The HD gene is present from birth, but the age of onset is usually in the third or fourth decade of life. While this is the most common time for symptoms to appear, there have been reports of onset as young as 2 and as old as 80. Symptoms begin gradually and progress over time. Because of this, quality care and attention to changes in the affected individual's condition can often prevent or minimize complications and increase quality of life. It is commonly seen as restless, wriggling movements of the fingers or toes in the early stages of the disease.
Movements tend to become larger over time and can involve the face, arms, trunk and legs.
Chorea may appear more pronounced when an individual is under stress or experiencing an extreme of emotion. Rigidity or muscle stiffness and slowness may also be present. This is more common when onset occurs in childhood or adolescence and also in more advanced disease. Both chorea and rigidity can interfere with mobility and coordination. Changes in mood are often first noticed by family members.