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47 XXX syndrome

Other Names for this Disease
  • Triple X syndrome
  • Triple-X chromosome syndrome
  • Triple-X female
  • Triplo X syndrome
  • Trisomy X
More Names
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Is 47 XXX syndrome inherited?

Most cases of 47 XXX syndrome are not inherited. The chromosomal change usually occurs as a random event during the formation of reproductive cells (eggs and sperm). An error in cell division called nondisjunction can result in reproductive cells with an abnormal number of chromosomes. For example, an egg or sperm cell may gain an extra copy of the X chromosome as a result of nondisjunction. If one of these reproductive cells contributes to the genetic makeup of a child, the child will have an extra X chromosome in each of the body's cells. 46,XX/47,XXX mosaicism is also not inherited. It occurs as a random event during cell division in the early development of an embryo. As a result, some of an affected person's cells have two X chromosomes (46,XX), and other cells have three X chromosomes (47,XXX).[1]

Transmission of an abnormal number of X chromosomes from women with 47 XXX syndrome is rare, although it has been reported. Some reports suggest a <5% increased risk for a chromosomally abnormal pregnancy, and other more recent reports suggest that <1% may be more accurate. These risks are separate from the risks of having a chromosomally abnormal pregnancy due to maternal age or any other factors. Furthermore, these risks generally apply only to women with non-mosaic 47 XXX syndrome, as mosaicism may increase the risk of passing on an abnormal number of X chromosomes and potential outcomes.[2] Each individual with 47 XXX syndrome who is interested in learning about their own risks to have a child with a chromosome abnormality or other genetic abnormality should speak with their healthcare provider or a genetics professional.
Last updated: 1/8/2011

  1. Triple X syndrome. Genetics Home Reference. January 2009; Accessed 1/8/2011.
  2. Nicole R Tartaglia, Susan Howell, Ashley Sutherland, Rebecca Wilson, Lennie Wilson. A review of trisomy X (47,XXX). Orphanet Journal of Rare Diseases. May 2010; 11:5-8. Accessed 1/8/2011.