Definition

Trisomy 13 and trisomy 18 are genetic disorders that cause serious birth defects and health problems. The majority of babies born with these syndromes die by age one, although some survive longer.

Because babies with trisomy 13 or 18 have a short life expectancy, parents should speak with their child’s doctor about whether life-sustaining measures are appropriate.

If you have had a child with trisomy 13 or 18 and plan to have another child, contact your doctor about genetic counseling.

Causes

Chromosomes carry genetic information. Infants born with trisomy 13 or 18 have three chromosomes where there should only be two.

Risk Factors

A risk factor is something that increases your chance of getting a disease or condition. There are no known ways that parents can cause or prevent their child from being born with trisomy 13 or 18. There may be some association with advanced maternal age.

Symptoms

The symptoms of trisomy 13 and 18 vary. Most children will have some, but not all of the symptoms listed below. If your child is born with any of these symptoms, do not assume it is due to trisomy 13 or trisomy 18. These symptoms may be caused by other health conditions. Talk to your physician about your concerns.

Symptoms of trisomy 13:

  • Abnormalities of brain development
  • Abnormally shaped uterus, in girls
  • Apnea—prolonged periods when there is no breathing
  • Cleft lip —a vertical slit in the upper lip (more common than in trisomy 18)
  • Cleft palate —an abnormal opening in the roof of the mouth (more common than in trisomy 18)
  • Extra fingers or toes
  • Feeding difficulties
  • Feet with prominent heels
  • Hearing loss
  • Heart defects
  • Hernias —bulging of tissue or organs through a weak spot or opening in a muscle wall
  • Kidney problems
  • Low-set ears, unusual in shape
  • Low birth weight
  • Purplish-red birthmarks
  • Scalp abnormalities
  • Seizures
  • Severe mental retardation
  • Small eyes or other abnormalities of the eyes (including a single eye)
  • Small head with sloping forehead
  • Testes that fail to descend, in boys

Cleft Lip

Cleft lip
© 2009 Nucleus Medical Art, Inc.

Symptoms of trisomy 18:

  • Apnea—prolonged periods when there is no breathing
  • Arms and legs in a bent position
  • Cleft Lip—a vertical slit in the upper lip
  • Cleft Palate—an abnormal opening in the roof of the mouth
  • Clenched hands and overlapping fingers
  • Deformed hands and feet
  • Eye problems
  • Feeding problems
  • Hearing loss
  • Heart defects
  • Hernias—bulging of tissue or organs through a weak spot or opening in a muscle wall
  • Kidney abnormalities
  • Low birth weight
  • Low-set ears that may be deformed
  • Mental deficiency
  • Scoliosis —a curving of the spine
  • Shortened breastbone
  • Small head, with the back of the head prominent
  • Small mouth and jaw
  • Testes that fail to descend
  • Underdeveloped fingernails

Diagnosis

Trisomy 13 and 18 can be diagnosed both before and after birth. Tests may include the following:

  • Before birth:
    • Amniocentesis —analysis of the cells in the amniotic fluid (the liquid that surrounds the baby during pregnancy)
    • Ultrasound —a test that uses sound waves to examine the baby
    • CVS (chorionic villus sampling)—analysis of a sample of cells from the placenta
  • After birth:
    • A physical exam
    • A chromosome analysis, done by using a blood sample from the baby

Treatment

There is no specific treatment or cure for trisomy 13 or trisomy 18. Since most babies born with trisomy 13 or 18 have very severe physical problems, treatment may focus on making the child comfortable, rather than prolonging life. Talk to your doctor about whether life-prolonging measures are appropriate for your child.

Children who survive infancy may require the following:

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

Prevention

There are no known ways to prevent trisomy 13 or trisomy 18. Once these disorders are diagnosed, parents can decide whether to continue or terminate the pregnancy. If you have concerns, talk to a genetic counselor when deciding to have children.