First, the facts: The idea of genetic
testing isn’t new. As early as the 1960s, doctors
began urging that newborn babies be tested for rare diseases
they could inherit from their parents. Such diseases
are called genetic diseases because the illnesses are
contained in genes. Testing began for phenylketonuria
(PKU), a rare disease that causes mental retardation.
PKU can be prevented with a special diet if it’s
detected early. The test for PKU and other rare but treatable
diseases are now routinely done in the hospital soon
after a baby is born.
In the 1970s, researchers developed genetic tests
that could be done before a baby is born. Scientists
found that if a mother and father both have the gene
for a certain illness, their child has a high possibility
of being born with that disease. Soon, couples thinking
of having children could get tests for genes that put
their children at risk for developing sickle cell disease
and Tay Sach’s. By the 1980s, tests called prenatal
genetic tests were regularly done before a baby was
born to find out the risk of a genetic disease. They’re
now a routine part of health care in most states.
In the 1990s, researchers were able to identify genes
that showed a person’s chance of developing breast
cancer and colon cancer. People with certain forms
of a gene called BRCA-1, for example, are more likely
to develop breast cancer. Genetic testing of this type
can help you find out whether you have a “genetic
predisposition” to some diseases—in other
words, whether certain gene variations you carry make
you more likely to develop a disease. That doesn’t
mean that you’re destined to develop it; it only
means you’re more likely than those with other
versions of the gene.
“It’s important to realize that nearly
every disease has both a genetic component and an environmental
component,” Dr. Benjamin Wilfond of NIH’s
National Human Genome Research Institute explains. “You
can’t modify your genes, but you can modify your
environment to help prevent some diseases.”
Consider the common cold virus, for example. Anyone
who comes in contact with the virus could become infected.
However, some people have a genetic predisposition
that makes them more likely to get sick. If you know
this ahead of time, you can take measures like steering
clear of places where cold germs are likely to be and
taking extra care to wash your hands when visiting
public places.
Genetic testing can give us a similar head start
on fighting many diseases. People who learn early that
they’re genetically predisposed to a disease
can benefit by knowing what symptoms to look for and
potentially finding the disease in its early stages.
They may also be able to change things in their lifestyle—their
environment—to prevent the disease.
By the early 2000s, computers and other technology
had advanced to the point where large collections of
a person’s genes could be looked at, a method
called genetic profiling. In the future, some technology
companies may be able to offer genetic testing to map
your whole genome—all
the genes in your body at once! That sounds like a
dream come true for preventing disease, but the reality
is that researchers haven’t yet learned enough
to help predict your health.
“The marketing for some testing may be premature,” Dr.
Wilfond warns. “We know so little about some
of these genes, and they may be small contributors
to actual disease. There is a danger of misunderstanding
or misinterpreting the results. These tests are giving
you just small amounts of information.”
Wilfond advises people to think carefully about offers
for testing. “Ask yourself a couple of questions
before you decide,” he says. “Is this test
part of routine medical care that will help me, or
is this test something that’s only going to make
somebody a lot of money?”
In the meantime, researchers are learning more about
genetics and disease every day. “We now understand
how to look at a person’s genes for their risks
of more common diseases such as heart disease, asthma
and Parkinson’s disease,” Wilfond points
out. As scientists learn more about how environmental
factors affect genes and how illnesses develop, more
types of genetic testing will become part of routine
health care.
Television and movies—and even some marketing—often
make the science fiction of genetic testing seem like
science fact. It’s true that health researchers
are always looking far ahead to a day in science future.
Part of the challenge of genetic testing is figuring
out what to tell people until that day comes.
“There is a process for accepting new things
in medicine that happens to be gradual and that’s
good,” Wilfond observes, “because as we
wait longer, we learn more.” |
