Hello, my name is Mara Sifry-Platt and I am
a Genetic Counselor
and Coordinator for the HDSA Center of Excellence
Partner at Kaiser Permanente.
I am also the genetic counselor at the UC
Davis
HDSA Center of Excellence in Sacramento.
You probably already know that Huntington
disease
is an inherited condition of the brain that
gets worse over time.
It can affect a person’s movements,
balance, speech, thinking, behavior, and mood.
For more than 20 years we've been able to
perform genetic testing
to determine if a person will get Huntington
disease
even before any symptoms appear.
This is called predictive or pre-symptomatic
testing. 
This video was created to give you a starting
place to think about
whether or not predictive testing might be
right for you.
One important point to mention right away
is that
we do not test anyone under the age of 18.
The only exception is when a child has the
juvenile form of HD
and is already having symptoms.
Luckily, juvenile HD is rare.
A simple blood test is all that is required
to determine whether a
person has inherited the gene that leads to
Huntington disease.
But the emotional issues around testing can
be very complex
and may catch you off guard if you don’t
take time
to think it through carefully.
So, if you’re considering predictive testing,
we strongly encourage you to work with people
who
who understand the disease and can provide
you with the best guidance and support.
Kaiser Permanente in the North Valley has
been designated a
Partner Center of Excellence by
The Huntington Disease Society of America.
Here you can work with genetics specialists,
neurologists,
as well as mental health professionals throughout
your journey.
At the end of this video you will find resources
to find
HDSA Centers of Excellence located throughout
the country.
Most genetic testing centers have a
step-by-step process for predictive testing.
This usually involves multiple appointments
where you meet with different experts.
Let me tell you how each of these specialist
helps with predictive testing.
The genetics experts may include a genetic
counselor
as well as a genetic doctor, called a geneticist.
Genetic experts, like me, explain inheritance,
ask about your family history and your personal
experience with HD.
We give you details about the gene responsible,
and let you know what to expect if you inherit
the gene.
We also talk about planning for future children
and insurance needs.
Mental health specialists are experts
who address your personal well-being.
This might be someone like a
psychologist, a social worker, or a psychiatrist.
They review any risk factors you may have
for depression, anxiety, and suicide.
They also help identify your support system.
These are the people in your life
who help you the most during hard times.
The mental health specialists support you
during
the process of predictive testing and make
sure
you’re as ready as possible to get the predictive
results.
You may also meet with a neurologist
who specializes in movement disorders.
The neurologist reviews the features of
the disease and how it's managed.
He or she might also check to see if you're
showing any early symptoms.
All of these specialists are here
to answer your questions along the way
and review the pros and cons of predictive
testing.
Testing can take anywhere from a few weeks
to a few months or even years.
It all depends on when a person feels ready
to move
to the next step in the process.
Most people who have gone through the steps
appreciate
the time we spend to prepare them for test
results.
Many times we bring up issues that you might
not think of on your own.
Although most people complete the testing
process
once they start, it doesn’t surprise us
when someone
decides to stop or take a long break between
visits.
This process can be very difficult and sometimes
frightening.
For example, in the United States, only about
1 out of 10 people
at risk for Huntington Disease choose to have
predictive testing.
Just so you know, your HD gene status
is your information if you want it.
The testing steps were set-up based on the
experience of people who’ve already gone
through the process.
There's a lot to think about before you
decide to have predictive testing
and we want you to feel prepared
for getting this important information.
At one of your first visits for predictive
testing you'll learn
about the genetics of Huntington Disease from
a genetics specialist.
To give you a head start for this visit,
we can review some of this information now.
Huntington Disease is caused by a very specific
genetic change to a person's DNA.
You will sometimes hear DNA referred to as
our blueprint
that determines things like eye and hair color.
Genes are the individual instructions found
in
that blueprint and they’re made out of DNA.
This genetic code for each gene tells the
body
how to make a protein that’s used somewhere
in the body.
The protein made by the HD gene is called
“Huntingtin.”
This protein is used in the brain and when
it’s not
made correctly people develop symptoms of
Huntington Disease.
Everyone has two copies of the HD gene,
one from their mother and one from their father. 
For most people both copies work fine.
But if even one of the two copies isn’t
working right,
that person will develop Huntington Disease.
That means a person with HD has one normal
copy
of the gene and one copy that causes the disease.
When this person has children there’s a
50/50 chance
of passing on the copy of the gene
that causes Huntington Disease.
This is what we call dominant inheritance.
Each time a person with HD has a child,
that child has a 50% risk of inheriting the
disease. 
If a family has 4 children 
this doesn’t mean that 2 will be affected
and 2 won’t. 
It's like flipping a coin each time
and each child would have their own 50% risk.
Now let’s take a closer look at the DNA
change
that leads to Huntington Disease.
DNA code is made up of four chemical bases
called
adenine, thymine, guanine, and cytosine.
But it’s easier if we just use the first
letter of each one,
so to talk about DNA in this video I’ll
use the letters A, T, G and C.
The way these letters go together is called
the DNA sequence.
And like the way the letters in the alphabet
make words,
our body can “read” certain sequences
of DNA.
In the HD gene one part of the gene includes
the sequence of “C – A – G” repeated
quite a few times.
This is called a “triplet repeat” because
these three
chemical bases are repeated over and over.
For most people, this part of the gene has
26 or fewer repeats of CAG.
When a person has 40 or more CAG repeats
we know they will develop Huntington Disease
if they live long enough.
Just so you’re aware, DNA results falling
between
27 and 39 CAG repeats are a little harder
to understand.
However this isn’t very common and all possible
results
will be reviewed in detail by your genetics
specialist.
When you have HD predictive testing we’re
counting
the number of CAG repeats on each copy of
your HD gene.
Remember you have one from your mother
and one from your father.
The number of CAG repeats you have may not
be exactly the same as your parent.
People who inherit HD from their mother tend
to
have about the same number of CAG repeats
as their mom.
However, when HD is inherited from a father,
the child can inherit a larger number of repeats.
Looking at the number of CAG repeats can give
us some idea of when symptoms may start.
In general, the higher the number, the earlier
symptoms might begin.
But there are other things that influence
when symptoms start,
so there is no reliable way to predict
this part of Huntington Disease.
In our clinics we have noticed that that people
who
exercise, eat a good diet, and have a good
support system
seem to do better than people who don’t
take care of themselves.
But researchers are working hard to learn
what
other things play a role in determining onset
and severity.
Many people who are considering predictive
testing
worry about insurance discrimination.
This is another topic commonly discussed
during the testing process.
It’s important to know that your health
information
is protected by Federal laws.
This includes the result from any predictive
testing
that you may decide to have.
The Health Insurance Portability and Accountability
Act of 1996,
also called HIPAA,
ensures your right to private and secure health
information.
This law sets limits on who can look at your
information.
It also stops group health plans from using
your health
information to make any decisions about your
policy.
The Genetic Information Non-discrimination
Act
was signed into law in 2008.
Usually just called GINA, this law specifically
protects you
from genetic discrimination by an employer
or medical health plan.
GINA was designed to make sure people are
not treated differently,
even when they have a genetic change
that can cause an inherited condition.
However, once a person has signs or symptoms
of the disease,
this law no longer applies.
But GINA doesn’t cover everything.
This law does not include protection for
life insurance, disability, or long term care
coverage.
And GINA doesn’t apply to people in the
military
or those on Native American reservations.
You can find more information
about genetic discrimination online.
We’ve provided some links where you can
learn more
about your protections under the current laws.
Predictive testing for Huntington Disease
is much more than just a simple blood test.
It is a deeply personal decision
that should be thoughtfully considered.
There are experts in Huntington Disease to
support you through
every step of the process:
before, during, and after testing.
Once you know these results,
you can’t take that knowledge away.
It will be part of you for the rest of your
life.
During the process of predictive testing
we ask you to think about many different things
like:
Why do you want to know your gene status
at this point in your life?
What will you do differently based on your
result?
What type of support system do you have in
place?
And who will you talk to as you go through
the testing?
This process is usually very emotional,
and the power of these emotions sometimes
surprises people.
This can happen even when you get a normal
test result
or when you think you are prepared for a positive
one.
The specific risks and benefits of
predictive testing are different for everyone
and are related to your beliefs, values, life
experiences,
and feelings around the future.
A genetic counselor or therapist can help
guide you through this personal exploration.
I hope this information has been helpful.
You can also check the HDSA website
to learn more about predictive testing.
If you think you’re ready to start the testing
process there is
contact information for sites in California
listed
at the end of the program.
You can also look online at the HDSA website
to find an HDSA Center of Excellence in your
area.
