
the pregnancy," says Dr. Arthur L. Wisot, the executive
director of Reproductive Partners Medical Group in Beverly Hills,
Calif., and one of the Sowers' doctors. PGD eliminates such
a wrenching experience, allowing a couple to choose which, if
any, embyros to implant in the woman's womb.
Consequently, PGD is becoming an increasingly important tool
for women trying to get pregnant after the age of 35, when the
risks rise of having a baby with extra or missing chromosomes,
which leads to birth defects or recurrent miscarriages.
The growing interest in the procedure comes despite some serious
drawbacks. There is up to a 10% rate of error in detecting the
genetic abnormality, which means it's not as accurate as amniocentesis
or chorionic villus sampling, the two most common common prenatal
tests. That's because PGD uses a single cell from the embryo
so there is only a small amount of chromosomal and genetic material
to examine; one test can't examine every chromosome or screen
for every disease.
It also comes at a much higher price tag than standard prenatal
tests: anywhere from $2,500-$3,500 for the PGD test and as much
as $20,000 more to undergo invitro fertilization with the healthy
embryos. Some insurance plans will cover it; others won't.
Consequently, PGD is most widely used by couples who know
they have a risk of Tay-Sach's disease, hemophilia, Gaucher's
disease, sickle cell disease, thalassemia and dozens of other
genetic conditions that are passed down through one or both
But there are many additional people who might want to use
PGD. Genetic counselors say the prevalence of these diseases
is more common than people suspect. Everyone has a 3-5% chance
of having a baby with some kind of defect. In countries where
there is a strong social, religious, or economic preference
for boys, such as India and Jordan, PGD is often used to ensure
having a boy.
Even in the U.S., using PGD for gender selection is on the
rise. Some centers, or doctors, will do the procedure for that
pupose; others won't. At the Sher Institute of Reproductive
Medicine, a fertility clinic whose main office is in Las Vegas,
Nev., "We allow gender selection for family balancing,"
says Dr. Geoffrey Sher, who heads the clinic. "If someone
has three girls and they want a boy, we say sure." But
he says the clinics will only allow gender selection for the
sex that the family does not already have.
Before PGD is performed, a woman needs to take drugs that
stimulate the production of her eggs and undergo surgery to
remove them. Then one of two procedures is done, depending on
what conditions pose the highest risk. The geneticists may examine
two small cells from the ripening egg called polar bodies, which
are removed from an opening in the covering of the egg and analyzed
for chromosomal or genetic conditions. In other cases, the embryo
itself is analyzed by making an opening in the covering of the
embryo during the third day of development and removing one
of the embryo's 8-10 cells.
Given how arduous the process is, most of the people using
PGD are still like the Sowers, who don't care whether they have
a boy or a girl but urgently want to avoid passing on a genetic
disease to their children. Ms. Sowers has undergone the procedure
two times, but she failed to get pregnant.
The couple plans to use PGD for any further attempts to conceive
a child. Meanwhile, they still don't know the fate of their
son, Jarred. On the advice of their neurologist, they aren't
going to have him tested for mytonic dystrophy at this stage
and so far he is showing no symptoms of the illness.
But their experience with PGD has made them realize the precarious
odds of having a healthy child the conventional way. The first
time they did PGD in February, they learned that eight of the
13 embryos they created had the disease; the second round, in
June, resulted in two affected embyros out of five, and a third
that stoped growing in the Petri dish.
"I was surprised at those statistics," says Ms.
Sowers. "It scared me again for Jarred."
Some Clinics That Offer PGD
-- The Institute for Reproductive Medicine and Science of
Livingston, New Jersey; www.sbivf.com
-- Molecular Medicine and Genetics at Wayne State University
-- Reproductive Genetics Institute
-- Shady Grove Fertility Reproductive Science Centers
-- Sher Institute for Reproductive Medicine
Las Vegas, Nevada; www.haveababy.com
Source: the clinics
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