Essay, Research Paper: Huntington's Disease

The condition Huntington's Disease got its name because it was
first described by George Huntington, a physician in New York, in 1872.
It use to be commonly known as Huntington's Chorea - chorea being the
Greek word for dancing and describing the strange movements of the
sufferer. Most people now refer to it as Huntington's Disease or HD for
short. The illness probably occurs all over the world, though it has not
been thoroughly researched in many places, particularly in
underdeveloped countries.

The illness begins gradually, usually in one or the other following
ways: by a change in usual behavior, for example, depression,
moodiness, unreasonable outbursts of anger out of character for the
individual, or by unusual jerky, fidgety movements and perhaps
unsteadiness of the hands or feet causing falls and a tendency to be
clumsy. These are early signs. They are mild and increase so slowly that
they may go unnoticed and it is only much later, when looking back,
that relatives realize all has not been well for some years.

These changes are thought to come about because of a disturbance
of one of the chemical substances concerned in normal functioning of
the brain though it is not known exactly which chemical is involved.
Over the years the illness goes on getting more severe, though the rate
at which it progresses varies from individual to individual. However,
once it has started, it goes steadily on. The ungainly jerky movements,
over which the sufferer has no control, increase, causing falls and
making walking difficult. Speech usually becomes slurred and
swallowing difficult. Some, though not all, will at times become
confused and forgetful, at other times angry and unreasonable and
possibly violent.

Alternatively, some people become quite passive. But the illness
has its ups and downs and some days the ungainly movements and
irritability are less. This changing state is confusing and frustrating for
both sufferers and their families. At present there is no known cure,
though medicine may lessen the jerky movements, and sympatheticand
understanding care can help to keep the sufferer less agitated and so less
liable to unreasonable behavior. Ultimately, it may become too difficult
to care for the sufferer at home.

The illness usually lasts 15-20 years, although it may be
considerably longer. Death is often from pneumonia because sufferers
cannot cough well enough to clear the chest if they have infections. The
most common age of onset of the illness is between the age of 30 and
50 years, although it can manifest itself at almost any age. Both men
and women are affected and it is estimated that perhaps 6,000 people
now have the illness in the United Kingdom. HD is hereditary and runs
in families in a way that is well understood. It is called a dominant
disorder.

It is known for certain that HD is a dominant disorder and that the
abnormal gene needs to be present on only one member of a gene pair for
the individual to develop the disorder. This means that each time an
individual who has the gene for HD (though he may not yet have signs
of it) has a child, there is a 1 in 2 chance that the child will inherit the
HD gene. There is also a 1 in 2 chance that the child will inherit the
normal gene. Everyone who inherits the HD gene will eventually develop
the disorder unless he or she dies from some other cause before the
signs appear

Because they are like their affected parent in, say, stature or skin
or eye color, some people fear they may also have inherited the HD gene
too. Physical or temperamental likeness to an affected parent does not
imply that the child has also inherited the HD gene; nor does it change
the 1 in 2 risk. It can only be said that, on average, half the children of a
sufferer will inherit the gene. This does not mean, for example, that
precisely 2 out of 4 or 3 out of 6 children in a family will inherit it, but
that every child has a 50/50 chance of getting it. Some families are
lucky and perhaps 4 out of 4 children will escape; other families, less
fortunate, demonstrate that 4 out of 4 can be affected; but the chance
for any other child remains 1 in 2. When large numbers of families
containing many children are studied, the proportion of 1 in 2 (or
50/50) affected is regularly seen.

For some time researchers have known that the gene for HD was
near the end of chromosome 4. Since the discovery of the HD gene in
March 1993, a new predicting test has been developed. This can
identify the carriers of the faulty gene before they develop the illness.
After a number of counseling sessions at a genetic clinic, blood samples
are taken from the person who wishes to be tested. The DNA which is
extracted from the blood is then analyzed in a special laboratory.
Occasionally the result falls in a 'gray area' where it is still uncertain
whether the person will develop HD or not. Even when the test does
show that someone has the faulty gene, it still does not show the age at
which the disease will start to develop

There is a different type of test which can be carried out on a
fetus. This test analyses DNA from several family members using
markers linked to the gene. It shows whether the baby is at low risk of
inheriting the faulty gene or at the same risk as the parent who is at risk
but so far unaffected.

All over the world research is going on into Huntington's Disease.
One day, sooner or later, the cause will be better understood and a
treatment found. This may come in the lifetime of young people who
still have to face an uncertain future. We all long for the day when the
scourge of this illness, like many others, will be removed from us. In the
meantime, families are joining together worldwide to promote better
treatment and understanding of those who suffer and to make their
needs known.

The International Huntington's Association crosses all boundaries
of race and language and links people in a common cause, to face with
courage what cannot be changed and to change what it is in our power
to change, working together towards greater knowledge and better
services, and above all creating the sense of fellowship that overcomes
fear and isolation. Scientists have come a long way in the past few years
and there is hope for the future.

Works Cited/Consulted


Bram, Leon L. and Norma Dickey. Funk & Wagnalls New
Encyclopedia. New York. Rand McNally 1988

Microsoft Corporation. Microsoft Bookshelf 98.
Seattle. Microsoft 1998

http://www.grolieronline.com/hd/info

Fadiman, Clifton and Daniel Boorstin. The Treasury
of the Encyclopedia Britannica. New York.
Penguin Group 1992
















Genetic Disorders:
Huntington's
Disease









Danny Dore
Period 6
12/14/98