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
  • Exams and Tests
  • Treatment
    • There are no specific treatments for trisomy 18. Which treatments are used depend on the person's individual condition.

  • Support Groups
  • 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.