Familial paroxysmal kinesigenic dyskinesia

Description

Familial paroxysmal kinesigenic dyskinesia is a disorder characterized by episodes of abnormal movement that range from mild to severe. In the condition name, the word paroxysmal indicates that the abnormal movements come and go over time, kinesigenic means that episodes are triggered by movement, and dyskinesia refers to involuntary movement of the body.

People with familial paroxysmal kinesigenic dyskinesia experience episodes of irregular jerking or shaking movements that are brought on by sudden motion, such as standing up quickly or being startled. An episode may involve slow, prolonged muscle contractions (dystonia); small, fast, "dance-like" motions (chorea); writhing movements of the limbs (athetosis); or, rarely, flailing movements of the limbs (ballismus).

Familial paroxysmal kinesigenic dyskinesia may affect one or both sides of the body. The type of abnormal movement varies among affected individuals, even among members of the same family. In many people with familial paroxysmal kinesigenic dyskinesia, a pattern of symptoms called an aura immediately precedes the episode. The aura is often described as a crawling or tingling sensation in the affected body part. Individuals with this condition do not lose consciousness during an episode and do not experience any symptoms between episodes.

Individuals with familial paroxysmal kinesigenic dyskinesia usually first experience episodes during childhood or adolescence.  Episodes typically last less than five minutes, and the frequency of episodes ranges from one per month to 100 per day. In most affected individuals, episodes occur less often with age.

In some people with familial paroxysmal kinesigenic dyskinesia the disorder begins in infancy with recurring seizures characteristic of those in a condition called benign familial infantile seizures. These seizures usually develop in the first year of life and stop by age 3. When benign familial infantile seizures are associated with familial paroxysmal kinesigenic dyskinesia, the condition is known as infantile convulsions and choreoathetosis (ICCA). In families with ICCA, some individuals develop only benign familial infantile seizures, some have only familial paroxysmal kinesigenic dyskinesia, and others have ICCA, which has features of both conditions.

Frequency

Familial paroxysmal kinesigenic dyskinesia is estimated to occur in 1 in 150,000 individuals. For unknown reasons, this condition affects more males than females.

Causes

Familial paroxysmal kinesigenic dyskinesia can be caused by variants (also known as mutations) in the PRRT2 gene. The protein produced from this gene helps control signaling between nerve cells (neurons) in the brain. PRRT2 gene variants, which reduce the amount of PRRT2 protein, lead to abnormal neuronal signaling. This altered activity in the brain is thought to underlie the movement problems associated with familial paroxysmal kinesigenic dyskinesia.

Not everyone with this condition has a variant in the PRRT2 gene. Variants in other genes involved in signaling in the brain are rare causes of familial paroxysmal kinesigenic dyskinesia. The genetic cause is unknown in other affected families. Noninherited (somatic) variants in the same and other genes can cause paroxysmal kinesigenic dyskinesia in people with no family history of the disorder. The nonfamilial form is referred to as sporadic paroxysmal kinesigenic dyskinesia.

Inheritance

This condition is inherited in an autosomal dominant pattern. Autosomal dominant inheritance means that one copy of an altered gene in each cell is sufficient to cause the disorder. In most cases, an affected person has one parent with the condition.

Autosomal dominant inheritance. Credit: U.S. National Library of Medicine.

Other Names for This Condition

• Dystonia 10
• Episodic kinesigenic dyskinesia
• Familial paroxysmal dystonia
• Paroxysmal kinesigenic choreoathetosis
• Paroxysmal kinesigenic dyskinesia

Where this page came from

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