HUNTINGTON’S DISEASE AND THE ETHICS OF PREDICTIVE TESTING
The Elephant in the Room
A conversation about Huntington’s disease minus mention of the ethical dilemmas posed by the illness is akin to ignoring the elephant in the room. The combination of the autosomal-dominant nature of HD—only one gene from one parent is required for offspring to inherit the illness—and the late onset of the disease presents issues unlike those found in other hereditary diseases.
Many individuals are unaware that they carry the HD gene until they experience their first symptoms in middle age. By that time, some have married and produced children. These offspring have a 50% chance of inheriting the disease. If they do, they will most likely be afflicted in middle age as well, and after they have had children of their own. This is the cycle researchers have worked tirelessly to disrupt.
Presymptomatic Testing
Since HD can be avoided only if carriers do not have children, a simple solution would seem to be to test people who have an HD member in their family for the HD gene before symptoms appear (presymptomatic testing). Such testing would enable couples to make intelligent choices about procreation and allow others to plan for their futures. Researchers have discovered, however, that testing presymptomatic individuals for HD is problematic on many fronts and fraught with issues that have wide-ranging consequences.
Although genetic testing of newborns for phenylketonuria and adults for the recessive sickle cell anemia gene has been in place for many years, past testing offers few insights applicable to the presymptomatic testing of individuals for the HD gene. Medical practitioners and patients themselves wonder if it makes sense to tell a person with no symptoms that he or she will surely get a disease for which there is not yet treatment or a cure.
At-risk Testing
Individuals who have one or more relatives with HD or a symptom-free relative who is a known carrier are said to be at-risk. According to the Huntington’s Disease Society of America, the prevalence of HD is estimated at 1/10, 000 individuals in the United States, with approximately 5 at-risk individuals for every currently affected person. These figures bring the total population to whom genetic testing might be applied to between 25,000-30,000 affected individuals and 125,000-150,000 at-risk individuals. After years of painstaking research, a genetic test called the direct gene test for HD is now available to those who are at-risk and want to know if they have the HD gene. If they do, they can expect to be stricken with HD in the future. If they have offspring, the gene might have been passed to them as well. If they do not yet have children, and they want them in the future, they can explore alternative reproductive strategies. The presence of the HD gene is referred to as a “positive” test result.
In the United States, only a small portion of people who are at-risk for HD request testing. One of the reasons is predictive testing offers no direct medical benefit at the present time; a positive result does not change the course of HD. In the future, if a method or medication to slow the progression of HD is discovered, then more at-risk individuals might request the predictive test. *****
The Decision to Know or Not to Know
The decision to be tested is a significant one. Life-altering choices have been made by individuals upon finding out they are positive for the HD gene. Broken engagements, divorces, and suicides have occurred. The reasons offered by those who want to undergo predictive testing usually relate to future planning—choices regarding marriage, reproduction, career, finances, or simply a need to relieve uncertainty. An individual considering testing should undergo non-directive counseling aimed at helping him/her to balance the potential psychological and social risks of testing against anticipated benefits. By protecting an individual’s right to autonomy, non-directive counseling affords patients an opportunity to make their own informed and voluntary decisions.
Components of HD Predictive Testing Process
1. Initial telephone contact by individual seeking the testing
2. A neurological evaluation
3. Genetic counseling
4. A signed informed consent to be tested document
5. A psychological assessment
6. A review with the client by a counselor of the potential impact of the test results
7. Disclosure of results to the client in person
8. A post-result follow-up
The Huntington’s Disease Society of America states: “The decision to take a predictive test for HD should always be an informed, carefully considered, and freely chosen personal decision. Individuals should not be coerced into testing by a spouse, another family member, a physician, an insurance company, or an employer.”
Moral and Ethical Issues
There are more questions than answers when it comes to the moral and ethical issues surrounding predictive testing for HD. Even the diagnosis of the illness itself presents antagonistic moral dilemmas.
For example, does a person who tests positive have an obligation to alert family members? What about the physician who delivers the information? Some say an individual who tests positive should tell his family so members can decide about taking the test themselves and make plans for the future. Others say not to alarm family members without the benefit of counseling for fear of an untoward reaction.
Along a similar vein, after diagnosing a patient with the illness, what moral/professional obligation does a physician have to inform his patient's family members that they are at risk? What professional attitude should a physician adopt when dealing with a positive-testing individual who wants information about reproductive decisions? Is a person’s right to privacy more important than the right of family members to know they are at-risk? Physicians have actually been sued for not warning family members of the possibility of the transmission of a genetically associated condition.
Other questions arise when the risk-benefit ratio to society is considered. Should society be expected to pay for the care and treatment of HD-affected offspring when the parents knew they were at risk, but refused to be tested before having children? Should laws be put into place to force at-risk individuals to be tested or to refrain from reproduction in the usual sense? Would this violate personal liberty and an individual’s right to privacy?
Ethicists, patients, physicians, at-risk individuals, researchers, nonprofit HD organizations, legislators, and public health officials are still wrestling with the ethics of predictive genetic testing, but at the present time, they are firmly upholding the right of an individual to privacy, confidentiality, informed consent, and voluntary predictive testing.
***** There is good news since the above article was written. In a May 2019 study published in the New England Journal of Medicine, researchers demonstrated for the first time that the drug, IONIS-HTTRX (now known as RO7234292) successfully lowered levels of the mutant huntingtin protein—the toxic protein that causes Huntingtons disease—in the central nervous system of patients.
Dr. Blair Leavitt, neurologist and director of research at the Centre for Huntington Disease, University of British Columbia, Canada, reports "this is a tremendously exciting and promising result for patients and families affected by this devastating genetic brain disorder." He goes on to say that not only are the toxic levels of the disease-causing protein lowered, but the drug is also safe and well-tolerated.
The results were from a trial involving 46 patients with early HD at centers in Canada, the United Kingdom, and Germany. Thirty-four of the test subjects received the drug and 12 received a placebo. The drug was administered monthly to patients via an injection directly into the cerebrospinal fluid.
Currently, the drug is being evaluated in a large clinical trial at the Centre for Huntington Disease at UBC and other HD centers around the world to determine whether the treatment slows or halts the progression of disease symptoms This is the first ray of hope for victims of Huntington's disease.
Articles on this site are written after careful research by the author of Twisting Legacy. Even so, the author is not an expert on any of the subjects. Please do your own research if you have questions about the authenticity of the information in the articles on this website.