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Definition:
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Trisomy 18 is a genetic disorder in which a person has a third copy of material from chromosome 18, instead of the usual two copies.
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Alternative Names:
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Edwards syndrome
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Causes, incidence, and risk factors:
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Trisomy 18 is a somewhat common syndrome. It is three times more common in girls than boys.
The syndrome occurs when there is extra material from chromosome 18. The extra material affects normal development.
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Signs and tests:
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An exam during pregnancy may show an unusually large uterus and extra amniotic fluid. There may be an unusually small placenta when the baby is born.
A physical exam of the infant may show unusual fingerprint patterns. X-rays may show a short breast bone. Chromosome studies will show trisomy 18, partial trisomy, or translocation.
Other signs include:
There are often signs of congenital heart disease, such as:
Tests may also show kidney problems, including:
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Treatment:
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Treatment of children with trisomy 18 is planned on a case-by-case basis. Which treatments are used depend on the patient's individual condition.
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Expectations (prognosis):
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Half of infants with this condition do not survive beyond the first week of life. Some children have survived to the teenage years, but with serious medical and developmental problems.
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Complications:
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Complications depend on the specific defects and symptoms.
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Calling your health care provider:
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Genetic counseling can help families understand the condition, the risks of inheriting it, and how to care for the patient.
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Prevention:
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Tests can be done during pregnancy to find out if the child has this syndrome.
Genetic testing is recommended for parents who have a child with this syndrome and who want to have more children.
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