Download Huntington`s Disease

By: Catherine Peters
What is Huntington’s or Huntington's
Chorea?
Huntington’s disease is an incurable hereditary
brain disorder in which nerve cells become
damaged, causing various parts of the brain to
deteriorate. The disease affects movement,
behavior and the affected individuals' abilities to
walk, think, reason and talk. These functions are
gradually eroded to such a point that they
eventually become entirely reliant on other people
for their care. People usually start to show
symptoms at 30-40’s of age. There is no effective
treatment.
The brain of a Huntington’s Patient
As you can see, the brain on the HD patient has deteriorated.
HISTORY OF HUNTINGTON’S

Before the 19th century, some HD
sufferers were thought to be
possessed by spirits or persecuted as
witches, and were shunned or exiled
by society. The first thorough
description of the disease was by
George Huntington, who openly
accommodated those with HD and
studied them, in 1872. Examining the
combined medical history of several
generations of a family exhibiting
similar symptoms, he realized their
conditions must be linked.
Huntington's Disease was mentioned in medical literature for the
first time in the 1840s. Three young doctors writing in three
different countries, England, Norway and the United States,
described people afflicted with involuntary movements and
mental disturbances inherited from a similarly affected parent.
In 1872, Dr. George Huntington wrote a landmark paper
accurately describing the disease and stressing its hereditary
nature. He was the third generation in a family medical
practice in Long Island, New York. From the doctors'
combined experience of a family with the same symptoms in
each generation, he documented his observations and the
disease received his name in honor of his work.
(Continued)
Huntington’s disease is hereditary.
The faulty gene that causes Huntington's disease is
found on chromosome number 4. A normal copy of
the gene produces huntingtin, a protein. The faulty
gene is larger than it should be and produces a larger
form of huntingtin. Some of our brain cells are
sensitive to the larger form of huntingtin - it
undermines their function and eventually destroys
them.
(Continued)
A person with the Huntington's gene has one
good copy of the gene and one faulty copy of
the gene. His/her child will inherit either the
good copy or the faulty one. The child who
inherits the good copy will not develop
Huntington's disease, while the child who
inherits the faulty copy will. The child has a
50% chance of inheriting the faulty gene. If the
child inherits the faulty gene, each of his/her
children will have a 50% chance of inheriting
the faulty gene. Huntington's disease is inherited
in an autosomal dominant pattern. This means
that everyone who inherits the faulty gene will
eventually get the disease.So this disease can
be passed on to future generations.
PHENOTYPIC (PHYSICAL) EFFECTS OF HD
 Head
shifting to look around instead of just
moving the eyes.
 Speech impairment
 Uncontrolled movements
 Sudden jerks
 Trembling
 inability to regulate the speed or force of
movements
 sustained abnormal postures
What type of mutation is HD?
HD is caused by a mutation in a gene on chromosome
4. So it is a gene mutation.
 A gene mutation falls into the categories of mutations
by: Frameshift mutations or base pair substitutions.
Chromosomal mutations are mutations that result in
the whole addition, loss or inversion of the
chromosome.


Huntington's disease is caused by a frameshift
mutation due to the addition of extra nucleotides. The
mutant huntingtin -gene that codes for huntington's
disease is located on chromosome 4 which contains
more than 36 glutamine amino acids which should
normally only contain less than 36.
Healthy gene Vs. HD gene
Normal
sequence
Abnormal expanded sequence
• The abnormal expanded sequence is called a trinucleotide repeat.

During pregnancy a woman can find out if her baby
will have the disease with two tests: taking a sample
of fluid from around the fetus (amniocentesis), or by
taking a sample of fetal cells from the placenta
(chorionic villus sampling (CVS)).
How is HD treated?
There is no cure for Huntington’s disease,
Treatments do not slow the progression of
the disease, but they can help make the
patient more comfortable. Medications
ease feelings of depression and anxiety;
others control involuntary movements.
Unfortunately, after the symptoms start,
the individual only has about 8-10 years to
live.
3-7 people out of 100,000 have HD in Europe.
 1 person out of 30,000 in America
 150,000 other people are at risk
 HD is less common in Asians and AfricanAmericans.

Extra: Video
BIBLIOGRAPHY
"Huntington's Disease History." News Medical. N.p., n.d. Web. 18 Nov. 2012.
<http://www.medicalnewstoday.com/articles/159552.php>. Huntington's
Disease History
What Is The History Of Huntington's Disease (HD)?" Huntingtons. N.p., n.d.
Web. 18 Nov. 2012. <http://www.huntingtonsnsw.org.au/information/hdfacts/history>. History of Huntington's Disease
"What Is Huntington's Disease? What Causes Huntington's Disease?"
Medical News Today. N.p., n.d. Web. 18 Nov. 2012.
<http://www.medicalnewstoday.com/articles/159552.php>. Information on
Huntington's
"Huntington's Disease." Learn Genetics. N.p., n.d. Web. 18 Nov. 2012.
<http://learn.genetics.utah.edu/content/disorders/whataregd/hunt/>. Info
on HD