Huntington's disease (also known as Huntington disease) is a progressive and incurable brain condition. However, a potential treatment called RG6042 may stop or even reverse the progression of the disease.
What is Huntington's disease?
In 1872 a 22-year-old doctor named George Huntington described a disease he called "progressive chorea," referring to involuntary dance-like movements, or chorea, that are caused by the condition. Huntington's disease is now recognized as a hereditary condition. It requires only the transmission of a single dominant gene from one parent who has the condition to cause symptoms in adulthood that inevitably lead to death.
What are the symptoms of Huntington's disease?
The gene that causes Huntington's disease is present from birth, but it usually does not cause symptoms before age 30. In one-half to two-thirds of cases, the initial symptoms are related to movement. There can be a general tendency to fidgetiness. Over time, the smaller "fidgety" movements can led to ballism, which is flailing or ballistic movements of the arms and legs.
As debilitating as the "chorea" of Huntington's disease can be, the next stage of the condition is more debilitating. After a few years, people who have Huntington's develop Parkinson's-like rigidity replacing the flailing movements. In this stage, there can be frozen joints and difficulty swallowing. Still later in the disease, there is clonus, circular motions of the limbs, and abnormal reflex responses in the feet.
Dementia is part of Huntington's disease, but not everyone who has Huntington's loses cognitive function at the same rate. The earlier the symptoms of the disease appear, the later dementia will develop. In one-third to one-half of cases, psychiatric symptoms appear before abnormal movements.
Huntington's dementia is also progressive:
- Sometimes a schizophrenia-like illness precedes motion disorders by several years. Up to 12 percent of people who hav Huntington's develop mania.
- Early symptoms of dementia seem to come and go. Someone with Huntington's may make many embarrassing comments. They may lose interest in bathing and washing after using the toilet. They may let dirt and trash accumulate in the home. Apathy and irritability are not unusual. Neither is sexual hyperactivity. At this stage, the Huntington's patient is still able to recruit partners for sex and to carry out the act, but may not think through consequences. Loss of inhibition may be sporadic. There can be long periods of normal behavior with unpredictable incidents of loss of self-control. Family members who have different amounts of contact with their relative who has Huntington's disease may disagree about the severity of these symptoms.
- Apathy is generally worse in men than in women who have the disease. Taking benzodiazipine tranquilizers mokes apathy worse.
- As the disease progresses, there often is a loss of fluency in speech, reading, and writing. The attention span becomes shorter. Judgments are "off.' it is usually necessary to name powers of attorney or conservators to protect patients from themselves.
- in the later stages of Huntington's dementia, there is a marked loss of "outgoing" language. People who have Huntington's may not be able to recall words, but they often retain the ability to understand them. The latest stages of the disease are usually complicated by severe weight loss and loss of bowel and bladder control.
There is a wide variety of psychiatric conditions in Huntington's dementia. Psychiatric conditions affect up to 73 percent of people who have the disease, Depression is common. Alcoholism may occur in people who are mortified by the things they did under the influence as a result of the disease, but who retain insight.
About 6 percent of people who have Huntington's disease commit suicide. Because the condition is almost always genetic, they have witnessed one or both parents or one or more grandparents going through the disease. Suicide prevention is a necessary part of care.
Are there any medications for Huntington's disease?
There is only one FDA-approved medication for Huntington's disease, tetrabenazine, which is marketed under the trade name Xenazine. This drug is prescribed for the abnormal movements caused by the disease. it has no effect on dementia. Doctors use some of the same medications prescribed in other disorders for psychotic disorders (delusions, hallucinations, and paranoia), and to deal with wandering, agitation, and combativeness.
There is currently one medication in clinical trials that may stop or reverse Huntington's disease sponsored by Roche Pharmaceuticals (also known as Genentech). This investigational medication is called RG6042 (formerly known as IONIS-HTTRx). In the first clinical trials, levels of the toxic huntingtin protein were reduced by an average of 60 percent in spinal fluid. Researchers believe this corresponds to a 55 to 85 percent reduction of the protein in the cortex, the outer layers of the brain.
Even if the medication is found to be effective and fast-tracked to be made available to the public in the US, UK, Canada, and the EU in 2020 or 2021, there is a difficult decision to be made before using it. RG6042 is most likely to be effective in the early stages of the disease. To know whether you need to disease, you need to have the genetic testing that tells you whether you have it. Currently, only 7 to 10 percent of people who have Huntington's have genetic testing before they have symptoms to find out whether they will develop the disease later. To get the treatment that may stop the disease, it will be necessary to take the brave step to confront it.