What is Huntington’s Disease (HD)?
Huntington’s Disease: a devastating, hereditary, degenerative brain disorder for which there is, at present, no effective treatment or cure. HD slowly diminishes the affected individual’s ability to walk, talk and reason. Eventually, the person with HD becomes totally dependent upon others for his or her care. Huntington’s Disease profoundly affects the lives of entire families — emotionally, socially and economically.
Named for Dr. George Huntington, who first described this hereditary disorder in 1872, HD is now recognized as one of the more common genetic disorders. More than a quarter of a million Americans have HD or are “at risk” of inheriting the disease from an affected parent. HD affects as many people as Hemophilia, Cystic Fibrosis or muscular dystrophy.
Early symptoms of Huntington’s Disease may affect cognitive ability or mobility and include depression, mood swings, forgetfulness, clumsiness, involuntary twitching and lack of coordination. As the disease progresses, concentration and short-term memory diminish and involuntary movements of the head, trunk and limbs increase. Walking, speaking and swallowing abilities deteriorate. Eventually the person is unable to care for him or herself. Death follows from complications such as choking, infection or heart failure.
HD typically begins in mid-life, between the ages of 30 and 50, though onset may occur as early as the age of 2. Children who develop the juvenile form of the disease rarely live to adulthood.
HD affects males and females equally and crosses all ethnic and racial boundaries. Each child of a person with HD has a 50/50 chance of inheriting the fatal gene. Everyone who carries the gene will develop the disease. In 1993, the HD gene was isolated and a direct genetic test developed which can accurately determine whether a person carries the HD gene. The test cannot predict when symptoms will begin. However, in the absence of a cure, some individuals “at risk” elect not to take the test.
Since the discovery of the gene that causes HD, scientific research has accelerated and much has been added to our understanding of Huntington’s Disease and its effects upon different individuals. By continuing to increase investment in both clinical and basic HD research each year, breakthroughs in treatment – and a cure can be forthcoming.
What are HD symptoms?
Symptoms usually evolve slowly vary from person to person, even within the same family. Some individuals may be affected first cognitively (depression, forgetfulness, impaired judgment). Others suffer with motor skill impairment (dystonia or involuntary movements, unsteady gait). Eventually, every person afflicted by HD requires full-time care.
Domains affected include: cognitive, motor and behavioral. Members of the same family may exhibit different symptoms. Some can show mild involuntary movements (chorea) and have more emotional/behavioral symptoms of HD or can have less emotional/behavioral symptoms with more difficulty with involuntary movements.
Some HD Symptoms:
Involuntary movements (chorea, dystonia)
Difficulties with speech, swallowing, balance, walking
Problems with short-term memory, organizing, coping, concentrating
Can you predict when you will get the disease?
You must have inherited the gene to get the disease.
Thought there may be some correlation between the number of times the CAG is repeated and the age of onset, it is impossible to know exactly when the disease will begin to manifest itself. The higher the CAG repeat, the more likely HD will strike at a younger age. Most individuals affected by HD exhibit symptoms between the ages of 30 to 50 years of age. In rare cases, children as young as two and individuals as old as 80 have exhibited symptoms of HD.
How many are affected by HD?
One out of every 10,000 Americans has HD. Yet the devastating effects of HD touch many more. HD does not skip generations.
Each child of a parent with HD has a 50/50 chance of inheriting the gene that causes HD.
If a child does not inherit the gene, he or she cannot pass it on. If the child does inherit the gene, he or she can pass it on and will develop the disease if that child lives long enough. There areapproximately 200,000 Americans “at-risk” of developing the disease.
How long do you live after HD symptoms begin?
The average lifespan after onset of HD is 10-20 years. The younger the age of onset, the more rapid the progression of the disease.
What is the prognosis for those with Huntington’s Disease?
At this time, there is no way to stop or reverse the course of HD. There is no treatment to halt the progression, which leads to death after ten to twenty-five years. However, now that the HD gene has been located, investigators are continuing to study the HD gene with an eye toward understanding how it causes disease in the human body.
What is the cause of death for most HD patients?
Most people with HD do not die as a direct result of HD but rather from medical problems that arise (infections, choking and pneumonia) from the effects of HD on the body.
Is there an effective treatment or cure at this time?
Research has yet to find a means of curing or even slowing the deadly progression of HD although some medications can relieve some of the symptoms in certain individuals.
What progress has been made in HD research?
Since 1993 when the gene that causes HD was discovered, much has been added to the understanding of the disease. Research efforts are currently exploring many new avenues and approaches including focus on way to delay onset of HD, development of effective therapies that may slow the progression of HD and ultimately, a cure for the disease.
What social and legal issues do people with HD face?
Those affected by HD often face discrimination both on the job and from their health insurance carrier. While genetic discrimination in the workplace and from health insurance carriers has been banned in the federal government positions, few other employees enjoy these same protections.
Individuals who suffer from the movement disorder associated with HD are often accused of being intoxicated because of slurred speech or an uneven gait. For those in which the first stage of the disease may show itself either mentally or emotionally, these “hidden” disabilities can be difficult for people to understand. Those with HD are often blamed for behaviors they cannot control.
What is genetic testing and what does it involve?
This is a process where blood is taken and analyzed to determine if the gene for HD is present. The result enables those who are “at risk” to learn whether they carry the gene or not. Few of those people “at risk” of HD opt to have the test performed given the fact that there are few therapeutic options available effective in combating the effects of HD.
Anyone considering genetic testing for HD is advised to work with a genetic testing center that follows HDSA’s genetic testing guidelines that include both pre-and post- test counseling. Only those over the age of 18 may be testing for HD unless they are exhibiting symptoms of the disorder.
Genetic testing can also be utilized to confirm a clinical diagnosis of HD. The test cannot provide an age of onset. It can confirm only that an individual has or does not have the HD gene.
Where can I go for more information about HD?
Contact an HDSA chapter near you or your nearest HDSA Center of Excellence. You can also call the HDSA National Office at 800 345-HDSA (4372) or visit the HDSA website www.hdsa.org