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Patients With Extreme Early Onset Juvenile Huntington Disease Can Have Delays in Diagnosis: A Case Report and

Ashley A Moeller1, Marcia V Felker1, Jennifer A Brault2

  • 1Indiana University School of Medicine, Indianapolis, IN, USA.

Child Neurology Open
|August 23, 2021
PubMed

Insights

Huntington disease (HD) is a genetic disorder caused by CAG repeat expansion. This case details extreme early-onset juvenile HD in a boy with over 250 repeats, presenting severe symptoms by age two.

Area of Science:

  • Genetics
  • Neurology
  • Pediatrics

Background:

  • Huntington disease (HD) is a neurodegenerative disorder caused by CAG trinucleotide repeat expansion in the HTT gene.
  • Juvenile-onset HD (jHD) typically presents with over 60 CAG repeats and symptom onset before age 20.

Observation:

  • A case of a young boy with paternally inherited jHD presenting with extreme early onset between 18-24 months.
  • The patient exhibited an ataxic gait, truncal titubation, and speech delay, with MRI revealing cerebellar atrophy.

Findings:

  • Genetic analysis revealed 250 to 350 CAG repeats, one of the largest expansions reported.
  • The patient experienced rapid neurological regression, becoming nonverbal, wheelchair-bound, and requiring a feeding tube.

Implications:

  • This case highlights the extreme end of the CAG repeat expansion spectrum in jHD.
  • Diagnostic delays due to patient age and ethical considerations in pediatric genetic testing are significant.
  • Understanding extreme repeat expansions is crucial for predicting disease severity and progression in juvenile Huntington disease.

Keywords:
MRIcerebellumdevelopmental delayethicsgeneticshuntington disease

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