Skip to main content

Health Encyclopedia

Search the Health Encyclopedia

Trisomy 18

Definition

Trisomy 18 is a genetic disorder in which a person has a third copy of material from chromosome 18, instead of the usual 2 copies.

Alternative Names

Edwards syndrome

Causes

Trisomy 18 occurs in 1 in 6,000 live births. It is 3 times more common in girls than boys.

The syndrome occurs when there is extra material from chromosome 18. The extra material affects normal development.

Symptoms

Symptoms may include:

Exams and Tests

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. The chromosome abnormality may be present in every cell or present in only a certain percentage of the cells (called mosaicism). Studies may also show part of the chromosome in some cells. Rarely, part of the chromosome 18 becomes attached to another chromosome. This is called translocation.

Other signs include:

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

Tests may also show kidney problems, including:

Treatment

There are no specific treatments for trisomy 18. Which treatments are used depend on the person's individual condition.

Support Groups

Support groups include:

Outlook (Prognosis)

Half of infants with this condition do not survive beyond the first week of life. Nine out of 10 children will die by 1 year of age. Some children have survived to the teenage 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 the person.

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.

References

Bacino CA, Lee B. Cytogenetics. In: Kliegman RM, Stanton BF, St. Geme JW, Schor NF, eds. Nelson Textbook of Pediatrics. 20th ed. Philadelphia, PA: Elsevier; 2016:chap 81.

Review Date:8/1/2015
Reviewed By:Chad Haldeman-Englert, MD, FACMG, Fullerton Genetics Center, Asheville, NC. Review provided by VeriMed Healthcare Network. Also reviewed by David Zieve, MD, MHA, Isla Ogilvie, PhD, and the A.D.A.M. Editorial team.

The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition. A licensed medical professional should be consulted for diagnosis and treatment of any and all medical conditions. Call 911 for all medical emergencies. Links to other sites are provided for information only -- they do not constitute endorsements of those other sites. © 1997-A.D.A.M., Inc. Any duplication or distribution of the information contained herein is strictly prohibited.

adam.com

The Agency for Health Care Administration (Agency) and this website do not claim the information on, or referred to by, this site is error free. This site may include links to websites of other government agencies or private groups. Our Agency and this website do not control such sites and are not responsible for their content. Reference to or links to any other group, product, service, or information does not mean our Agency or this website approves of that group, product, service, or information.

Additionally, while health information provided through this website may be a valuable resource for the public, it is not designed to offer medical advice. Talk with your doctor about medical care questions you may have.

Health
Outcome Data

No data available for this condition/procedure.

Read More

Images

Health Encyclopedia

More Features

We Appreciate Your Feedback!
1. Did you find this information useful?
         Yes
         No
2. Would you recommend this website to family and friends?
         Yes
         No