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Testing for Huntington’s Disease
In 1993, a groundbreaking advancement in genetic testing transformed the way individuals at-risk of Huntington’s disease could determine their likelihood of developing symptoms. This biochemical testing method enables those with a family history of Huntington’s to discover whether they carry the mutated gene and may eventually develop symptoms. The process involves extracting DNA from a blood sample and quantifying the amount of mutated protein in the Huntingtin gene.
It is crucial to note that while a positive genetic test confirms the presence of the mutated gene, it does not predict the onset or severity of symptoms due to the complex nature of Huntington’s disease. Below you will find information on the different types of testing processes available:
Clinical Use of Testing
For any hereditary condition, the requirement for testing varies depending on the individual being tested, their family history-based risk prediction and various psychosocial aspects involved in undergoing a genetic testing irrespective of the result. There are specific set of requirements for individuals falling under each of the above-mentioned categories. Below is the summary of what you need to remember prior to thinking about genetic testing, please click on the below links to know more based on your current requirements.
Genetic Testing
Genetic Testing is recommended for individuals who have undergone neurological analysis and are exhibiting symptoms typical of Huntington’s disease. This testing is crucial to establish a definitive diagnosis, allowing for appropriate modification of management if necessary.
While the process may seem straightforward, it’s essential to note that several adult-onset neurological conditions share symptoms with Huntington’s disease. Therefore, it is prudent to be prepared for a 50-50 chance of receiving either a positive or a negative report.
A positive genetic testing result not only helps alleviate the uncertainty surrounding symptoms but also carries implications beyond the individual. It is advised to consider psychological therapy for the family, both in preparation for and after receiving a definitive diagnosis. Some individuals may receive results suggestive of an “intermediate allele” count, which has different implications compared to a “pathogenic allele” result.
On the other hand, a negative report might bring relief, but it underscores the importance of returning to your neurologist for a more in-depth analysis of your symptoms. This step is crucial to finding ways to manage or treat the symptoms an individual is experiencing. The diagnostic testing process is a vital step in navigating the complexities of Huntington’s disease and ensuring appropriate care and support.
Predictive or Pre-symptomatic Testing
Predictive testing is typically offered to individuals without apparent symptoms and have a family history of Huntington’s disease.
Due to the complexity of environmental and genetic factors influencing disease progression, the gene-symptom correlation varies between individuals. Even with a repeat number similar to their parent’s, some individuals may never develop symptoms or experience onset later in life, unrelated to their parent’s timeline.
In addition to the mentioned conditions, extra caution is exercised for predictive testing in adult-onset Huntington’s disease, available only to individuals over 18. Due to the profound repercussions of these results, careful measures are taken, including referral to psychological counselling. The mental health status of the person receiving the news is assessed, and test results are kept confidential unless the individual provides consent to share with family.
Choosing predictive testing is a deeply personal decision, one that should be made after a thorough understanding of the complexities associated with testing for a progressive adult-onset neurological condition.
Prenatal Screening
Prenatal Diagnosis for Huntington’s disease is a pivotal process offering expectant parents the opportunity to ascertain if their unborn child has inherited the condition, involving consultations with genetic counsellors and the option of undergoing either Chorionic Villus Sampling (CVS) or Amniocentesis procedures to obtain fetal genetic material for testing.
Preimplantation Screening
Preimplantation Genetic Testing, integrated into the IVF cycle, allows for the selection of embryos without genetic mutations, providing individuals control over their reproductive choices based on genetic testing results.
Where to start?
If you are considering predictive or genetic testing for Huntington’s disease, here are the steps involved. If you have any questions, please contact us directly.
Visit Your GP
Obtain a referral from your general practitioner to one of the genetic testing clinics.
Genetic Counselling
We recommend visiting a genetic counsellor where you may discuss the family history, the genetics, the reason that you are seeking testing, and potential impacts of any test result.
Visit the Clinic
After your initial genetic counselling session, if you choose to progress, you will undergo a blood test. The test involves extracting DNA from a blood sample. Results typically take between 8 to 12 weeks to be received.
It is a personal choice
There is no right or wrong decision whether to undergo predictive testing for Huntington’s disease, it is a personal choice and should be carefully considered.
Genetic counselling is a supportive discussion-based process to help you consider all relevant factors before making an informed decision. If you are wanting to explore IVF/PGD family planning options, you can also raise this with the genetic counsellor in your first appointment.
Other counselling support may be helpful to explore the outcomes and make sure you’re emotionally ready to make the decision.