Tourette syndrome
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Types and clinical signs
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This is a neurological syndrome characterized by motor and vocal tics (uttering
involuntary sounds and making involuntary movements) and obsessive-compulsive disorder.
The motor tics appear before the vocal tics. Seventy-five percent of the patients
are males, and signs of the disease start to appear between the ages of 2 and 14
years. In 10 - 30% of cases there is a positive family history. About half the patients
have attention disorders that interfere with their studies. According to some authorities,
obesity and alcoholism can also be part of the syndrome.
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Inheritance pattern
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The heredity is most probably multifactorial, although some authorities have suggested
that there is one major gene that is autosomal dominant and that is also affected
by the environment. Other, less prominent genes may also be involved.
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Penetrance
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Partial.
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Associated features that can be demonstrated in tests performed during pregnancy
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There are no known associated defects. This condition cannot be diagnosed in pregnancy.
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What is the risk of recurrence in a subsequent pregnancy?
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The risk that the siblings of an affected individual will also be affected is 10%
if the affected sibling has full Tourrette syndrome or a compulsive disorder, and
20% if the affected sibling has chronic tics.
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Genetic molecular information
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The gene for the disease
This is not known - it is speculated that there are a number of different genes
and an environmental effect.
Location
In one family, a possible location for the gene for Tourrette syndrome was found
on chromosome 11q23. This, however, has not been found in other families. There
may be involvement of other genes including genes situated on chromosomes 4 and
8.
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Genetic testing
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Diagnostic testing
This is not available. In families with affected members, a study for mapping the
gene can be considered. See information sheet: Indirect testing for genetic markers
in a family with one or more patients in the family - when there are a number of
different genes that can each cause the disease - the gene or most of the genes
have not yet been located / identified / mapped - autosomal dominant disease.
Carrier testing
As for diagnostic testing.
Fetal testing
As for diagnostic testing.
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