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Genetic
Counseling
Every day new discoveries unlock medical mysteries. How does this affect
your family?
by Nancy Arnott
Stop the presses! "BRCA1 Gene Found."
"Gene Unlocks Mystery of Huntington's Disease." Genetic testing has been in the headlines lately, with the
discovery of genes that can play a role in predicting an individual's
risk of illnesses such as breast cancer, Huntington's disease, and more.
Reading about these breakthroughs might have made you wonder whether
this cutting-edge scientific technology has something to offer your
family. Could genetic tests provide valuable information that could
benefit your child's health? It's possible—in some cases, genetic
testing can literally be a lifesaver.
But it's even more likely that you might seek and benefit from genetic
counseling. This is a broader category that encompasses not
only testing but also some old-fashioned medical detective work and
professional counseling.
What is genetic counseling?
Genetic counseling
is a health service that helps people identify and understand what particular
traits they might pass on to their children. It is performed by doctors
and nurses, as well as by specially educated health professionals who
are certified as genetic counselors and come from a variety of disciplines,
including biology, genetics, psychology, public health, and social work.
"Genetic counselors blend the knowledge of the science of genetics
and the interpersonal skills needed to interpret information for individuals
and couples," explains Bea Leopold, executive director of the National
Society of Genetic Counselors, an organization in Wallingford, Pennsylvania.
Genetic counselors are trained to be sensitive to the background and
values of the people they advise. A responsible counselor will never
push you toward or dissuade you from a particular course of action but
will only supply the information you need to make your own decisions.
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Genetics
Refresher Course
Understanding what determines
your child's risk of an inherited disorder means taking a quick
trip back to biology class. Here are the simple basics of genetics:
DNA (deoxyribonucleic acid) is a large molecule
that holds the instructions for making all the proteins a cell
needs.
A gene
is a piece of DNA that contains the instructions for making a
specific protein. The human body has approximately 80,000 genes.
Each plays a different part in determining a person's heath tendencies
and physical makeup-everything from his eye color to his risk
of heart disease. A child gets half of his genes from each of
his parents.
Genes
are contained in chromosomes, structures in the
nucleus of the body's cells. Human cells have 46 chromosomes,
arranged in pairs.
Genetic
inheritance patterns are classified as dominant
or recessive. If a parent passes on the gene
for a dominant disorder (such as Marfan's syndrome, a connective-tissue
disease), her child has a 50 percent chance of inheriting it.
If both parents carry a gene for a recessive disorder (such as
cystic fibrosis), their child has a 25 percent chance of inheriting
it. If only one parent has the gene for a recessive trait, it
will be overridden by the other parent's normal gene and will
not cause the child to be affected.
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Why might I want to
consult a genetic counselor?
Genetic counseling
can help you make important decisions, such as whether to have more
children and whether to seek preventive or early treatment for a disease
or disorder for which you or your child is at high risk. Situations
in which people commonly seek genetic counseling include planning a
pregnancy after age 34; having suffered two or more miscarriages; being aware of a family history of an inherited disorder;
or already having a child with an inherited disorder or birth
defect.
"People usually go for genetic counseling because a child or
another family member has an inherited disorder, which usually falls
into one of two categories," says Christopher Cunniff, MD, FAAP,
chair of the Section of Medical and Molecular Genetics and an associate
professor of pediatrics at the University of Arizona, in Tucson. "It
may be a structural problem, such as cleft lip or palate, or it may be a functional problem, such
as mental retardation or a developmental disability."
Some people also seek genetic counseling to address concerns about
serious disorders that affect their particular race or ethnic group.
Such disorders include sickle-cell anemia, a blood disorder that affects mainly Blacks;
thalassemia, another blood disorder, which afflicts mostly people of
Mediterranean (usually Greek or Italian) ancestry; and Tay-Sachs
disease,
a degeneration of the brain that strikes primarily Jews of Central or
Eastern European descent.
 When is the best time to get genetic
counseling?
If you are concerned
about passing on an inherited disorder, it's best to seek genetic counseling
before becoming pregnant. If you become aware of an inherited disorder
in your family while you are pregnant, however, genetic counseling is
still a good idea. It can help you understand the likelihood that your
child will be affected and help you prepare emotionally and medically.
If you are interested in genetic counseling because you suspect your
child has an inherited disorder, bring the matter to your pediatrician's
attention so that she can refer you to a testing and counseling facility
when appropriate. "Children can be evaluated at any
age," says Dr. Cunniff, "but the earlier it's done, the better
it is for supervising their health care. Potential problems can be treated
or at least anticipated as soon as possible."
What is genetic testing?
Genetic testing
is one tool used in the genetic counseling process. There are several
types of genetic tests. The more sophisticated blood tests analyze DNA
to determine a person's risk of developing, or passing on to his children,
specific inherited disorders.
What disorders can
genetic tests predict?
In addition to the
ethnicity-specific conditions already mentioned, serious disorders that
can be detected (or risk predicted) include cystic fibrosis, a disorder
that causes overactivity of the exocrine glands, which produce mucus;
and Huntington's disease, a degenerative
disorder that affects the brain and nervous system.
Scientists have already identified the gene that causes idiopathic
ventricular fibrillation, a condition that can cause a younger person's
heart to stop beating for no apparent reason and that leads to an estimated
15,000 to 36,000 deaths each year. They are also close to isolating
the gene responsible for autism, a brain disorder that originates in
infancy and is characterized by repetitive behavior, language dysfunction,
and the inability to interact socially.
Through sophisticated research, genes responsible for specific conditions
are being located all the time, and genetic tests are being developed
to identify them. The Human
Genome Project is an ongoing effort by scientists
throughout the world to map the estimated 80,000 genes in human DNA.
Does genetic counseling
always involve genetic tests?
No. Genetic tests
are an important tool in genetic counseling, but they are not always
needed to predict the risk of developing or passing on a disorder. A
genetic counselor can often glean a great deal of information based
on your family health history, your personal health history, and any
signs and symptoms of the disorder that you or your child might exhibit.
In some cases, standard, nongenetic medical tests can also reveal the
presence of inherited disorders.
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Creating a family health history
To help a genetic counselor
accurately assess the risk of a particular disorder, it's important
to furnish your child's complete family health history. In fact,
even if you never seek genetic counseling, it's wise to have this
record. It can be just as valuable to your child's pediatrician
as to your own physicians in helping them make decisions about
your care. Gather information on your parents (your child's grandparents),
siblings, aunts, uncles, and cousins. Make sure you canvass both
sides of your child's family-yours and your spouse's; the risk
of some diseases vary according to which side of the family the
disease has appeared in.
Here
are three starting points for assembling a family health history:
- Interview family members.
Providing
a form for them to fill out may help jog their memory and will
make your record-keeping easier.
You can obtain standard forms by calling the March of Dimes
Birth Defects Foundation, or you can visit the American Health
Information Management Association Web site at http://www.ahima.org/consumer/healthinfo.forms.html.
- Gather hospital and other medical records.
These
should include copies of any exam results, hospital discharge
summaries, and genetic tests performed on family members living
and dead.
- Request
copies of death certificates.
These
records, available from state health departments, note the person's
age and cause of death.
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If our first child
has an inherited disorder, can a genetic counselor tell us whether our
next child will have the same condition?
As a genetic counselor
will explain, the risk of inheriting a condition is the same for each
child of the same two parents. For instance, if both parents are carriers
of a recessive disorder (neither parent has the condition, but they
are able to pass on the gene for it), each of their children will have
a 25 percent chance of inheriting the disorder, a 50 percent chance
of being a carrier but not having the condition, and a 25 percent chance
of having neither the disorder nor the gene for it. These risks will
be the same for each of the couple's children, no matter how many offspring
they have.
Some birth defects, however, are thought to result from a combination
of genetic and other factors, such as the mother's diet, health, and
exposure to environmental influences. These defects include spina bifida and cleft lip and palate. According to the
March of Dimes Birth Defects Foundation, these defects are much less
likely to happen more than once in a family. The risk of a second child's
suffering from one of these problems is estimated at about five percent.
 Are genetic tests ever performed on
children, or only on parents?
Some genetic tests
can be performed on children as well as on parents. In fact, screening
tests for certain genetic disorders, such as sickle-cell anemia, are
routinely performed on newborns. Some inherited disorders, such as Wilson's
disease (a liver and mental disorder) and glaucoma (a sight-threatening
buildup of pressure inside the eye), are not always apparent at birth.
If you have a family history of such a disorder, ask your pediatrician
about having your child examined or tested for it as early as possible.
What is the benefit
of knowing that my child has an inherited disorder or is at increased
risk of having one?
Once they have
been identified, some conditions can be successfully treated and their
symptoms prevented or minimized. Metabolic disorders, for example, can cause serious problems if they
aren't addressed, but they can be treated effectively by avoiding certain
foods or nutrients or by taking certain supplements.
Knowing your child's prognosis can also enable her pediatrician and other
health-care providers to anticipate possible complications and be ready
to treat them early on. Dr. Cunniff cites neurofibromatosis, a genetic
disorder that causes multiple growths on the skin or tumors inside the
body, as an example. "If your child has such a disorder, your pediatrician
can schedule screenings for tumors at regular intervals so they can
be caught in the early stages," he says.
Discovering an inherited disorder in the prenatal period can help you make choices that may
dramatically affect your child's well-being. "It can affect the
management of your delivery, as well as the care and testing the newborn
receives," says Dr. Cunniff. As an example, he says, "When
we know a baby has spina bifida [a failure of the bones in the spine
to fully fuse], we generally recommend Cesarean
delivery, which can improve the neurological outcome because it lessens
the risk of trauma to the spine."
Prenatal diagnosis also provides other benefits, says Leopold. "Knowing
about an inherited disorder in advance gives parents time to adjust
to the reality of the situation and to get in touch with other families
and support systems that can help ease their way."
As a child grows, being aware of his disorder can help parents set
realistic expectations for his development and prepare emotionally for
the challenges of dealing with his condition.
How can I find a qualified
genetic counselor?
Your obstetrician or pediatrician can help you decide whether
genetic counseling might be helpful in your situation and refer you
to a genetic counselor if necessary. Other referral sources include
the March
of Dimes Birth Defects Foundation at
(888) 663-4637 and the National Society of Genetic Counselors at
(610) 872-7608.
Nancy Arnott is a writer in New York City who specializes in health
topics.
The article on this page was submitted by Laura Broadwell, NWHIC's
Guest Editor of the month, from Healthy Kids Magazine.
The
National Women's Health Information Center
A Project of
The Office on Women's Health in the
Department of Health and Human Services
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