How is Huntingtons Disease diagnosed?

Huntington's disease is diagnosed primarily through a combination of clinical neurological examination and definitive genetic testing that identifies an expansion of the CAG trinucleotide repeat in the HTT gene. While symptoms often lead patients to seek medical help, a confirmed diagnosis relies on the presence of these genetic markers to confirm the underlying cause of motor, cognitive, and psychiatric symptoms.

How is Huntington's disease diagnosed?

The diagnostic process for Huntington's disease is a multi-step journey. Typically, a neurologist or movement disorder specialist will begin by conducting a comprehensive physical and neurological exam to assess motor function, reflexes, and coordination. Because Huntington's disease can present with subtle symptoms like mood swings or slight balance issues, physicians look for the characteristic triad of motor, cognitive, and psychiatric impairments. The definitive confirmation is a blood-based genetic test that measures the number of CAG repeats in the HTT gene; having 40 or more repeats is considered fully penetrant, confirming a diagnosis of Huntington's disease.

What is the typical diagnostic odyssey for patients?

Many individuals experience a frustrating "diagnostic odyssey" because the early symptoms of Huntington's disease—such as irritability, depression, or minor involuntary movements—are often misattributed to other mental health or neurological conditions. It is common for patients to see several general practitioners or psychiatrists before a neurologist recognizes the pattern and orders the specific genetic test. This delay is emotionally taxing, and it is important to validate that your search for answers is a difficult but necessary process. Currently, 39 people with Huntington's disease have joined the DiseaseMaps community to share their experiences, highlighting the value of connecting with others who have navigated this path.

What conditions are commonly confused with Huntington's disease?

Because Huntington's disease affects the brain's basal ganglia, it can be clinically confused with several other movement and neurodegenerative disorders. A specialist must perform a differential diagnosis to rule out conditions that share similar features, including:

• Sydenham’s chorea: A post-streptococcal movement disorder.


• Neuroacanthocytosis: A group of rare genetic disorders involving movement and red blood cell abnormalities.


• Wilson’s disease: A disorder of copper metabolism that can cause movement issues and psychiatric symptoms.


• Spinocerebellar ataxias: Genetic disorders that primarily affect balance and coordination.


• Drug-induced dyskinesia: Involuntary movements caused by long-term use of certain medications.

Why is seeing a specialist essential?

Seeking care from a neurologist or a movement disorder specialist is critical because Huntington's disease is complex and requires nuanced management. General practitioners may not see this condition often, which can lead to delayed or missed diagnoses. A specialist will not only provide an accurate diagnostic assessment but will also offer access to genetic counseling, which is vital for understanding the 50% inheritance risk for offspring and the implications of the genetic results for family members. If you suspect you or a loved one may have Huntington's disease, requesting a referral to a center of excellence or a movement disorder clinic is the most effective next step.

Next steps

• Consult a neurologist or a movement disorder specialist to discuss your specific symptoms.


• Ask for a referral to a certified genetic counselor to discuss the implications of HTT gene testing.


• Connect with the 39 community members on DiseaseMaps.org who have lived experience with this condition.


• Reach out to the Huntington’s Disease Society of America (HDSA) or similar national organizations for regional clinical resources.

Medical disclaimer: This content is for educational purposes only and does not constitute professional medical advice, diagnosis, or treatment; always seek the advice of your physician or other qualified health provider with any questions regarding a medical condition.

References

• NIH Genetic and Rare Diseases Information Center (GARD): Huntington's Disease Overview.


• Orphanet: Rare Disease Database (ORPHA: 399).


• OMIM (Online Mendelian Inheritance in Man): Huntington Disease; HD (Entry #143100).


• Huntington’s Disease Society of America (HDSA): Clinical Guidelines and Resources.