What is Huntington's Disease and Treatments
1. Huntington's Disease Facts
Huntington's disease
is a neurodegenerative disorder caused by a genetic mutation in the HD gene.
Symptoms begin between 30 and 50 years old, and the course of the illness lasts
until death. There is no cure for HD; however, symptoms can be managed medically,
including medication, physical therapy, speech therapy, and diet modifications.
2. Huntington's
Disease Causes & Risk Factors
The main cause of
Huntington’s disease is a faulty gene called HTT. Without HTT, people cannot
make the protein huntingtin. Huntingtin helps cells communicate information
throughout the body and regulates nerve impulses in the brain. When the HTT
gene becomes defective, the huntingtin protein becomes abnormal and fails to
function properly, causing damage to the nerves. In time, these damaged nerves
result in movement disorders, cognitive changes, and mood problems.
A person who inherits
two copies of the mutated HTT gene has a 50% chance of developing the disease.
A person may develop HD even if they inherit only one copy of the mutant HTT
gene, but their risk increases with each additional copy. If both parents have
the same version of the HTT gene, the child has a 25% chance of having the
disease.
Other factors
contribute to a person’s likelihood of getting HD. People with a family history
of the disease are at higher risk. Age at onset also contributes to risks of
getting the disease. Having children before age 35 doubles a woman’s chances of
having HD compared to women who delay child-bearing. And men are at double the
risk of women to develop HD.
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| What is Huntington's Disease and Treatments |
3. Huntington's
Disease Symptoms
Huntington's patients
often experience early symptoms similar to those observed in Alzheimer’s
disease. These initial symptoms occur gradually and include memory loss, poor
judgment, difficulty with language and writing, depression, and apathy. Over
time, patients lose coordination, tremors, balance difficulties, slurred
speech, and muscle rigidity. As the disease progresses, patients become blind,
immobile, and bedridden. Most people die within 10 to 20 years after the start
of symptoms.
4. Huntington's
Disease Treatments & Care
There is currently no
cure for Huntington’s disease. Treatment focuses on managing symptoms and
slowing progression of symptoms. Doctors treat individuals following standard
protocols approved by the Food and Drug Administration. Medications prescribed
include acetazolamide, valproate sodium, naltrexone, amantadine, gabapentin,
memantine hydrochloride, low molecular weight heparin, antiepileptic drugs,
tetrabenazine, and others. Physical therapies, occupational therapy, and speech
therapy may also help manage symptoms.
For individuals who
do not respond well to medications or wish to avoid long-term use, research
shows that transcranial magnetic stimulation (an electrical brain wave
treatment) may slow progression of symptoms. However, the effectiveness of this
type of treatment remains controversial.
5. Huntington's
Disease Support Groups
Support groups exist
for families affected by Huntington's disease. You can find a list of local
Huntington's disease support group in our directory under resources.
What is Huntington's Disease and Treatments
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| What is Huntington's Disease and Treatments |
1. Huntingtin protein
The huntingtin
protein is a protein that occurs naturally in the body. In people with
Huntington's disease, the function of this protein seems to cause abnormal
changes in nerve cells. These neurons eventually die off leading to symptoms of
the disease. So far, no cure has been discovered for Huntington's disease, but
scientists continue to study potential therapies. One way to help slow down the
degeneration of these nerve cells is with a drug called Deprenyl (Parnate).
This drug reduces the accumulation of mutant huntingtin protein inside the
nerve cells.
2. Enzyme replacement
therapy
Enzyme replacement
therapy uses synthetic enzymes that are similar to those produced normally by
the human body. Scientists have tried using synthetic versions of the enzyme
hyaluronidase. If injected directly into the brain, they could act as a type of
glue that would attach to clumps of mutated huntingtin proteins and prevent
them from forming. Scientists at University College London were able to show
that the injection of hyaluronidase was effective in preventing disease
progression in mice. Researchers hope that these results may help lead to a
treatment regimen for humans in the future.
3. Chaperone therapy
Researchers are
currently studying chaperones, anti-inflammatories that help break up the
clumps of mutant huntingtin proteins. One drug that researchers use to treat
Alzheimer's disease is donepezil (Aricept); however, its effects on inhibiting
the formation of clumps of mutant huntingin proteins have not yet been studied.
4. RNA interference
therapy
RNA interference
therapy involves introducing certain genes into stem cells. These stem cells
then differentiate into nerve cells that produce the necessary proteins needed
to repair the damage caused by the mutated huntingtin protein.
5. Glycine
transporter inhibitor therapy
Inhibitors of glycine
transporters reduce excess levels of glutamate while promoting the release of
neurotransmitters. By reducing the amount of excitatory glutamate released in
the brain, there is less likelihood of neuronal injury and death. A drug called
Sarcosine (N-Acetyl sarcosine) works as a glycine transporter inhibitor. It is
administered intravenously and has shown promise in reducing motor deficits in
mouse models of Huntington's disease.
6. Apoptosis
inhibitors
Apoptosis inhibitors
work by inhibiting the apoptotic process, thereby stopping the destruction of
nerve cells. Studies have shown that several different chemicals can inhibit
apoptosis. One example is the drug Dimebon (Valdoxan), which inhibits the
mitochondrial release of cytochrome C and blocks apoptotic signaling cascades.
Dimebon is now being tested in clinical trials for its effectiveness in
treating patients with Huntington's disease.
7. Nerve growth
factor therapy
Scientists believe
that nerve growth factor (NGF) may play a role in maintaining the survival of
embryonic neural progenitor cells. NGF, which is present in the central nervous
system, helps maintain the viability of damaged neurons. It promotes the growth
of nerve fibers and improves neurological functioning. An experiment performed
in vitro showed that NGF significantly increased the number of neuron cells.
Another method scientists are exploring for treating Huntington's disease is to
inject NGF directly into the brains of patients with the disease.