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Genetic and Rare Diseases Information Center (GARD)

Other Names for this Disease
  • 18 trisomy
  • Chromosome 18 trisomy
  • Edwards syndrome
  • Trisomy 16-18 (formerly)
  • Trisomy E (formerly)
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Trisomy 18 is a chromosomal condition associated with severe intellectual disability and abnormalities in many parts of the body. Affected individuals often have a low birth weight; a small, abnormally shaped head; a small jaw and mouth; clenched fists with overlapping fingers; heart defects; and abnormalities of other organs.[1] Due to the presence of several life-threatening medical problems, fifty percent of infants with this condition do not survive beyond the first week of life. Some children have survived to teenage years, but with serious medical and developmental problems.[2] Most cases of Trisomy 18 result from having three copies of chromosome 18 in each cell in the body instead of the usual two copies. Most causes are not inherited and occur by chance.[1]

Last updated: 1/30/2012


  1. Trisomy 18. Genetics Home Reference (GHR). January 2009; Accessed 1/17/2012.
  2. Haldeman-Englert C. Trisomy 18. MedlinePlus. August 2011; Accessed 1/17/2012.
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Basic Information

  • Genetics Home Reference (GHR) contains information on Trisomy 18. This website is maintained by the National Library of Medicine.
  • MedlinePlus was designed by the National Library of Medicine to help you research your health questions, and it provides more information about this topic.
  • The National Organization for Rare Disorders (NORD) is a federation of more than 130 nonprofit voluntary health organizations serving people with rare disorders. Click on the link to view information on this topic.

In Depth Information

  • Medscape Reference provides information on this topic. Click on the link to view this information. You may need to register to view the medical textbook, but registration is free.
  • Orphanet is a European reference portal for information on rare diseases and orphan drugs.  Access to this database is free of charge.
  • PubMed is a searchable database of medical literature and lists journal articles that discuss Trisomy 18. Click on the link to view a sample search on this topic.

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