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49,XXXXY syndrome
SpecialtyMedical genetics Edit this on Wikidata

49,XXXXY syndrome is an extremely rare aneuploidic sex chromosomal abnormality. It occurs in approximately 1 out of 85,000 to 100,000 males.[1][2]

Signs and symptoms[edit]

Aneuploidy is often fatal, but in this case there is "X-inactivation" where the effect of the additional gene dosage due to the presence of extra X chromosomes is greatly reduced.[3]

Much like Down syndrome, the mental effects of 49,XXXXY syndrome vary. Impaired speech and behavioral problems are typical.[4] Those with 49,XXXXY syndrome tend to exhibit infantile secondary sex characteristics with sterility in adulthood and have some skeletal anomalies. Skeletal anomalies include:

The effects also include:


As its name indicates, a person with the syndrome has one Y chromosome and four X chromosomes on the 23rd pair, thus having forty-nine chromosomes rather than the normal forty-six. As with most categories of aneuploidy disorders, 49,XXXXY syndrome is often accompanied by intellectual disability. It can be considered a form or variant of Klinefelter syndrome (47,XXY).[5][1]

It is genetic but not hereditary, meaning that while the genes of the parents cause the syndrome, there is a small chance of more than one child having the syndrome. The probability of inheriting the disease is about one percent.[3]

The individuals with this syndrome are males, but 49,XXXXX also exists with similar characteristics.[citation needed]



See also[edit]


  1. ^ a b What is XXXXY syndrome? Archived 2008-03-27 at the Wayback Machine Retrieved March 26, 2008.
  2. ^ Visootsak J, Graham JM (2006). "Klinefelter syndrome and other sex chromosomal aneuploidies". Orphanet J Rare Dis. 1: 42. doi:10.1186/1750-1172-1-42. PMC 1634840. PMID 17062147.
  3. ^ a b c Webspawner.com article on 49,XXXXY syndrome Archived 2008-09-14 at the Wayback Machine. Retrieved 26 March 2008.
  4. ^ Visootsak J, Rosner B, Dykens E, Tartaglia N, Graham JM (June 2007). "Behavioral phenotype of sex chromosome aneuploidies: 48,XXYY, 48,XXXY, and 49,XXXXY". Am. J. Med. Genet. A. 143A (11): 1198–203. doi:10.1002/ajmg.a.31746. PMID 17497714.
  5. ^ Cotran, Ramzi S.; Kumar, Vinay; Fausto, Nelson; Nelso Fausto; Robbins, Stanley L.; Abbas, Abul K. (2005). Robbins and Cotran pathologic basis of disease. St. Louis, Mo: Elsevier Saunders. p. 179. ISBN 0-7216-0187-1.

Further reading[edit]

  • Jonathan D. Blumenthal; Eva H. Baker; Nancy Raitano Lee; Benjamin Wade; Liv S. Clasen; Rhoshel K. Lenroot; Jay N. Giedd (2013). "Brain morphological abnormalities in 49,XXXXY syndrome: A pediatric magnetic resonance imaging study". NeuroImage: Clinical. 2: 197–203. doi:10.1016/j.nicl.2013.01.003.

External links[edit]