Huntington’s disease (HD) is a rare neurodegenerative disease. It progressively affects the patient’s mobility and cognitive function. Unfortunately, a cure has yet to be discovered and the condition is always fatal.
The age of onset of HD varies by the patient. Symptoms can begin when the individual is as young as age 20 or as old as 80, however most patients begin experiencing symptoms during middle age. After the onset of symptoms, patients generally have 10 to 25 years to live.
All individuals who have the HD mutation will develop the illness. There is currently no way to prevent its onset. However, there are medicines available which are effective at treating symptoms. Additionally, researchers are working to on developing new therapies which could potentially alter the course of HD such as gene splicing, which works to lower the level of abnormal proteins produced by the mutated gene.
While there is no way to prevent HD (yet), there is a test to inform patients whether or not they have the gene. That said, many patients choose not to receive this test.
To Know or Not to Know
There are over 200,000 individuals at risk for developing Huntington’s disease in the United States but, its estimated that around 90% of these people choose not to know whether or not they will develop the disease, even though there is a test which can inform them. For these at risk individuals, the chance of inheriting the disease is 50%.
A recent study set out to understand why. There have been many studies done to understand why people choose to conduct the test, but there’s limited data on why individuals opt out.
Why does each individual’s choice matter to science? There’s a few reasons. First, for clinical trials which are aiming to uncover treatments which may be effective for patients who haven’t yet developed any symptoms of disease, a genetic test for participants is necessary. Second, studies have shown that clinicians generally have fewer conversations with their patients who choose not to know whether or not they have the HD gene. This is an issue because regardless of their choice to test, these individuals may still benefit from the supportive counseling which is offered to those who decide to get the testing. Typically, it is not offered for this population.
The study’s lead investigator, Doctor Karen Anderson, who is a professor at Georgetown University, makes it clear that each individual choice needs to be respected and the same support needs to be provided for all.
The study, titled Prospective Huntington At-Risk Observational Study (PHAROS) took place between 1999 and 2008. There were 1,001 participants in total, all who were potential carriers of the HD gene mutation. All of these individuals had made the decision not to know their status.
The gene mutation that causes HD was discovered in 1993. The test that could detect this mutation became available soon after. It was kind of expected that most people would want to take the test to rid themselves of the uncertainty. However, since that time, only 10-15% of individuals at risk have made the decision to know. What is perhaps more surprising is that this percentage hasn’t varied much over the years.
This particular evaluation by Anderson came from a subset of 733 of these participants. All participants consented to receiving the gene analysis test for the study, with the knowledge that they would not be told the results.
The study found two primary reasons why people chose not to know. First, they knew there was no effective treatment or cure currently available. Second, they knew that once they found out they could never reverse that knowledge. Additionally, these participants didn’t believe that, within the next ten years, there would be a therapy that could prevent the onset of disease. That said, they were optimistic that there would be improved therapies for symptoms within that time period.
This study was published in Clinical Genetics.
Why It’s Important
For healthcare providers, it is helpful to understand why an individual is making the decision they are so that they can best guide them through their future options (for instance, clinical trials). They need to ensure they aren’t suggesting someone do a test when it wouldn’t be in their own self-interest. Some people may never want to be tested, and those choices need to be supported and respected.
For those who do want testing, its important to make sure that the individual is ready to cope with whatever the outcome may be. Things like financial planning, future care, and clinical trial participation are all important topics to discuss. It is the duty of the healthcare professional to make sure their patient receives the critical information they need that is best suited to them as an individual.
You can read more about this study and the choice to test here.