Understanding Huntington’s Disease: Causes and Symptoms

Imagine knowing you carry a gene that could cause your body and mind to deteriorate over time—yet there's nothing you can do to stop it. This is the difficult reality for individuals living with Huntington’s disease (HD). A rare, inherited neurodegenerative disorder, Huntington’s disease affects the brain, leading to progressive loss of movement, cognition, and emotional stability.

In this blog, we break down what science has uncovered about what causes Huntington’s disease and how its symptoms appear and progress.

What is Huntington’s Disease?

Huntington’s disease is a genetic disorder that causes the progressive breakdown of nerve cells in the brain. It is autosomal dominant, meaning only one copy of the defective gene—passed down from either parent—is sufficient to cause the disorder.

According to the National Institute of Neurological Disorders and Stroke (NINDS), symptoms typically appear between the ages of 30 and 50 but can emerge earlier or later (NINDS, 2020).

Source:

National Institute of Neurological Disorders and Stroke. (2020). Huntington’s disease information page. https://www.ninds.nih.gov/health-information/disorders/huntingtons-disease

What Causes Huntington’s Disease?

Huntington’s disease is caused by a mutation in the HTT gene, which encodes the huntingtin protein. This mutation results in an expanded CAG trinucleotide repeat—a specific DNA sequence that repeats more than normal. A person with more than 40 repeats will eventually develop the disease (Walker, 2021).

The mutant protein gradually damages neurons in the brain, particularly in the basal ganglia, an area critical for movement and coordination.

Source:

Walker, F. O. (2021). Huntington's disease. The Lancet, 396(10261), 2190–2202. https://doi.org/10.1016/S0140-6736(20)32377-3

Key Symptoms of Huntington’s Disease

The symptoms of HD typically fall into three categories—motor, cognitive, and psychiatric:

1. Motor Symptoms:

Involuntary jerking or writhing (chorea)

Muscle rigidity or contracture (dystonia)

Slow or abnormal eye movements

Impaired gait, posture, and balance

Difficulty with speech or swallowing

2. Cognitive Symptoms:

Trouble organizing or focusing on tasks

Impaired judgment

Difficulty learning new information

Memory loss

Difficulty in multitasking

3. Psychiatric Symptoms:

Depression

Irritability or apathy

Anxiety

Obsessive-compulsive behaviors

Social withdrawal

These symptoms gradually worsen over time. In the later stages, individuals often lose the ability to speak, walk, or care for themselves.

Source:

Ross, C. A., et al. (2019). Huntington disease: natural history, biomarkers, and prospects for therapeutics. Nature Reviews Neurology, 15(4), 231–246. https://doi.org/10.1038/s41582-019-0145-6

Juvenile Huntington’s Disease

A rare form of HD, called Juvenile Huntington’s disease, occurs in people under age 20. It tends to progress more rapidly and presents with slightly different symptoms, including:

Decline in school performance

Seizures

Rigidity rather than chorea

Source:

Moser, D. J., et al. (2019). Juvenile-onset Huntington disease: A review of clinical and genetic characteristics. Pediatric Neurology, 98, 21–25. https://doi.org/10.1016/j.pediatrneurol.2019.03.011

Is There a Cure?

Currently, there is no cure for Huntington’s disease, but treatments are available to manage symptoms. Medications like tetrabenazine help control chorea, and antidepressants or mood stabilizers are often prescribed for psychiatric symptoms (Frank, 2019).

Gene therapy and RNA interference techniques are being actively explored in clinical trials to slow or halt disease progression (Tabrizi et al., 2022).

Source:

Tabrizi, S. J., et al. (2022). Targeting huntingtin expression in patients with Huntington’s disease. The New England Journal of Medicine, 386(24), 2286–2295. https://doi.org/10.1056/NEJMoa2202852

Final Thoughts

While a diagnosis of Huntington’s disease can be devastating, advances in genetic testing, clinical trials, and supportive care offer hope for patients and families. Early recognition of symptoms and access to a multidisciplinary care team can significantly improve quality of life.

To learn more about how technology is advancing rare disease diagnosis, visit our blog: The Role of Technology in Rare Disease

References:

Frank, S. (2019). Treatment of Huntington’s disease. Neurotherapeutics, 17(1), 154–160. https://doi.org/10.1007/s13311-019-00770-x

Moser, D. J., et al. (2019). Juvenile-onset Huntington disease: A review of clinical and genetic characteristics. Pediatric Neurology, 98, 21–25. https://doi.org/10.1016/j.pediatrneurol.2019.03.011

National Institute of Neurological Disorders and Stroke. (2020). Huntington’s disease information page. https://www.ninds.nih.gov/health-information/disorders/huntingtons-disease

Ross, C. A., et al. (2019). Huntington disease: natural history, biomarkers, and prospects for therapeutics. Nature Reviews Neurology, 15(4), 231–246. https://doi.org/10.1038/s41582-019-0145-6

Tabrizi, S. J., et al. (2022). Targeting huntingtin expression in patients with Huntington’s disease. The New England Journal of Medicine, 386(24), 2286–2295. https://doi.org/10.1056/NEJMoa2202852

Walker, F. O. (2021). Huntington's disease. The Lancet, 396(10261), 2190–2202. https://doi.org/10.1016/S0140-6736(20)32377-3