WeAreHD.org - The Social Support Network for People Living with Huntington's Disease

Nearly 25,000 Americans suffer from
Huntington’s disease, so they cannot control their own actions and are
unable to make their own decisions. The statistics for the disease, as
reported in an article in The New York Times, also show that
nearly 75,000 people carry the mutant gene responsible for the disease
and are largely unaware of having the disease until its symptoms start
showing up, which is usually around middle age. The symptoms of this
genetic disorder are due to the wasting of neurons, or loss of nerve
cells, in the brain.

The disease is named after the American physicist George Huntington,
who first described it in 1872. Sometimes, the disease is also called
Huntington’s chorea because in Greek, the word chorea means
“dance,” and dance describes the jerky, involuntary, and uncontrolled
movements that characterize the disease. The disease is a
neurodegenerative disease in which the cells of the brain and spinal
cord are lost. These cells have different functions that include
controlling movements, making decisions, and processing sensory
information.
Huntington’s disease is a genetic disorder caused by a mutation in the
Huntington gene. In this disorder, the length of the Huntington gene
exceeds its normal range.

The Huntington gene normally consists of a sequence with repeats of
multiple units of three bases — CAG. This is a trinucleotide repeat
representing the amino acid glutamine. The resultant chain with the
repeats is called a polyglutamine or polyQ tract. A chain with more
than 36 glutamines results in Huntington’s disease because, in this
case, the rate of decay of medium spiny neurons, which are cells in the
brain that are responsible for controlling body movements, increases.
If a person has a faulty gene for this disease, there is a 50 percent
chance that their offspring will have the defect as well. But, if the
offspring does not inherit the disease, it cannot be passed on to
future generations. Children rarely develop the symptoms of the
disease. When the symptoms do develop in young people, though, they
suffer severely and their symptoms progress very quickly. The disease
is classified as juvenile Huntington’s disease in this case.

The initial signs of Huntington’s disease are decreased cognitive
abilities and personality changes. People suffering may show signs of
depression or get irritated or angry. It may also become hard for them
to answer questions and make decisions. They may not remember important
information and may become forgetful. The patient is usually unaware of
the changes due to the disease and may notice them quite late, often
after family and friends become aware of these changes.
The physical signs of this genetic disorder include clumsiness, mild
balancing problems, and involuntary facial movements, like grimacing.
As the disease progresses, the whole body may exhibit sudden jerky,
involuntary movements with severe balancing problems. It becomes very
hard for the person to coordinate his or her movements and to shift his
or her gaze without moving the head. The suffering person may have
slurred speech and swallowing problems. Often, these physical problems
are accompanied by dementia.

The severity of the disease in young people can be explained by the
fact that their symptoms are similar to those of Parkinson’s disease
and include tremors, slow movements, and muscle rigidity. As described
on Mayoclinic.com, those who
acquire the disease very early in their lifetimes may even have
seizures. These symptoms develop slowly over a long period of time. The
degree of nerve waste, or nerve cell loss, determines the severity of
the symptoms. Usually, the patient succumbs to the disease 10 to 30
years after the first signs show up. But it may progress faster in
severe cases.

There is no satisfactory cure to stop or prevent Huntington’s
chorea, but some treatments help control the symptoms. Tranquilizers
and antipsychotic drugs help in controlling the involuntary movements,
any violent outbursts, and possible hallucinations, but these
medications may also result in side effects like additional stiffness
and rigidity or sedation. Speech and physical therapy may help control
the problems of impaired speech and keep muscles flexible and strong,
respectively. Occupational therapy may help the suffering person cope
with concentration and memory problems.

There is continuous research going on to find a treatment to slow
the progress of Huntington’s disease. According to an article on CNN.com,
the combination of certain cancer and AIDS drugs has resulted in the
halting of Huntington’s disease in a model system of fruit flies.
However, these drugs have not been tested on humans yet and it may be a
while before a conclusive therapy for this disease is devised.

LINK: http://thetartan.org/2009/4/27/scitech/healthtalk