Depression often occurs early in the course of the illness. Patients may be argumentative, impulsive, or erratic. Dementia develops as the disease progresses. Childhood cases tend to present with rigidity rather than with chorea. Younger patients may develop seizures.
Family history is of paramount importance in making the diagnosis.
If a patient with movement disorder or dementia is known to have a parent with HD, the diagnosis of HD is highly likely. The typical clinical picture of HD may appear in patients who have no family history of the disease. Whether the disease actually can arise de novo through new genetic mutations is unclear. Chorea is the most common movement disorder. In HD, chorea often appears as facial twitching or as twitching and writhing of the distal extremities.