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Juvenile Huntington’s Disease: A Guide for Patients and Families – What Recent Research Tells Us

What You’ll Learn

This article summarizes a comprehensive clinical review of juvenile Huntington’s disease (JHD), a rare form of Huntington’s disease (HD) that affects children and teens. We’ll break down what JHD is, its symptoms, how it’s diagnosed, treatment options, and what families need to know to navigate care. The review, published in the Journal of Huntington’s Disease, draws on expertise from the European Huntington Disease Network to bring clarity to this complex condition.

A Quick Look at Juvenile Huntington’s Disease

Huntington’s disease (HD) is an inherited brain disorder caused by a faulty gene (called HTT) with too many repeats of a DNA segment known as “CAG.” Most people with HD develop symptoms in adulthood (adult-onset HD, or AOHD). Juvenile HD (JHD) is rare and affects fewer than 10% of all HD patients, with symptoms starting before age 20. Some experts now use “pediatric HD (PHD)” for children under 18 and “juvenile onset HD (JOHD)” for anyone with onset ≤20, regardless of current age, to avoid confusion.

Why This Research Matters

JHD is often misdiagnosed because its symptoms can look like more common childhood conditions (e.g., autism, ADHD). This review brings together decades of research to help families and doctors recognize JHD earlier, understand its progression, and access better care. For rare diseases like JHD, summaries like this are critical to ensuring patients don’t fall through the cracks.

Key Findings from the Clinical Review

1. Symptoms: How JHD Differs by Age

JHD symptoms vary depending on when they start (before age 10 vs. 11–20 years):

  • Children under 10:

    • Motor symptoms: Speech problems (e.g., slurred speech), stiffness (rigidity), involuntary muscle contractions (dystonia), and trouble walking (ataxia) are most common. Chorea (jerky, uncontrolled movements) – a hallmark of adult HD – is rare here.
    • Cognitive symptoms: Declining school performance (e.g., trouble reading, regression in skills) is often the first sign.
    • Unique features: Seizures (affecting ~50% of kids), spasticity (stiff muscles), pain (often in the legs), itching (without a skin cause), and possibly liver steatosis (fatty liver).
  • Teens (11–20 years):

    • Symptoms may look more like adult HD, with chorea, mood swings, and depression.
    • Behavioral issues (irritability, aggression, suicidal thoughts) are more common than in younger kids.

2. Disease Progression: Faster Than Adult HD

JHD progresses more quickly than adult HD, and life expectancy is shorter. On average, adults with HD live 15–20 years after symptoms start; for JHD, this is often shorter, especially if the CAG repeat length is very long (>73 repeats). By the end stage, most JHD patients need full-time care, including help with eating (tube feeding) and movement.

3. Diagnosis: Challenges and Steps

Diagnosing JHD can be tricky due to its rarity and overlapping symptoms with other conditions. Here’s how doctors approach it:

  • Clinical clues: A family history of HD, plus symptoms like declining school performance, seizures, or rigidity.
  • Genetic testing: A DNA test confirms the diagnosis by checking for CAG repeats in the HTT gene. Most JHD patients have >55 CAG repeats. However, genetic testing in children is controversial (many countries discourage it unless symptoms are clear) because it can’t be “undone” and may cause emotional distress.
  • Other tests: Brain MRI may show shrinkage in the striatum (a brain region affected by HD), and neuropsychological tests can track cognitive decline over time.

4. Genetics: Why JHD Runs in Families

JHD is inherited in an autosomal dominant pattern: if one parent has the faulty HTT gene, each child has a 50% chance of inheriting it. JHD often comes from paternal transmission (from father to child) due to a genetic phenomenon called “anticipation,” where CAG repeats expand as the gene is passed down, leading to earlier onset in children than in the parent.

5. Treatment: Managing Symptoms (No Cure Yet)

There are no FDA-approved treatments specifically for JHD, but doctors focus on relieving symptoms:

  • Motor symptoms: Muscle relaxants (e.g., baclofen) for spasticity; levodopa for rigidity; botulinum toxin injections for focal dystonia.
  • Seizures: Valproic acid is the most commonly used anticonvulsant.
  • Behavioral/cognitive symptoms: Antidepressants (SSRIs) for mood issues; antipsychotics (e.g., quetiapine) for aggression or psychosis.
  • Pain/itching: Acetaminophen or NSAIDs for pain; gabapentin may help with itching.

Multidisciplinary care is key: teams often include neurologists, physical therapists, speech therapists, dietitians, and mental health providers.

What This Means for Patients and Families

  • Early recognition is critical: If your child has unexplained declines in school, seizures, or unusual movements – especially with a family history of HD – ask your doctor about JHD.
  • Diagnostic delays are common: Symptoms like behavioral issues may be misdiagnosed as ADHD or autism. Trust your instincts and advocate for further testing if concerns persist.
  • Family support matters: Caring for a child with JHD is emotionally and physically challenging. Connect with organizations like the Huntington’s Disease Youth Organization (HDYO) for resources and peer support.

Gaps in Knowledge & Future Hopes

Researchers are working to improve JHD care:

  • Better diagnostics: Blood tests (e.g., neurofilament light, a protein released when neurons die) and advanced MRI scans may help diagnose JHD earlier.
  • New treatments: Trials are exploring therapies to slow disease progression, including gene silencing and mitochondrial support (e.g., ketogenic diet).
  • Clearer guidelines: There’s an urgent need for standardized treatment protocols for JHD, as current care relies on expert opinion.

Key Points to Remember

  • JHD is a rare, inherited form of HD with onset before age 20.
  • Symptoms vary by age: young children often have rigidity and seizures; teens may have chorea and mood issues.
  • Diagnosis requires clinical judgment, family history, and genetic testing (when appropriate).
  • Treatment focuses on managing symptoms; multidisciplinary care is essential.
  • Research is advancing, with new tools to diagnose and treat JHD on the horizon.

Talk to Your Doctor

If you suspect JHD in your child, ask:

  • What tests can help confirm or rule out JHD?
  • How can we manage specific symptoms (e.g., seizures, pain)?
  • Are there clinical trials or specialized HD centers we should consider?

You know your child best. Working closely with a team experienced in HD can make a big difference in their care.

This article is based on “Clinical Review of Juvenile Huntington’s Disease” (Oosterloo et al., 2024, PMCID: PMC11307030).