What Are Some Of The Means For Huntington’s Disease Diagnosis?

Huntington's disease, or HD, is a disorder that can cause your nerve cells to break down over time. This often leads to a loss of movement and cognition. The diagnostic process for HD can involve many components, such as your family history, symptomatic or pre-symptomatic testing, lab testing, genetic testing, and brain imaging. Counseling is often provided alongside the diagnostic process, but for additional support, you might consider online therapy as a convenient method of mental health care.

The HTT gene

Huntington's disease can be defined as an inherited disorder involving an HTT gene mutation. The HTT gene generally creates huntingtin, a protein. It's believed that huntingtin may play a vital role in the health of nerve cells, and if the HTT gene is mutated, it could eventually lead to nerve cell death.

The history of Huntington's disease diagnoses

Huntington's disease has likely been around for a long time, but in 1872, George Huntington is generally believed to have been the first to describe it entirely and observe how it affected families genetically. Despite his work, HD patients were often misdiagnosed in the past.

The most famous example may be Woody Guthrie, a famous singer from the 1930s to the 1950s. His mother had Huntington’s Disease, but Guthrie was misdiagnosed with alcohol use disorder as his health deteriorated. Guthrie’s decline caused him to be institutionalized several times. Eventually, he received the correct diagnosis, but by then, it was too late for him to be treated for his symptoms.

Nowadays, it is typically much easier to diagnose HD. Below, you can read about how neurologists usually navigate the diagnostic process.

Common ways of diagnosing Huntington's disease

Family history 

One of the most apparent indicators of HD can be family history. If you have a family history of HD, your chances of developing the disease tend to increase. However, not everyone with a family history of HD will develop the disorder.

Symptomatic testing

Next, the doctor may then test the patient's mental and physical symptoms. First, they may ask if the patient has been experiencing any cognition or emotional troubles and then test their hearing, strength, eye movements, and reflexes, as well as their sensitivity, balance, and movement.

Lab testing

Lab tests are often done as well. These tests can help the doctor either rule out HD or build a case for an HD diagnosis.

Pre-symptomatic testing

Pre-symptomatic testing can be another way of testing for HD. It is typically done when a person has no symptoms of HD, but does have a family history of the disease. This type of genetic testing usually involves markers, or inherited DNA pieces that can be close to a gene. This test normally also requires DNA from the family, so if you were adopted or have few remaining family members, you may not be able to take the test. 

Genetic testing and Huntington's disease

When performing this testing, they can look at the repeats in your DNA known as the CAG repeats. The number of repeats can determine whether you may develop HD or if you're at risk. If there are fewer than 28 repeats, this is usually considered normal. You and your children likely won’t develop HD.

If the test shows 29 to 34 repeats, you may not develop HD, but your children may be at risk for HD.

At 35 to 39 repeats, both you and your children may or may not develop the disease. Those in this range should generally check regularly to be sure they haven't developed it.

At over 40 repeats, you will almost certainly develop HD, and your children will usually have a 50% chance of developing it as well.

Brain imaging

During the diagnosis process, you may be asked to undergo a brain imaging test, which can create a picture of your brain without causing discomfort. Due to the breakdown of nerve cells, HD can cause the brain to shrink. You may lose 30% of your original brain weight at later stages of the disease. Brain imaging can determine the possible prognosis of the disease if you have it.

However, shrinkage of the brain does not necessarily mean you have HD, as other disorders can cause this, too. In addition, your brain may appear normal during the early stages of HD.

Where can I get tested?

The best way to test for HD is typically through genetic testing, which can be an inexpensive and accurate way to test those at risk of HD. To find testing centers near you, you can go to the Huntington Disease Society of America's website or call them at 1-800-345-HDSA.

What can you expect at one of these tests? You may begin by having an examination of your neurological abilities. This can help the doctor determine whether you are experiencing any symptoms of HD, which can aid them in diagnosing you.

Then, there is usually pre-test counseling, during which you can learn all about HD. Doctors can further explain the test and talk about the outcomes you may experience. They may then give you a choice to be tested or not. The doctor won't usually pressure you into getting tested if you don't want to.

Once you undergo a test, which involves a small blood sample, professionals can help you prepare for the results. There’s often a lot of counseling involved with this test due to the potential impact of the disease.

After the test

The results will normally be handed to the individual. A follow-up appointment may happen regardless of whether the results are positive or negative.

Typically, the person tested for HD is over 18 unless a minor has symptoms. Juvenile Huntington's disease tends to be rare but can occur, and testing may be done if a child has symptoms.

There usually won't be testing done on a fetus of expectant parents. It is frequently recommended that parents who don't want to pass HD to their children seek genetic counseling to have the best options possible. Parents may wish to consider preimplantation screening as well. This normally involves creating multiple embryos in a lab using the parents' DNA and screening them for any signs of HD. If an embryo does not have the HD gene, it can be implanted inside the mother.

Support through online therapy

People going through the HD diagnostic process, as well as those living with Huntington’s Disease and their caregivers, can often benefit from mental health care. Online therapy can be a convenient option for this type of professional support, as you can attend sessions from the comfort of your home or anywhere with an internet connection, at a time that fits into your existing schedule.

A 2023 study investigated the efficacy of online therapy for treating depression in people living with chronic diseases. It found that internet-based cognitive behavioral therapy “effectively reduces depressive symptoms in patients with comorbid depression and chronic diseases,” suggesting that online therapy could be helpful for people living with HD who are also experiencing depression symptoms.