Skip to Content
Home > Wellness > Health Library > Trisomy 18
Trisomy 18 is a genetic condition related to the presence of an
extra chromosome 18 caused by a problem that occurs when cells divide in the
egg, sperm, or fertilized egg. The extra chromosome causes the fetus to develop
abnormally with a number of physical and mental problems.
18 is also called Edward's syndrome. It is the second most common trisomy
condition. (Down syndrome is the most common.) A fetus with trisomy 18 has
three copies of chromosome 18 in each cell.
Trisomy 18 can be identified during
pregnancy. Doctors can do prenatal tests and fetal ultrasounds to screen for
problems, and they can do chromosome tests to diagnose trisomy 18.
Many fetuses with trisomy 18 do not survive to birth, but some are born
and live a couple of months to a couple of years. Babies born with trisomy 18
can have heart and kidney problems, a small
head with low-set ears, a chest with an unusual shape, and crossed legs. They
also have severe intellectual disability.
Current as of:
November 20, 2015
Sarah Marshall, MD - Family Medicine & Siobhan M. Dolan, MD, MPH - Reproductive Genetics
To learn more about Healthwise, visit Healthwise.org.
© 1995-2016 Healthwise, Incorporated. Healthwise, Healthwise for every health decision, and the Healthwise logo are trademarks of Healthwise, Incorporated.
I Want To...
Our interactive Decision Points guide you through making key health decisions by combining medical information with your personal information.
You'll find Decision Points to help you answer questions about:
Get started learning more about your health!
Our Interactive Tools can help you make smart decisions for a healthier life. You'll find personal calculators and tools for health and fitness, lifestyle checkups, and pregnancy.
Feeling under the weather?
Use our interactive symptom checker to evaluate your symptoms and determine appropriate action or treatment.