Huntington ‘s disease is an incurable, hereditary brain condition. This is a debilitating disease that causes brain cells, or neurons, to become damaged.
This occurs when a defective gene triggers the accumulation of harmful proteins within the brain.
Huntington’s disease ( HD) affects one person in every 10,000 people, or about 30,000 people in the USA. About 150,000 individuals or more are at risk of having the condition.
The first signs usually show up between the ages of 30 and 50 years.
Important facts about Huntington’s disease
- Huntington’s disease (HD) is an inherited disease that attacks nerve cells gradually over time.
- The disease happens when a faulty gene makes an abnormal version of the huntingtin protein.
- Early symptoms may include mood swings, clumsiness, and unusual behavior.
- During the later stages of the disease, choking becomes a major concern.
- There is currently no cure, but medications may help relieve symptoms.
What is Huntington’s?
Neurological disorder is Huntington’s disease (HD). This is an inherited disorder that arises because of defective genes. Toxic proteins accumulate in the brain and cause damage which leads to symptoms of neurology.
It influences movement, actions, and reasoning, as parts of the brain deteriorate. It becomes harder to walk, think, reason, swallow, and talk. The person would ultimately need the full-time treatment. Typically the consequences are fatal.
Currently there is no cure, but symptom treatment can help.
Symptoms
It is most likely that signs and symptoms will appear between the ages of 30 and 50 but they can occur at any age. We appear to get worse in 10 to 20 years.
The Huntington disease or its causes are inevitably fatal.
The symptoms of HD may sound like getting amyotrophic lateral sclerosis (ALS), Parkinson’s and Alzheimer’s all in one, according to the Huntington ‘s Disease Society of America (HDSA).
The key symptoms include:
- personality changes, mood swings, and depression
- problems with memory and judgment
- unsteady walk and uncontrollable movements
- difficulty speaking and swallowing, and weight loss
How the signs and symptoms evolve can vary from individual to individual. Depression occurs in some people before affecting the motor skills. Early signs of mood swings and unusual behavior are common.
Early signs and symptoms
Early signs can not be known if there has not been HD in the family before. It can take a long time to reach a diagnosis.
Initial signs and symptoms include:
- slight uncontrollable movements
- small changes in coordination and clumsiness
- stumbling
- slight signs of mood and emotional change
- lack of focus, slight concentration problems, and difficulty functioning, for example, at work
- lapses in short-term memory
- depression
- irritability
The person may lose motivation and concentration, and may appear lethargic and lack initiative.
Some potential symptoms of HD may include stumbling, dropping items and missing the names of people. Yet most people do so from time to time.
The middle and later stages
Symptoms become more serious over time.
Those include physical changes, loss of regulation of motion and changes in emotion and cognition.
Physical changes
The person may experience:
- difficulty speaking, including looking for words and slurring
- weight loss, leading to weakness
- difficulty eating and swallowing, as the muscles in the mouth and diaphragm may not work properly
- risk of choking, especially in the later stages
- uncontrollable movements
There may be uncontrollable body movements, including:
- uncontrollable movements of the face
- jerking of parts of the face and the head
- flicking or fidgety movements of the arms, legs, and body
- lurching and stumbling
As HD progresses, uncontrollable movements occur more often and with more severity, typically. Eventually they may become slower as the muscles become more rigid.
Emotional changes
These may alternate rather than occurring consistently.
They include:
- aggression
- anger
- antisocial behavior
- apathy
- depression
- excitement
- frustration
- lack of emotion becomes more apparent
- moodiness
- stubbornness
- cognitive changes
There may be:
- a loss of initiative
- a loss of organizational skills
- disorientation
- difficulty focusing
- problems with multitasking
The later stage
Ultimately the person won’t be able to walk or speak anymore, so they will need full nursing.
However, they will probably know most of what is being said and will be aware of friends and family members.
Complications
The failure to do things that used to be easy can lead to depression and anger.
Weight loss can worsen the symptoms and weaken the immune system of patients, making them more vulnerable to infections and other complications.
HD itself is usually not fatal, but it can be choking, pneumonia, or some other infection.
It is important to adjust the diet of the patient throughout all stages to ensure adequate intake of the food.
Causes
HD is caused by a faulty gene (mhTT) on chromosome number 4.
A normal copy of the gene produces a protein called huntingtin. The defective gene is broader than it should be. It contributes to excessive cytosine, adenine, and guanine production (CAG), the building blocks of DNA. Usually CAG repeats 10 to 35 times but repeats 36 to 120 times in HD. If it repeats 40 times or more it is likely to have symptoms.
This change results in a more extensive form of huntingtin. It is poisonous, and is causing damage to brain cells as it accumulates in the brain.
Some brain cells are responsive to the larger type of huntingtin, particularly movement, thought and memory-related ones. It undermines their role and eventually wrecks them. Scientists aren’t exactly sure how that happens.
How is it passed on?
HD is a disorder known as autosomal dominant. This means that only one copy of the defective gene is required to produce the disease, inherited either from the mother or the father.
A person with the gene has one successful gene copy, and a bad gene copy. Any offspring inherit either the good or the faulty copy. The child inheriting the good copy won’t develop an HD. The child inheriting a defective copy will.
Growing child has a chance of inheriting the defective gene by 50 percent. When they inherit the defective gene, they each have a 50 percent chance of inheriting it. HD will affect generations.
A person who does not inherit the defective gene will not acquire HD and can not pass it on to his or her kids. A child inheriting the faulty gene will develop HD if it reaches age when symptoms are likely to occur.
Approximately 10 percent of HD cases start before age 20. So named juvenile HD (JHD).
The signs are distinctive, and may include weakness of the legs, tremors and learning loss.
About 30 and 50% of JHD sufferers had seizures.
Treatment
Apparently HD is incurable. There is no medication able to reverse or delay the progression.
Nevertheless, medicine and therapy can relieve some of the symptoms.
Medications
The Food and Drug Administration ( FDA) recommends tetrabenazine (Xenazine) for the treatment of HD-associated jerky, repetitive movements, or chorea.
Side effects include depression and thoughts or actions which are suicidal.
Symptoms include:
- feeling sad and having crying spells
- losing interest in friends and previously enjoyable activities
- sleeping more or less than usual and feeling tired
- feeling guilty or unimportant
- feeling more irritable, angry, or anxious than before
- eating less than usual, possibly with weight loss
- having difficulty focusing
- thinking about harming oneself or ending one’s life
Each of those symptoms or other changes in mood should be reported to the doctor immediately.
Anyone who has a diagnosis of depression should not use tretrabenazine particularly with suicidal thoughts.
Drugs for movement control, outbursts, and hallucinations can include:
- clonazepam (Klonopin)
- haloperidol
- clozapine (Clorazil)
These drugs may cause sedation, as well as stiffness and rigidity.
For depression and some obsessive-compulsive features that can appear with HD, the doctor may prescribe:
- fluoxetine (Prozac, Sarafem)
- sertraline (Zoloft)
- nortriptyline (Pamelor)
With intense emotions and mood swings, lithium can help.
Speech therapy
Speech therapy can help patients find ways to convey terms and phrases, and more effectively connect.
An occupational and physical therapy
A physical therapist may help improve muscle strength and endurance, resulting in improved balance and decreasing risk.
An occupational therapist may help the patient develop techniques to deal with issues with attention and memory, and make the home safer.
Diagnosis
The doctor will examine the patient and ask about family history and medical history, and symptoms such as recent changes in emotion.
If they suspect HD the patient will be referred to a neurologist.
Imaging scans, including a CT or MRI scan, are often used to detect changes in the brain structure of the patient, and to rule out certain conditions.
Genetic testing may be recommended to confirm a diagnosis.
Outlook
HD has a significant emotional , mental, social , and economic effect on individual and family lives. A person would usually live for 15 to 20 years after diagnosis, but the average varies between 10 and 30 years.
A person with JHD is likely to live about 10 years. This form progresses more quickly.
The cause of death, such as pneumonia or choking, is often a complication.
Although there is no cure at the moment, some therapies can help people manage the condition and improve the quality of life.
Hope for the future?
Scientists hope the gene therapy will find a cure to this disease in the future. Scientists have been searching for ways to cure, delay or avoid HD using gene therapy.
One promising solution is to use molecules known as synthetic small interfering RNAs (siRNAs) to inhibit the production of protein from the defective gene. This would avoid the poisonous protein Huntingtin from accumulating and causing symptoms.
However, the remaining challenge is how to deliver the siRNAs to the correct brain cells, so they can be successful.
In 2017, Emory University scientists suggested that CRISPR / Cas9 techniques, which require “cutting and pasting” DNA, could help to prevent HD in future.
They observed “significant improvements” after 3 weeks, when the researchers engineered the faulty gene in mice. Many traces of the destructive protein had gone away, and the nerve cells showed signs of themselves healing.
Nonetheless, much more research is needed before that can be applied to humans.
Organizations like HDSA are providing support for people with HD and their families.
Genetic testing
In 1993 Genetic HD testing became feasible. Anyone with an HD family history may ask their doctor about genetic testing to see if they are carrying the defective gene or not.
Many people prefer to find out whether they have the gene, and whether they are likely to develop symptoms, while others choose not to ask. A genetic counselor can assist in the decision making process.
HD, genetics, and pregnancy
If a couple wishes to have a child, and one parent has the defective gene, in-vitro fertilization (IVF) treatment may be required. The embryo is then genetically tested in a laboratory, and is inserted into the woman only if the defective gene is not present.
Genetic testing can also be done during pregnancy, if an HD family history is present. It can be achieved at 10 to 11 weeks with chorionic villus sample (CVS), or at 14 to 18 weeks with an amniocentesis.
