Juvenile Huntington disease (JHD) is a devastating neurodegenerative disease that is characterized by behavioral, cognitive, and motor decline. While most clinicians learn about Huntington disease during professional training, many may not be aware of its onset during childhood and adolescence. JHD accounts for 5% to 10% of Huntington disease cases. Manifestation of the disease before age 21 is considered juvenile onset; childhood onset occurs before age 11.