Tourette syndrome ... (Tourette syndrome) - Gen SLITRK1.
Tourette's syndrome is an involuntary complex disorder characterized by repetitive, sudden movements, and called "tics". Tics usually appear in childhood, and their intensity varies with time. In most cases, tics become milder and less frequent in late adolescence and adults.
Tourette's syndrome involves both motor tics, and vocal or phonic tics. Some are simple motor tics and involve a single muscle group. Simple motor tics, such as rapid blinking, shrug, or twitching of the nose, are often the first signs of Tourette syndrome. Motor tics can also be complex (involving various muscle groups), such as jumping, kicking or rotate. Vocal tics, which usually appear later than motor tics, and can be simple or complex. Simple vocal tics include grunts, and hoarseness. More complex vocalizations include repeating others' words (echolalia) or repeat the words themselves (palilalia). It is possible, although rare, involuntary use of obscene or inappropriate language (coprolalia), among people with Tourette syndrome. In addition to frequent tics, people with this disorder are at risk of associated problems including hyperactivity disorder attention deficit disorder (ADHD), obsessive-compulsive disorder (OCD), anxiety, depression and sleep problems.
A variety of genetic and environmental factors likely play a role to give the Tourette syndrome. Most of these factors are unknown, and are being studied risk factors before and after birth that can contribute to this complex disorder. It is believed that tics can be triggered by changes in the neurotransmitters that are responsible for the production and control of voluntary movements.
In addition, mutations have been identified that affect SLITRK1 gene, located on the long arm of chromosome 13 (13q31.1) in a small number of people affected. This gene encodes a protein that is active in the brain. This protein probably plays a role in the development of nerve cells, including growth of specialized extensions (axons and dendrites) that allow each nerve cell to communicate with neighboring cells. One of the identified mutations (del1264C) deletes one base pair of the gene. This mutation results in the encoding of an abnormally short, nonfunctional version SLITRK1 protein. Another mutation changes one base pair in a DNA region near the gene. This change is likely to interfere with the protein coding. However, it is unclear how mutations in the gene SLITRK1 can lead to this condition. Most people with Tourette 's syndrome have a mutation in the gene SLITRK1. Because mutations have been described so few people with this disorder, it has not confirmed the association of gene SLITRK1 with Tourette syndrome. It is suspected that changes in other genes that have not been identified, also associated with Tourette's syndrome.
The inheritance pattern of Tourette syndrome is unclear. Although the characteristics of this disorder can be grouped into families, many genetic and environmental factors are likely to be involved. Among the relatives of an affected person, it is more difficult to predict who may be at risk of developing the syndrome. Previously, it was thought that has an autosomal dominant inheritance, suggesting that a mutated copy of a gene in every cell would be sufficient to cause disease. Several decades of research have shown that this is not the case. Almost all cases of Tourette 's syndrome are probably caused by a variety of genetic and environmental factors, rather than by changes in a single gene.
Tests in IVAMI: in IVAMI perform detection of mutations associated with Tourette syndrome, by the complete PCR amplification of exons delos SLITRK1 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).