What does presymptomatic testing entail?
The Huntington's Disease Society of America recommends that at-risk persons
who wish to undergo presymptomatic testing do so at an HD testing center.
The testing centers involve teams of professionals who are knowledgeable
about HD. A list of these testing centers is available from HDSA.
The testing procedure involves sessions with various professionals. It typically
includes one session devoted to each of the following: genetic counseling; a
neurological exam; a psychological interview; discussion of the results; and
follow-up. The genetic test itself is a blood test.
The purpose of these sessions is to ensure that the person about to undergo
testing understands the implications of this knowledge and is prepared to
receive the results. The neurologic exam will determine if any early symptoms
of HD are present. If the person is found to be symptomatic, he/she will be
offered the option of discontinuing the test procedure.
The person may withdraw from the testing process at any time.
The sessions of the testing process are usually spread out over one month or
more and require repeat visits to a testing center. Exceptions are sometimes
made if a person lives far away from the center or in other circumstances.
Decisions concerning scheduling of appointments can only be made by those
who will perform the testing.
Should I bring a friend with me?
It is strongly encouraged that you bring a support person/partner with you
to all testing sessions. The partner should be a spouse, companion or a close
friend. It is not advisable to bring a sibling or another person who is at risk for HD.
The partner will be able to provide moral support during appointments, when
awaiting test results, upon receiving the results, and thereafter.
Are blood samples from my family members necessary for testing?
No, you do not need to obtain blood samples from others in your family. However,
the testing centers do encourage you to have available either a blood sample from
a family member who has HD or the results of his or her genetic test. This is to
ensure that the illness in the family is indeed HD. Some people are misdiagnosed
as having HD when, in fact, they have another neurological disorder. Therefore it
is important to establish that the affected family member has HD. This type of
testing is usually reimbursable by insurance.
The cost of testing varies from center to center. Some centers are research facilities
and will perform the test free of charge for those involved in their studies, some
have sliding fee scales, and others charge anywhere from $600 to $1,500.
Will health insurance pay for testing?
You need to check with your insurance provider to see if they cover presymptomatic
testing. However, before doing so, you should weigh the risks and benefits of
submitting a claim. Unfortunately, genetic discrimination does exist. Though
unusual, it is possible for an insurance company to deny health coverage or to
cancel an existing policy should a person be found to carry the HD gene. A positive
test result may also be considered a "pre-existing condition" which could make it
difficult to obtain future health insurance coverage. In a number of states, laws
do exist which prohibit genetic discrimination by insurers, and a similar federal
Many people choose to wait until they have the results of their genetic test before
seeking reimbursement from their insurance company. They then do so only if
they do not have the gene.
Are the results of the test always accurate?
The accuracy of positive or negative results is almost 100 percent provided that
another family member is known to have the gene for HD. Test results cannot
determine if a person will develop HD if the number of CAG repeats falls into the
intermediate range. Also, positive test results cannot predict when the symptoms
Are the test results confidential?
Test results should be kept confidential and should only be given to another person
with your written permission. On an initial call to a testing center, you should ask
how confidentiality is ensured.
If the test results cannot tell me when the disease will begin, how will I know if
I am beginning to show symptoms?
HD can only be diagnosed by a neurologist. A neurological exam can determine
if you have symptoms of HD.
Should I be tested for HD?
The decision to undergo genetic testing is an intensely personal one that cannot
be taken lightly. Testing should never be mandated or forced upon an at-risk
individual. There are no "right" or "wrong" answers. Of course, everyone will
have his/her own circumstances to take into consideration. The following are
some of the issues to think about and/or discuss with those who are closest
Will your relationship with your spouse or significant other change once your test
known? Does he/she want you to take the test? How will a positive or
impact your future together?
Relationships with siblings are sometimes strained by learning a test result.
There is often
guilt felt by siblings who do not carry the gene (although they had
no control over which gene
they inherited). Those who have the gene may
express anger toward brothers and sisters
who do not.
Children often factor heavily in the testing decision. Many people undergo
testing before planning a family. Others use the result to decide
if they will have more children.
Those who already have children worry about
the impact of a positive test result. They may
ask themselves questions such
as: How will I tell the children that they may have inherited the
gene from me?
How will I explain to them that I will one day show the symptoms of HD?
will this affect their lives?
Parents may feel guilty for having had children knowing that HD was in their
family (even if they
were not aware of their own risk for inheriting the gene at
the time they had children).
Your relationship with your parents may also be affected by the test result.
Parents may feel
guilty for passing on the gene. An unaffected parent may
upset by the thought of having to
watch his/her child live with HD. A
may also have mixed emotions in the event that one
negative for the
HD gene while another tests positive or begins to show
Friends are among those to whom we turn for support. You may choose to tell
a close friend
(or friends) about your decision to be tested for HD. Should you
choose to be tested, make
certain that you share your decision only with people
ou trust will not discuss it with others.
Most people will have a strong emotional response (either immediate or
in the future)
when they are told whether they do or do not carry the gene.
most people adjust well
to the results after some time has passed.
Where can I find help in making this decision?
There are different resources available to aid you in making your decision.
The HD testing centers are staffed by professionals with the knowledge and
expertise to help
you decide whether or not to take the test. If you want long
-term counseling, an HDSA chapter
social worker or the staff at the HD
center may be able to provide you with a referral to
You may also consider joining a support group. There are HD support groups
state and some groups are specifically for those who are at
Your local HDSA chapter or
the HDSA national office can help you locate
group in your area.
It is often helpful to read how others arrived at their decisions. Two publications
this are Experiences of Predictive Testing for HD (a collection of
accounts - available
from HDSA as part of the Testing Packet)
A memoir of Family, Risk, and
Genetic Research by Alice Wexler
(published in 1995
by Random House).
Another helpful resource is Walking the Tightrope: Living at Risk for Huntington's
Randi Jones, Ph.D. This book provides professional insights and
at risk for HD.
Is there a "right" time to be tested?
Although all of us face stresses in our daily lives, one should not undergo testing
the time of a
particularly stressful event (a death in the family, divorce,
HD in a loved one, or some
other traumatic experience).
Should children be tested?
Testing of children (those under 18 years of age) is strongly discouraged.
symptoms of HD, a neurologist who is familiar with
Genetic testing may
then be recommended as
in some cases.
Given that each person should decide for him- or herself whether or not
to be tested,
wait until they can arrive at this decision for
themselves. Testing of
children may also
them to discrimination
by health insurance companies,
employers, and perhaps
unconsciously) by their parents.
Is prenatal testing available?
It is possible to determine if a fetus is carrying the gene for HD. The prenatal
currently available are amniocentesis and chorionic villus sampling
(CVS). It is advisable for a couple to discuss prenatal testing options with a
genetic counselor prior to becoming pregnant. If an at-risk partner wishes to
tested for the HD gene, it is recommended that the testing process be
If the parent who has a 50 percent risk for HD does not wish to undergo
but the couple wants prenatal testing, then nondisclosing tests can
Nondisclosing testing is performed by linkage analysis. Linkage
the chromosomes obtained from the blood samples of
several family members to
those of the fetus. In this way, the risk that the
fetus is carrying the gene for HD
can be estimated. A genetic counselor should
be consulted well before conception
since blood samples from family members
must be obtained and analyzed in this
type of testing.
What is confirmatory testing?
Confirmatory testing is used to "confirm" a neurologist's suspicion that a
HD. It is a type of genetic testing which is often performed by a
neurologist when a
patient has symptoms which appear to be those
associated with HD.
It is important to bear in mind that, even though a person may be aware
that he or
she has some of the symptoms associated with HD, hearing this
can often have a significant psychological effect.
How can I find out where testing centers are located?
The HDSA publishes a list of testing centers which is available free of charge.
Is any research being done to find treatments or a cure for HD?
The key to better treatments and an eventual cure is research. There have
exciting breakthroughs in recent years, including finding the gene
that causes HD in
1993. In 1995 huntingtin-associated protein (HAP 1), a
protein which works along with
huntingtin (the protein which is expressed
by the HD gene), was discovered. Research
is underway to determine how
these proteins, and possibly others, are tied to the
symptoms of HD.
An international coalition of scientists, known as the Huntington Study Group
was formed in 1993 to conduct clinical and basic scientific research in
systematic fashion. HSG sites combine research facilities with
teams of professionals
who have expertise in treating HD. The Group has
begun to test new drugs which could
potentially lead to effective treatments
In 1997, the Huntington's Disease Society of America established the HDSA
for the Cure, a consortium of 14 top laboratories in North America
and Europe. Coalition
investigators focus on four key areas of study: animal
models, cell models, biochemistry
and cell biology. Through HDSA funding,
semi-annual meetings and the sharing of data
and ideas, the Coalition is
accelerating the pace of HD research.
While there is currently no cure for HD, treatments are available which can lessen
severity of some of the symptoms. A neurologist or psychiatrist who is
about HD can prescribe appropriate medications, and physical,
occupational and speech
therapists should also be consulted in the early stages
of HD to be optimally effective.
Where can I go for more information?
Additional publications bout Huntington's Disease, genetic testing, and related
be obtained from
Huntington's Disease Society of America
158 West 29th Street,
1-(800) 345-HDSA or (212) 242 1968.