The extent of the hyperkinesia exhibited in the disease can vary from solely the little finger to the entire body, resembling purposeful movements but occurring involuntarily. In children, rigidity and seizures are also symptoms. Other hyperkinetic symptoms include:

Head turning to shift eye position
Facial movements, including grimaces
Slow, uncontrolled movements
Quick, sudden, sometimes wild jerking movements of the arms, legs, face, and other body parts
Unsteady gait
Abnormal reflexes
"prancing," or a wide walkThe disease is characterized further by the gradual onset of defects in behavior and cognition, including dementia and speech impediments, beginning in the fourth or fifth decades of life. Death usually occurs within 10–20 years after a progressive worsening of symptoms. Caused by the Huntington gene, the disease eventually contributes to selective atrophy of the Caudate nucleus and Putamen, especially of GABAergic and acetylcholinergic neurons, with some additional degeneration of the frontal and temporal cortices of the brain. The disrupted signaling in the basal ganglia network is thought to cause the hyperkinesia. There is no known cure for Huntingtons disease, yet there is treatment available to minimize the hyperkinetic movements. Dopamine blockers, such as haloperidol, tetrabenazine, and amantadine, are often effective in this regard. Wilsons disease
Wilsons disease (WD) is a rare inherited disorder in which patients have a problem metabolizing copper. In patients with WD, copper accumulates in the liver and other parts of the body, particularly the brain, eyes and kidneys. Upon accumulation in the brain, patients may experience speech problems, incoordination, swallowing problems, and prominent hyperkinetic symptoms including tremor, dystonia, and gait difficulties.
Some infants are born with an opening in the roof of the mouth, which is called a cleft palate. Severe nearsightedness (high myopia) is sometimes present, as are other eye problems that can affect vision such as detached retinas. About one-quarter of people with this condition have mild to moderate hearing loss. Causes
Spondyloepiphyseal dysplasia congenita is one of a spectrum of skeletal disorders caused by mutations in the COL2A1 gene. The protein made by this gene forms type II collagen, a molecule found mostly in cartilage and in the clear gel that fills the eyeball (the vitreous). Type II collagen is essential for the normal development of bones and other connective tissues. Mutations in the COL2A1 gene interfere with the assembly of type II collagen molecules, which prevents bones from developing properly and causes the signs and symptoms of this condition.Spondyloepiphyseal dysplasia congenita is inherited in an autosomal dominant pattern, which means one copy of the altered gene is sufficient to cause the disorder. Management
There is no treatment for the underlying condition. Supportive/symptomatic treatment is based on the traits present in each person with the condition. Notable people
Michael Dunn, American actor, Tony winner, Wild Wild West, Star Trek
Warwick Davis, English actor and TV presenter

References
Spranger: Bone Dysplasias, Urban & Fischer 2002, ISBN 3-437-21430-6

Further reading
GeneReviews/NIH/NCBI/UW entry on X-Linked Spondyloepiphyseal Dysplasia Tarda
OMIM entries on X-Linked Spondyloepiphyseal Dysplasia Tarda


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