Types of brain disorders
Huntington's disease is a neurodegenerative
genetic disorder that affects muscle coordination and leads to
cognitive decline and dementia.
Huntington's disease (HD) is the most common
genetic cause of abnormal involuntary writhing movements called
chorea (the disease used to be called Huntington's chorea). It is
much more common in people of Western European descent than in
those of Asian or African ancestry, and usually becomes
noticeable in middle age.
Cause of Huntington's
The disease is caused by a mutation on either of an individual's
two copies of a gene called Huntingtin. This means any child of an
affected parent has a 50% risk of inheriting the disease. In the
rare situations where both parents have an affected copy, the risk
increases to 75%, and when either parent has two affected copies,
the risk is 100% - all children will be affected.
The Huntingtin gene normally provides the genetic
information for a protein that is also called "Huntingtin". The
mutation of the Huntingtin gene codes for a different form of the
protein, whose presence results in gradual damage to specific areas
of the brain. The exact way this happens is not fully
Symptoms of Huntington's
Physical symptoms can begin at any age but it's
mostly commonly between 35 and 44 years of age. About six percent
of cases start before the age of 21 years.
Symptoms vary between individuals, but
the earliest symptoms are a general lack of coordination and an
unsteady gait. As the disease advances, uncoordinated, jerky body
movements become more apparent, along with a decline in mental
abilities and behavioural and psychiatric problems. Physical
abilities are gradually impeded until coordinated movement becomes
Mental abilities generally decline into
dementia. Complications such as pneumonia, heart disease, and
physical injury from falls reduce life expectancy to around twenty
years after symptoms begin. There is no cure, and full-time care is
required in the later stages of the disease. Emerging treatments
can relieve some of its symptoms.
for Huntington's disease
Genetic testing can be performed at any stage
of development, even before the onset of symptoms. This fact raises
several ethical debates:
- what age is considered mature enough for someone to
- should parents have the right to have their children
- managing confidentiality and disclosure of test results.
Genetic counseling has developed to inform and
aid individuals considering genetic testing, and has become a model
for other genetically dominant diseases.
Research into Huntington's
Self-help support organizations, first founded
in the 1960s and increasing in number, have been working to
increase public awareness, to provide support for individuals and
their families, and to promote research. The Hereditary Disease
Foundation, a research group born out of the first support
organization, was instrumental in finding the gene in 1993.
Since that time, many new research discoveries
have been made and understanding of the disease is improving.
Current research directions include determining the exact mechanism
of the disease, improving animal models to expedite research,
clinical trials of pharmaceuticals to treat symptoms or slow the
progression of the disease, and studying procedures such as stem
cell therapy with the goal of repairing damage caused by the
References and further information
This information has been adapted from pages on Wikipedia
at en.wikipedia.org under the GNU
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