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Trisomy 18 (Edwards Syndrome)

Trisomy 18 Facts

  • Trisomy 18 (Edwards syndrome) results from the presence of an extra copy of chromosome 18.
  • Trisomy 18 leads to severe intellectual and physical defects.
  • The prognosis of trisomy 18 is poor. Half of those affected do not live beyond the first week of life and a low percentage of infants with this condition live beyond the first year.
  • Common features of trisomy 18 include a low birth weight; a small jaw and mouth; an abnormally shaped, small head; overlapping fingers and clenched fists; and defects in the heart and other organs.
  • Trisomy 18 occurs on average in 1 out of every 5,000 births.
  • Most fetuses with trisomy 18 die in the prenatal period (prior to delivery).
  • Girls are affected more commonly than boys.

Trisomy 18 Overview

Trisomy 18, also known as Edwards Syndrome, is a severe genetic disorder associated with intellectual disability and abnormalities in many organs. Trisomy 18 was first described in 1960 and results from an additional copy of chromosome 18 (normal cells carry two copies of each chromosome; the term, "trisomy," refers to the presence of three of a given chromosome). Only about 10% of affected infants survive past one year of age, and half of affected infants do not live beyond the first week of life.

Medically Reviewed by a Doctor on 10/28/2014

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