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XYY syndrome

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XYY syndrome
SpecialtyMedical genetics Edit this on Wikidata
Frequency0.05%, 0.01%

XYY syndrome is an aneuploidy (specifically a trisomy) of the sex chromosomes in which a human male receives an extra Y chromosome, producing a 47,XYY karyotype.

Some medical geneticists question whether the term "syndrome" is appropriate for this condition because its phenotype is normal and the vast majority (an estimated 97% in the UK) of 47,XYY males do not know their karyotype.[1]

Effects

Physical traits

Most often, this chromosomal change causes no unusual physical features or medical problems. 47,XYY boys and men are usually taller than average and several centimeters taller than their parents and siblings. Severe acne was noted in a very few early case reports, but dermatologists specializing in acne now doubt the existence of a relationship with 47,XYY.[2]

Testosterone levels (prenatally and postnatally) are normal in 47,XYY males.[3] Most 47,XYY males have normal sexual development and usually have normal fertility. Since there are no distinct physical characteristics, the condition usually is only detected during genetic analysis for another reason.

Behavioral characteristics

47,XYY boys have an increased risk of learning difficulties (in up to 50%) and delayed speech and language skills.[1][4][5][6][7][8][9][10] For context, surveys report 10% of all boys had a learning disability.[11]

As with 47,XXY boys and 47,XXX girls, IQ scores of 47,XYY boys average 10–15 points below their siblings.[4][6][7][9] It is important to realize that this amount of variation—an average difference of 12 IQ points—occurs naturally between children in the same family.[4] In 14 prenatally diagnosed 47,XYY boys from high socioeconomic status families, IQ scores available for 6 boys ranged from 100–147 with a mean of 120. For 11 boys with siblings, in 9 instances their siblings were stronger academically, but in one case they were performing equal to and in another case superior to their brothers and sisters.[12]

Developmental delays and behavioral problems are also possible, but these characteristics vary widely among affected boys and men, are not unique to 47,XYY and are managed no differently than in 46,XY males.[6][10]

In popular culture, including the TV series The XYY Man and the movie Alien 3, XYY males have been depicted as aggressive and even criminal. However, this is not supported by medical studies.[1][4][6][7][8]

Cause

47,XYY is not inherited, but usually occurs as a random event during the formation of sperm cells. An error in cell division during metaphase I called nondisjunction can result in sperm cells with an extra copy of the Y chromosome. If one of these atypical sperm cells contributes to the genetic makeup of a child, the child will have an extra Y chromosome in each of the body's cells.[10][13]

In some cases, the addition of an extra Y chromosome results from nondisjunction during cell division during a post-zygotic mitosis in early embryonic development. This can produce 46,XY/47,XYY mosaics.[10][13]

Incidence

About 1 in 1,000 boys are born with a 47,XYY karyotype. The incidence of 47,XYY is not affected by advanced paternal (or maternal) age.[1][6][9]

First case

The first published report of a man with a 47,XYY karyotype was by Dr. Avery A. Sandberg and colleagues at Roswell Park Memorial Institute in Buffalo, New York in 1961. It was an incidental finding in a normal 44-year-old, 6 ft. [183 cm] tall man of average intelligence who was karyotyped because he had a Down syndrome daughter.[14]

See also

References

  1. ^ a b c d Allanson, Judith E.; Graham, Gail E. (2002). "Sex chromosome abnormalities". In in Rimoin, David L.; Connor, J. Michael.; Pyeritz, Reed E.; Korf, Bruce R. (eds.) (ed.). Emery and Rimoin's Principles and Practice of Medical Genetics (4th ed. ed.). London: Churchill-Livingstone. pp. pp. 1184-1201. ISBN 0-443-06434-2. {{cite book}}: |edition= has extra text (help); |editor= has generic name (help); |pages= has extra text (help); Unknown parameter |quotes= ignored (help)CS1 maint: multiple names: authors list (link)
  2. ^ Plewig, Gerd; Kligman, Albert M. (2000). Acne and Rosacea (3rd ed. ed.). Philadelphia: Springer-Verlag. pp. p. 377. ISBN 3-540-66751-2. {{cite book}}: |edition= has extra text (help); |pages= has extra text (help)CS1 maint: multiple names: authors list (link)
  3. ^ Ratcliffe SG, Read G, Pan H, Fear C, Lindenbaum R, Crossley J (1994). "Prenatal testosterone levels in XXY and XYY males". Horm Res. 42 (3): 106–9. PMID 7995613. {{cite journal}}: Unknown parameter |quotes= ignored (help)CS1 maint: multiple names: authors list (link)
  4. ^ a b c d Guy's Hospital Clinical Genetics Department (2001). "The XYY Condition" (PDF). Retrieved 2006-09-27.
  5. ^ Gardner, R.J. McKinlay; Sutherland, Grant R. (2004). Chromosome Abnormalities and Genetic Counseling (3rd ed. ed.). Oxford: Oxford University Press. pp. pp. 29-30, 42, 199, 207, 257, 263, 393, 424–430. ISBN 0-19-514960-2. {{cite book}}: |edition= has extra text (help); |pages= has extra text (help)CS1 maint: multiple names: authors list (link)
  6. ^ a b c d e Milunsky, Jeff M. (2004). "Prenatal Diagnosis of Sex Chromosome Abnormalities". In in Milunsky, Aubrey (ed.) (ed.). Genetic Disorders and the Fetus : Diagnosis, Prevention, and Treatment (5th ed. ed.). Baltimore: The Johns Hopkins University Press. pp. pp. 297-340. ISBN 0-8018-7928-0. {{cite book}}: |edition= has extra text (help); |editor= has generic name (help); |pages= has extra text (help); Unknown parameter |quotes= ignored (help)
  7. ^ a b c Nussbaum, Robert L.; McInnes, Roderick R.; Willard, Huntington F. (2004). Thompson & Thompson Genetics in Medicine, Revised Reprint (6th ed. ed.). Philadelphia: W.B. Saunders. pp. pp. 172-174. ISBN 0-7216-0244-4. {{cite book}}: |edition= has extra text (help); |pages= has extra text (help)CS1 maint: multiple names: authors list (link)
  8. ^ a b Beltz, Carin Lea (2005). "XYY Syndrome". In in Narins, Brigham (ed.) (ed.). The Gale Encyclopedia of Genetic Disorders (2nd ed. ed.). Detroit: Thomson Gale. pp. pp. 1369-1371. ISBN 1-4144-0365-8. {{cite book}}: |edition= has extra text (help); |editor= has generic name (help); |pages= has extra text (help); Unknown parameter |quotes= ignored (help)
  9. ^ a b c Firth, Helen V.; Hurst, Jane A.; Hall, Judith G. (2005). Oxford Desk Reference: Clinical genetics. Oxford: Oxford University Press. pp. pp. 498-499. ISBN 0-19-262896-8. {{cite book}}: |pages= has extra text (help)CS1 maint: multiple names: authors list (link)
  10. ^ a b c d National Library of Medicine (2006). "Genetics Home Reference: 47,XYY syndrome". Retrieved 2006-08-28.
  11. ^ Bloom B, Dey AN (2006). "Summary health statistics for U.S. children: National Health Interview Survey, 2004" (PDF). Vital Health Stat. 10 (227). National Center for Health Statistics: 1–85. PMID 16532761. {{cite journal}}: Unknown parameter |quotes= ignored (help)
  12. ^ Linden MG, Bender BG (2000). "Fifty-one prenatally diagnosed children and adolescents with sex chromosome abnormalities". Am J Med Genet. 110 (1). PMID 12116265. {{cite journal}}: Unknown parameter |pagse= ignored (help); Unknown parameter |quotes= ignored (help)
  13. ^ a b Robinson DO, Jacobs PA (1999). "The origin of the extra Y chromosome in males with a 47,XYY karyotype". Hum Mol Genet. 8 (12): 2205–9. PMID 10545600. {{cite journal}}: Unknown parameter |quotes= ignored (help)
  14. ^ Sandberg AA, Koepf GF, Ishihara T, Hauschka TS (1961). "An XYY human male". Lancet. 278 (7200): 488–9. PMID 13746118. {{cite journal}}: Unknown parameter |quotes= ignored (help)CS1 maint: multiple names: authors list (link)
  • Nielsen, Johannes (1998). XYY Males. An Orientation. The Turner Center, Aarhus Psychiatric Hospital, Risskov, Denmark.
    • XYY information booklet by Dr. Nielsen, a psychiatrist and geneticist who led the longest running of 8 international newborn screening studies of sex chromosome abnormalities.
  • Unique (http://www.rarechromo.org)
    • has XYY information leaflets available to members and available for purchase to non-members
  • Klinefelter Syndrome & Associates (http://www.genetic.org)
    • has 2006 Trisomy X and XYY National Conference binders and DVDs available for purchase
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