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Trisomy 18: MedlinePlus Medical Encyclopedia http://www.nlm.nih.gov/medlineplus/ency/article/001661.htm

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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 theusual two copies.

Causes

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 normaldevelopment.

Symptoms

Clenched handsCrossed legsFeet with a rounded bottom (rocker-bottom feet)Low birth weightLow-set earsMental delayPoorly developed fingernailsSmall head (microcephaly)Small jaw (micrognathia)Undescended testicleUnusual shaped chest (pectus carinatum)

Exams and Tests

An exam during pregnancy may show an unusually large uterus and extra amniotic fluid. There may be an unusuallysmall 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:

Hole, split, or cleft in the iris of the eye (coloboma)Separation between the left and right side of the abdominal muscle (diastasis recti)Umbilical hernia or inguinal hernia

There are often signs of congenital heart disease, such as:

Atrial septal defect (ASD)Patent ductus arteriosus (PDA)Ventricular septal defect (VSD)

Tests may also show kidney problems, including:

Horseshoe kidneyHydronephrosisPolycystic kidney

Treatment

Treatment of children with trisomy 18 is planned on a case-by-case basis. Which treatments are used depend on thepatient's individual condition.

Support Groups

Support Organization for Trisomy 18, 13 and Related Disorders (SOFT) -- www.trisomy.org

Trisomy 18: MedlinePlus Medical Encyclopedia http://www.nlm.nih.gov/medlineplus/ency/article/001661.htm

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Trisomy 18 Foundation -- www.trisomy18.orgHope For Trisomy 13 and 18 -- www.hopefortrisomy13and18.org

Outlook (Prognosis)

Half of infants with this condition do not survive beyond the first week of life. Some children have survived to theteenage years, but with serious medical and developmental problems.

Possible Complications

Complications depend on the specific defects and symptoms.

When to Contact a Medical Professional

Genetic counseling can help families understand the condition, the risks of inheriting it, and how to care for thepatient.

Prevention

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.

Alternative Names

Edwards syndrome

Update Date: 7/8/2012

Updated by: Chad Haldeman-Englert, MD,FACMG, Wake Forest School of Medicine, Department of Pediatrics,Section on Medical Genetics, Winston-Salem, NC. Review provided by VeriMed Healthcare Network. Also reviewedby David Zieve, MD, MHA, Medical Director, A.D.A.M. Health Solutions, Ebix, Inc.

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Trisomy 18: MedlinePlus Medical Encyclopedia http://www.nlm.nih.gov/medlineplus/ency/article/001661.htm

3 of 3 08/11/2013 22:44