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Family Planning

Experts recommend genetic testing for couples before conception.

Ruthan Brodsky | Contributing Writer

C

ouples eager to start a family often
include genetic testing and carrier
screenings in their preconception
plans to improve their chances of having
a healthy baby. Perhaps one person has a
family history of a particular genetic disor-
der and wants to know if she and her part-
ner are at risk for giving birth to children
with specific genetic disorders.
They both understand that genetic
screening may confirm their carrier status
for that particular disorder, enabling them
to make choices based on today’s many
options for starting a family.
The terms genetic screening and genetic
testing are often used during pregnancy,
and their meanings are frequently inter-
changed. They both use laboratory tests to
identify the presence of specific changes
in genes that may cause genetic disorders.
Genetic testing, however, is usually offered
to people already suspected to be at high
risk for a particular genetic disorder
because of a prior personal or family histo-
ry. Genetic testing is also sometimes used
to help doctors decide on the best medi-
cine or treatment for specific individuals.
Carrier screening is used to find people
the Center for Molecular Medicine and
who carry a change in a gene linked to a
Genetics, Pediatrics and Pathology at
disease. They usually show no signs of the
Wayne State University School of Medicine.
disease themselves but have the
“It is particularly important for
ability to pass on the gene change
the Ashkenazic Jewish population
to their children who may become
because they are at higher risk
carriers.
than the general population for
Couples do genetic testing to
many specific genetic disorders.
look for changes in genes that
Other racial and ethnic groups
cause them not to work properly. If
have different genetic diseases that
a baby inherits the same non-work-
are more common in their groups.”
ing gene from both parents, that
The Ashkenazi Jewish Genetic
Dr. Gerald
can lead to certain genetic diseases. Feldman
Panel, AJGP, covers those dis-
These are recessive disorders,
eases that occur more frequently
meaning that each parent needs
in people of Eastern European
to pass a non-working gene to the baby for
(Ashkenazi) Jewish descent rather than in
the child to be affected. But, if the mother
the general population. The AJGP test tells
screens positive for a genetic abnormality
parents if they have an increased chance
and the father doesn’t, their child isn’t likely of having a child with certain genetic dis-
to inherit the condition. Even if both moth- eases.
er and father screen positive, there’s only a
“During the past several years and pri-
25 percent chance with each pregnancy that marily as the result of newer technologies,
their baby will have the disease.
the AJGP has been expanded by some
“Genetic screening is important for all
laboratories to include 80-plus disor-
couples preparing to start a family,” says
ders,” Feldman says. “Different labs may
Jerry Feldman, M.D., Ph.D., professor, at
have different tests in the panel they use.

40 October 27 • 2016

There’s no such thing as a standard panel
anymore.”

Pan-Ethnic Screening

“In addition, the trend now is toward pan-
ethnic screening, a more comprehensive
screening panel that includes common
genetic disorders for the Ashkenazic popu-
lation as well as for other ethnic groups
and minorities,” he says. “New technolo-
gies make it viable to offer carrier screen-
ing for a large number of recessive condi-
tions that affect people of many different
backgrounds.”
Again, those laboratories offering pan-
ethnic screening have different disease and
mutation panels that make genetic counseling
helpful when one or both members of the
couple have abnormal screening results.
“We have about 20,000 genes in every cell
of our body,” Feldman explains. “Our genes
come in pairs — one copy from our mother
and the other copy from our father. When a
given gene has an error in it, it doesn’t work
properly and can’t do its job. We call this a
mutation.”

Genetic screenings are a proven method
to decrease the prevalence of genetic diseas-
es. For example, Tay-Sachs disease (TSD)
carrier screening, initiated in the 1970s, has
reduced the birth-rate of Ashkenazi Jews
with TSD worldwide by 90 percent.
“Once it’s known whether both partners
are carriers for a specific Jewish genetic
disease, the couple can then explore ways
in which to have a baby born without that
genetic condition,” Feldman says. “Some
of these options include sperm or egg
donation, in-vitro fertilization(IVF) with
pre-implantation genetic screening and
adoption. The couple may also choose not
to have children or may choose to have
prenatal testing to determine if the fetus is
affected with that disorder.”
Preimplantation Genetic Diagnosis
(PGD) is a procedure used prior to implan-
tation to help identify genetic diseases in
embryos created through in-vitro fertiliza-
tion so that the specific disorder is not
passed on to a child. Following the normal
process of in-vitro fertilization that includes
egg retrieval and fertilization in a lab, one
or two cells are removed from the embryo
and evaluated to determine if a mutation
is present. Only those embryos found to be
free of specific genetic problems are placed
back in the uterus and implantation is
attempted. Embryos free of those specific
genetic changes can also be frozen for pos-
sible later use.
“One of the major benefits is that the
procedure enables couples to give birth to
biological children without having to be
faced with that 25 percent risk of a specific
genetic disorder,” Feldman says. “More
common, however, are those requests we
receive for genetic testing from women who
are already pregnant. Their choices of what
to do next following the screening are more
limited because PGD is not an option for
that current pregnancy.”
It is recommended that those seeking
more information about genetic screening
and options should consult their insurance
carrier regarding coverage for costs prior
to testing.

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(For a sidebar on JScreen’s genetic testing
program, go to page 44.)