Chromosomal Abnormalities: Trisomy 13 and 18

(Chromosome 13; Trisomy 13 Complete; Complete Trisomy 13 Syndrome; D Trisomy syndrome; Patau syndrome) ( Chromosome 18; Trisomy 18 Complete; Complete Trisomy 18 Syndrome; Edwards Syndrome; Trisomy E Syndrome)

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.

Risk Factors

There are no known risk factors.


Most children will have some, but not all of these symptoms.

Trisomy 13:

  • Periods of not breathing
  • A vertical slit in the upper lip (cleft lip)
  • An abnormal opening in the roof of the mouth (cleft palate)
  • Extra fingers or toes
  • Problems feeding
  • Feet with large heels
  • Hearing loss
  • Low-set ears that are unusual in shape
  • Low weight at birth
  • Purple and red birthmarks
  • Scalp problems, such as ulcers
  • Problems learning
  • Small eyes or other problems with the eyes, such as a single eye
  • Small head with sloping forehead

Cleft Lip

Cleft lip
Copyright © Nucleus Medical Media, Inc.

Trisomy 18:

  • Periods of not breathing
  • Arms and legs in a bent position
  • A vertical slit in the upper lip
  • An abnormal opening in the roof of the mouth
  • Clenched hands and overlapping fingers
  • Abnormal hands and feet
  • Eye problems
  • Feeding problems
  • Hearing loss
  • Low birth weight
  • Low-set ears that may be unusual in shape
  • Problems learning
  • Small head, with the back of the head larger
  • Small mouth and jaw
  • Webbed neck


Symptoms can be found both before and after a child is born. Tests may be:

Before birth:

  • Pictures may be taken of the fetus. This can be done with ultrasound.
  • Amniocentesis may be done to test the fluid in the uterus.
  • Chorionic villus sampling (CVS) may be done to test cells from the placenta.

After birth:

  • A physical exam will be done.
  • A chromosome analysis may be done using a blood sample.


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:

  • Surgery to correct physical problems
  • Speech therapy
  • Physical therapy
  • Other types of developmental therapy


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: Accessed August 27, 2021.
Trisomy 18. EBSCO DynaMed website. Available at: Accessed August 27, 2021.
Trisomy 18 and 13. Standford Children's Health website. Available at:
...(Click grey area to select URL)
Accessed August 27, 2021.
Last reviewed July 2021 by EBSCO Medical Review Board Kari Kuenn, MD
Last Updated: 8/27/2021

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