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Living With Huntington Disease |
An at-risk person is someone who is living with the chance of developing Huntington disease -- whether a 50/50 chance or a greater than 50% chance (if determined through predictive testing.)
Some people at-risk live their lives with dread and gloom. Others try to ignore the possibility of developing HD. Many at risk people imagine that the period following diagnosis is a prolonged and unproductive wait on death row. They mistakenly perceive the end of their lives to be not at the moment of death, but at the moment when they are diagnosed as having symptoms of Huntington's. They ignore the years of productive and self-reliant living which are at their disposal even if they do have the disease.
The hereditary nature of HD, combined with the problem of adult onset and the fact that predictive testing is a very personal decision, make contemplation of marriage and the prospect of starting a family particularly difficult. Many at-risk individuals have already established families before they learn about HD or fully realize the hereditary nature of it.
HSC recommends that at-risk people know all the facts and alternatives before making decisions appropriate to their individual situation. Through genetic counselling, the full implications of the genetic characteristics of HD can be discussed and all the alternatives available (e.g. adoption, artificial insemination, predictive and prenatal testing, having a child without testing) can be considered.
Predictive testing for Huntington disease is a complicated process, both techncially and personally. It is only available to individuals 18 years of age or over. Detailed information is provided in an HSC booklet.
If possible, a blood sample from the at-risk individual and an affected family member are tested to determine whether or not the HD gene has been inherited. If blood from an affected family member is not available, it is possible to test only the at risk person. All predictive testing is based on recognizing patterns within genes.
Each cell of the human body contains 46 chromosomes, arranged in 23 pairs. In each pair, one chromosome comes from the mother and the other from the father. Chromosomes are made up of small units of genetic material called genes. The gene for HD is located on chromosome number 4.
Genes are made up of DNA (deoxyribonucleic acid.) DNA-molecules consist of chains of four small elements called bases. There are four bases: A (adenine), T (thymine), G (guanine) and C (cytosine.) Their order constitutes a code which determines the type of protein that the particular gene produces. Any change in the sequence of bases may cause a problem in the functioning of that protein.
Huntington disease is inherited in an autosomal dominant pattern. This means a man or woman with HD has a 50:50 chance to pass the genetic change or mutation that causes HD to each son or daughter. A person who has not inherited this genetic change will not develop HD and cannot pass HD on to a child.
In each cell of our body we have 46 chromosomes, which are arranged in 23 pairs. One chromosome from each pair is inherited from our mother, and the other from our father. Chromosomes are made up of small units of genetic material called genes. The gene for HD is located on chromosome 4.
Genes are made up of deoxyribonucleic acid, or DNA. DNA molecules consist of chains of four small elements called bases. There are four bases, known as A (adenine), T (thymine), G (guanine) and C (cytosine). Their order constitutes a code which determines the type of protein that a particular gene produces. Any change in the sequence of bases may cause a problem in the functioning of that protein.
The gene causing HD has been shown to have a region in which three of the bases (CAG) are repeated many times.
Recently published laboratory guidelines indicate that the normal gene contains 35 or fewer CAG repeats, while the disease-causing version has 36 or more repeats - inheriting one copy of the gene with this expansion is associated with the clinical presentation of Huntington disease.
A gene with 36-39 repeats falls into a "reduced penetrance" range, which may or may not be associated with the onset of HD symptoms. Individuals with 27-35 repeats on one of their two genes will not develop Huntington disease, but in rare instances can pass an expanded number (i.e., 36 or more) of CAG repeats to their offspring, who will then be at higher risk for HD.
Further advances in genetic studies of HD may provide additional or revised information in the future.
The decision about whether or not to take the predictive test is a deeply personal one. The at-risk person must balance the advantages and disadvantages of knowing whether s/he is likely to develop Huntington disease.
At the present time, there is neither a cure nor adequate treatment for HD. For that reason, the vast majority of at-risk people choose not to be tested. However, some individuals see testing as an opportunity, even though it is frightening.
Generally speaking, it would appear that the people who cope best are those who have known about HD from childhood and have discussed it freely and openly with relatives and close friends. They often have a remarkable appreciation for happiness and quality in life and a deep understanding of certain aspects of life which many others take for granted. Out of possible adversity comes an enriched perspective and a whole new range of more satisfying values and relationships.
Counselling is a vital part of predictive testing, both before and after the actual test. Before testing, a genetic counsellor helps the individual explore reasons for taking the test, and prepare for receiving results. After testing, counselling is geared to offering support and assistance in understanding the impact of the either negative or positive test results on the individual's life and that of the family. For more information about genetic counselling across Canada, contact the Society's national office or the Canadian College of Medical Geneticists.
List of Predictive Testing Clinics in Canada.
Testing of a pregnancy, known as prenatal ("before birth"), is technically similar to predictive testing. The HSC booklet on genetic testing also contains detailed information on prenatal testing. There are three different situations in which prenatal testing for HD may be done:
Ideally initial discussions about possible prenatal testing for HD should take place before pregnancy, for the future parents and the counsellors to have sufficient time to address all the important technical and emotional issues involved.
DNA banking allows storage of samples of DNA for future use. Storing DNA ensures that samples will be available should someone in a family wish to have predictive testing in the future. If DNA has not been banked and crucial family members have died, predictive testing may not be possible in some situations.
It is very important that DNA samples are stored from those individuals who have HD. It may also be important in some families to bank the unaffected husband or wife of the HD patient (i.e. the person whose children are at risk for HD). All information contained in the HD DNA Bank is confidential. Samples may be stored indefinitely and no results are disclosed to anyone unless specifically requested or authorized.
Hearing a diagnosis of Huntington disease is always hard. There are generally five steps we all go through when we are learning to cope with a difficult situation. People with HD and their family members go through the same steps.
The person who has just been diagnosed with HD should be encouraged to carry on normally, at work and at home, for as long as possible. It is often better to continue with lighter or easier jobs rather than retire from work or domestic duties altogether.
The quality of life of the person with HD and family is usually enhanced by therapeutic intervention: communication and swallowing therapy, physical therapy, occupational therapy, nutritional therapy, recreation (therapy) activities, music therapy, art therapy, pet therapy, relaxation therapy, and various discussion groups to reflect the interests of various individuals (music appreciation, Bible study, etc.) The Huntington Society of Canada has several helpful booklets, articles and videos on these subjects. In some communities there are day programs where people with HD get together to socialize, have fun and exercise. A sense of peace and acceptance often comes from being able to share with others who truly understand what one is going through.
It is also wise for the person with HD and his/her partner or caregiver to work out a cooperative method for dealing with safety and medical issues, such as driving, smoking and wearing a Medic-Alert bracelet.
A diagnosis of Huntington disease invariably deeply affects the person and every member of the family, as well as a wide circle of friends, work associates, neighbours, and others in the community. As with any serious diagnosis, the person with HD and the family can expect to experience a variety of emotions, some even frightening or contradictory. Disbelief or denial, rage, despair, guilt, shame, sadness, loneliness, self-pity, envy of others' good health, relief that a diagnosis has finally been made, thoughts of "why me?" -- all of these feelings and many others are common and normal reactions.
Families should keep in mind that their physical and emotional needs are important and should be met. They should not be afraid to ask questions and should make sure they understand the answers. Families must also remember that needs vary over time and a solution for one stage of life may have to be re-examined at another. Counselling can go a long way toward helping persons with HD and their families retain maximum productivity and acceptance while coping with a difficult and challenging situation.
The whole family must understand what is happening. It is important to accept the truth -- that a family member has HD -- and speak openly about the situation. It may be very helpful for children to realize that it is the illness, and not them, causing a parent's outbursts. There are helpful articles available on the needs and reactions of children.
Chronic illness like HD tends to isolate family members from people just when they need them most. Truth and honesty within the family helps friends and relatives feel more comfortable in their relationships with the person with HD and makes it easier to lend much needed help and support.
Persons with HD and their partners sometimes experience role changes. Over time, the relationship will become drastically altered, and the person with HD will be less of a friend, companion and lover. Common sexual problems are loss of desire, inability to have sex, and conflicting desires and needs. A general loss of desire may be due to depression, medication or emotional problems. This change in the relationship adds personal grief to a complex situation, and both the partner and the individual with HD may need professional support to deal with these changes.
Thoughts of suicide happen with persons who have Huntington disease, but talking about suicide does not make it happen. In fact, talking about it can often uncover alternative solutions to what seems to be an intolerable situation.
Family members experiencing changes in the behaviour of the person with HD may not realize that this does occur in HD. Feeling that it is unique to their family, they may not wish to share it, or try to handle it on their own, and further isolate themselves.
Because of the efforts of the Huntington Society of Canada, there are many resources available to HD families. A wide range of informative publications and videos can be purchased or borrowed, (recommended reading: Understanding Huntington Disease: A Resource for Families.) Chapters and area representatives in each province can put the family in touch with a large network of support, both lay and professional, to help the family cope.
Long-range financial and legal planning is important to consider -- for someone who has just been diagnosed or for someone at risk. Topics to discuss with a lawyer may include giving a power of attorney, perhaps changing one or both wills depending on their provisions, changing ownership of property such as the house and cottage, making bank accounts and safety deposit boxes available to the other partner and so on.
Obtaining insurance coverage for persons at risk has become a very serious problem. The Huntington Society of Canada is monitoring the situation in Canada and globally through the International Huntington Association.
It is critical that the primary caregiver, whether it be the partner or someone else, take good care of him/herself. This is not being selfish -- it is essential for one's own sake and that of the person with HD. It is important to arrange times for recreation and socialization and talks with friends and relatives, and to set realistic goals -- to undertake only as much as can be reasonably accomplished and give precedence to things that are really important. (Suggestions and tips for the caregiver can be found in the publication, Understanding Huntington Disease: A Resource for Families.)
Action Plan for Caregivers (Horizon Fall 1995)