Paroxysmal dyskinesia quinesigénica family (familial paroxysmal dyskinesia kinesigenic) - Gen PRRT2.
Quinesigénica paroxysmal dyskinesia family is a disorder characterized by involuntary episodes of abnormal movement ranging from mild to severe. Those affected have episodes of irregular jerking or shaking that are induced by sudden movement. An episode may involve dystonia, chorea, athetosis or ballism. This disease can 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 affected people, an aura immediately precedes the episode. Often the aura is described as a tingling sensation in the affected body part. People familiar with paroxysmal dyskinesia quinesigénica not lose consciousness during an episode and no symptoms between episodes.
In general, individuals with paroxysmal dyskinesia quinesigénica family begin to show signs and symptoms of disease during childhood or adolescence. Typically, these episodes last less than five minutes, the frequency of episodes varies from one per month to 100 per day. In some people, the disease begins in childhood with benign infantile convulsions. These seizures usually develop in the first year of life and cease around 3 years old. When benign infantile convulsions are associated with dyskinesia quinesigénica paroxysmal family, known as infantile convulsions and choreoathetosis (ICCA). In families with ICCA, some individuals develop benign infantile convulsions, some have only paroxysmal dyskinesia quinesigénica family, and others develop both.
This process is due to mutations in the gene PRRT2, located on the short arm of chromosome 16 (16p11.2). This gene encodes transmembrane protein rich in proline 2 (PRRT2). The function of this protein is unknown but is believed to participate in the signaling in the brain. Studies show that interacts with another protein called SNAP25, which is involved in signaling between neurons in the brain. Protein SNAP25 helps control neurotransmitter release.
They described more than 10 mutations in the gene responsible PRRT2 paroxysmal dyskinesia quinesigénica family. The most common genetic change, 649dupC, insert a nucleotide in the gene. Most PRRT2 gene mutations involved in this disease, including 649dupC, leading to an abnormally short protein rapidly decomposes. As a result, affected individuals have less protein than normal PRRT2. It is likely that PRRT2 deficiency affects the function of the protein SNAP25, leading to abnormal signaling between neurons. Although the exact mechanism is unknown, altered neuronal activity could explain the problems of movement characteristic of the disease.
The family paroxysmal dyskinesia quinesigénica is inherited in an autosomal dominant pattern. Autosomal dominant inheritance means that a copy of an altered gene in each cell is sufficient for the disease to be expressed. In most cases, an affected person has a parent with the disease.
Tests performed in IVAMI: in IVAMI perform detection of mutations associated with paroxysmal family quinesigénica dyskinesia, by complete PCR amplification of exons PRRT2 gene, and subsequent sequencing.
Samples recommended: EDTA blood collected for separation of blood leukocytes, or impregnated sample card with dried blood (IVAMI may mail the card to deposit the blood sample).