How to Say It: TRY-so-mee
Trisomy 13 and trisomy 18 are problems with genes that cause serious birth defects and health problems.
Chromosomes carry our unique DNA. Infants born with trisomy 13 or 18 have three chromosomes where there should only be two.
There are no known risk factors.
Most children will have some, but not all of these symptoms.
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Symptoms can be found both before and after a child is born. Tests may be:
There is no treatment or cure. Most babies have severe physical problems. The condition is managed by making the child comfortable, rather than prolonging life.
Children who survive infancy may need:
There are no known methods to prevent this health problem. After these disorders are diagnosed, parents can decide whether to continue or terminate the pregnancy.
National Organization for Rare Disorders
Support Organization for Trisomy 18, 13, and Related Disorders
Caring for Kids—Canadian Paediatric Society
The Society of Obstetricians and Gynaecologists of Canada
Practice Bulletin No. 163: screening for fetal aneuploidy. Obstet Gynecol. 2016;127(5):e123-e137.
Trisomy 13. EBSCO DynaMed website. Available at: https://www.dynamed.com/condition/trisomy-13. Accessed August 27, 2021.
Trisomy 18. EBSCO DynaMed website. Available at: https://www.dynamed.com/condition/trisomy-18. Accessed August 27, 2021.
Trisomy 18 and 13. Standford Children's Health website. Available at:
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Accessed August 27, 2021.
Last reviewed July 2021 by
EBSCO Medical Review Board
Kari Kuenn, MD
Last Updated: 8/27/2021