XYY syndrome: Wikis


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XYY syndrome
Classification and external resources

Y chromosome
ICD-10 Q98.5
ICD-9 758.8
DiseasesDB 33038
MeSH D014997

XYY syndrome is an aneuploidy (abnormal number) of the sex chromosomes in which a human male receives an extra Y chromosome, giving a total of 47 chromosomes instead of the more usual 46. This produces 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][2]


Physical traits

Most often, the extra Y chromosome causes no unusual physical features or medical problems. 47,XYY boys have an increased growth velocity during earliest childhood, with an average final height approximately 7 cm above expected final height.[3] 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.[4]

Testosterone levels (prenatally and postnatally) are normal in 47,XYY males.[5] Most 47,XYY males have normal sexual development and usually have normal fertility. Since XYY is not characterized by distinct physical features, the condition is usually detected only 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][6][7][8][9][10][11][12][13] In comparison, a national survey of US children conducted in 2004 for the CDC found that 10% of all boys had a learning disability.[14]

As with 47,XXY boys and 47,XXX girls, IQ scores of 47,XYY boys average 10–15 points below their siblings.[6][9][7][11][12] For context, this amount of variation—an average difference of 12 IQ points—often occurs naturally between children in the same family.[6][15]

The Denver Family Development Study led by Arthur Robinson[16] found that 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.[17] For the 11 of 14 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.[17]

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.[7][9][13] Aggression is not seen more frequently in 47,XYY males.[1][6][7][9][10][12]


47,XYY is not inherited, but usually occurs as a random event during the formation of sperm cells. An error in chromosome separation during anaphase II (of meiosis II) 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.[13][18]

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.[13][18]


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][9][11]

First case

The first published report of a man with a 47,XYY karyotype was by 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 daughter with Down syndrome.[19][20]

47,XYY was the last of the common sex chromosome aneuploidies to be discovered, two years after the discoveries of 47,XXY, 45,X, and 47,XXX in 1959. Even the much less common 48,XXYY had been discovered in 1960, a year before 47,XYY. Screening for these X chromosome aneuploidies was possible by noting the presence or absence of "female" sex chromatin bodies (Barr bodies) in the nuclei of interphase cells in buccal smears, a technique developed a decade before the first reported sex chromosome aneuploidy.[21]

An analogous technique to screen for Y chromosome aneuploidies by noting supernumerary "male" sex chromatin bodies was not developed until 1970, a decade after the first reported sex chromosome aneuploidy.[22][23] In December 1969, Lore Zech at the Karolinska Institute in Stockholm first reported intense fluorescence of the AT-rich distal half of the long arm of the Y chromosome in the nuclei of metaphase cells treated with quinacrine mustard.[24] Four months later, in April 1970, Peter L. Pearson and Martin Bobrow at the MRC Population Genetics Unit in Oxford and Canino G. Vosa at the University of Oxford reported fluorescent "male" sex chromatin bodies in the nuclei of interphase cells in buccal smears treated with quinacrine dihdyrochloride.[25]

The myth

In 1965, the geneticist Patricia Jacobs and colleagues published their finding that a disproportionately large number of men in a maximum-security prison—7 out of 197—had the XYY karyotype.[26] This started a theory that "a high percentage of all men who carry X-Y-Y chromosomes have strong criminal tendencies"[27] and even that "the extra Y chromosome seems to cause aggressive or violent behavior".[28] The theory gained great public attention in 1968 after false reports that the infamous multiple murderer Richard Speck was 47,XYY and that his lawyer would argue he thus deserved a lesser punishment. (Speck was actually 46,XY, and his lawyer had no intention of mentioning XYY.)[29][30] Time ran a story[31] as did Newsweek,[32] and another Newsweek story followed two years later[33] The results of 47,XYY were called "supermale syndrome",[34] and some linked the supposed criminal predisposition to excessive maleness.[35] Associated legal and ethical issues elicited considerable discussion.[36]

However, others pointed out that the original studies were flawed[37][38] and the link to violence was "a dangerous myth".[39] The opposition focused particularly on a longitudinal study that screened baby boys in Boston, with the intention of tracking those with XYY throughout their lives. Opponents argued that the study had ethical problems: the parents had not been properly informed of the purpose of the study, and the investigators had to either withhold the karyotypes from the parents or risk that the boys would be stigmatized and possibly become antisocial because of a self-fulfilling prophecy. As no treatment for any symptoms was foreseeable, the study would be of limited value to the subjects. After considerable publicity, the study was canceled.[30][40] Opponents of the cancelation such as Bernard Davis were "appalled" when, as they saw it, a public-relations campaign stopped scientific research that scientists considered valuable.[41]

Though the idea that an extra Y chromosome caused crime was debunked, it appeared in popular culture. Kenneth Royce wrote a successful novel, The X. Y. Y. Man, whose hero is a burglar struggling with his innate criminal tendencies; Royce published seven more books about the character, and Granada Television produced a total of 13 episodes based on the books in the summers of 1976 and 1977. An Italian horror film, The Cat o' Nine Tails, depicted a criminal who killed to keep his XYY karyotype secret.[42] In Robert A. Heinlein's science-fiction novel I Will Fear No Evil, a character says that another character "is mean. An XYY. Committed his first murder at eleven."[43] From another perspective, a 1971 episode of the British television show Doomwatch, "By the Pricking of My Thumbs...", dealt with prejudice against people with the XYY syndrome.[44] As late as 1992, the film Alien 3 included a prison planet for violent men called "double Y-chromos".[45]

See also


  1. ^ a b c d Graham, Gail E.; Allanson, Judith E.; Gerritsen, Jennifer A. (2007). "Sex chromosome abnormalities". in Rimoin, David L.; Connor, J. Michael.; Pyeritz, Reed E.; Korf, Bruce R. (eds.). Emery and Rimoin's Principles and Practice of Medical Genetics (5th ed.). Philadelphia: Churchill Livingstone Elsevier. pp. 1038–1057. ISBN 0443068704. 
  2. ^ Jacobs, Patricia (March 3–5, 2006). "The genetics of XXY, Trisomy X and XYY syndromes: an overview". National Conference on Trisomy X and XYY, UC Davis M.I.N.D. Institute,. DVD 02. Sacramento: KS&A. http://www.genetic.org/knowledge/support/store/C210/#Genetics. 
  3. ^ Nielsen, Johannes (1998). "How is height growth?". XYY Males. An Orientation. The Turner Center, Aarhus Psychiatric Hospital, Risskov, Denmark. http://www.aaa.dk/TURNER/ENGELSK/XYY.HTM#height. Retrieved 2008-01-11. 
  4. ^ Plewig, Gerd; Kligman, Albert M. (2000). Acne and Rosacea (3rd ed.). Philadelphia: Springer-Verlag. p. 377. ISBN 3540667512. 
  5. ^ Ratcliffe SG, Read G, Pan H, Fear C, Lindenbaum R, Crossley J (September 1994). "Prenatal testosterone levels in XXY and XYY males". Horm Res 42 (3): 106–109. doi:10.1159/000184157. PMID 7995613. 
  6. ^ a b c d Guy's Hospital Clinical Genetics Department (2001, 2005). "The XYY Condition". Scottish Genetics Education Network (ScotGEN). http://www.scotgen.org.uk/documents/XYY%20for%20parents.pdf. Retrieved 2009-09-12. 
  7. ^ a b c d Linden MG, Bender BG, Robinson A (June 1, 2002). "Genetic counseling for sex chromosome abnormalities". Am J Med Genet 110 (1): 3–10. doi:10.1002/ajmg.10391. PMID 12116264. http://www3.interscience.wiley.com/journal/93513415/abstract. 
  8. ^ Gardner, R.J. McKinlay; Sutherland, Grant R. (2004). Chromosome Abnormalities and Genetic Counseling (3rd ed.). Oxford: Oxford University Press. pp. 29–30, 42, 199, 207, 257, 263, 393, 424–430. ISBN 0195149602. 
  9. ^ a b c d e Milunsky, Jeff M. (2004). "Prenatal Diagnosis of Sex Chromosome Abnormalities". in Milunsky, Aubrey (ed.). Genetic Disorders and the Fetus : Diagnosis, Prevention, and Treatment (5th ed.). Baltimore: Johns Hopkins University Press. pp. 297–340. ISBN 0801879280. 
  10. ^ a b Beltz, Carin Lea (2005). "XYY Syndrome". in Narins, Brigham (ed.). The Gale Encyclopedia of Genetic Disorders (2nd ed.). Detroit: Thomson Gale. pp. 1369–1371. ISBN 1414403658. 
  11. ^ a b c Firth, Helen V.; Hurst, Jane A.; Hall, Judith G. (2005). Oxford Desk Reference: Clinical genetics. Oxford: Oxford University Press. pp. 498–499. ISBN 0192628968. 
  12. ^ a b c Nussbaum, Robert L.; McInnes, Roderick R.; Willard, Huntington F. (2007). Thompson & Thompson Genetics in Medicine (7th ed.). Philadelphia: Saunders Elsevier. pp. 105–107. ISBN 1416030808. 
  13. ^ a b c d National Library of Medicine (January 3, 2010). "Genetics Home Reference: 47,XYY syndrome". Bethesda: National Library of Medicine. http://ghr.nlm.nih.gov/condition=47xyysyndrome. Retrieved 2010-01-13. 
  14. ^ Bloom B, Dey AN (February 2006). "Summary health statistics for U.S. children: National Health Interview Survey, 2004". Vital Health Stat (National Center for Health Statistics) 10 (227): 1–85. PMID 16532761. http://www.cdc.gov/nchs/data/series/sr_10/sr10_227.pdf. 
  15. ^ Scarr, Sandra; Deater-Deckard, Kirby (1997). "Family effects on individual differences in development". in Luthar, Suniya S. (ed.). Developmental psychopathology: perspectives on adjustment, risk, and disorder. Cambridge: Cambridge University Press. p. 119. ISBN 0521477158. 
  16. ^ Robinson A (April 1990). "Living history: An autobiography of Arthur Robinson". Am J Med Genet 35 (4): 475–480. doi:10.1002/ajmg.1320350406. PMID 2185631. http://www3.interscience.wiley.com/journal/110515769/abstract. 
  17. ^ a b Linden MG, Bender BG (June 1, 2002). "Fifty-one prenatally diagnosed children and adolescents with sex chromosome abnormalities". Am J Med Genet 110 (1): 11–18. doi:10.1002/ajmg.10394. PMID 12116265. http://www3.interscience.wiley.com/journal/93513431/abstract. 
  18. ^ a b Robinson DO, Jacobs PA (November 1, 1999). "The origin of the extra Y chromosome in males with a 47,XYY karyotype". Hum Mol Genet 8 (12): 2205–2209. doi:10.1093/hmg/8.12.2205. PMID 10545600. http://hmg.oxfordjournals.org/cgi/reprint/8/12/2205.pdf. 
  19. ^ Sandberg AA, Koepf GF, Ishihara T, Hauschka TS (August 26, 1961). "An XYY human male". Lancet 278 (7200): 488–489. doi:10.1016/S0140-6736(61)92459-X. PMID 13746118. 
  20. ^ Hauschka TS, Hasson JE, Goldstein MN, Koepf GF, Sandberg AA (March 1962). "An XYY man with progeny indicating familial tendency to non-disjunction". Am J Hum Genet 14: 22–30. PMID 13905424. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1932182/pdf/ajhg00555-0023.pdf. 
  21. ^ Barr ML, Bertram EG (1949). "A Morphological Distinction between Neurones of the Male and Female, and the Behaviour of the Nucleolar Satellite during Accelerated Nucleoprotein Synthesis". Nature 163 (4148): 676–677. doi:10.1038/163676a0. PMID 18120749. 
  22. ^ . (June 6, 1970). "In Pursuit of the Y Chromosome". Nature 226 (5249): 897. doi:10.1038/226897a0. PMID 4192294. http://www.nature.com/nature/journal/v226/n5249/pdf/226897a0.pdf. 
  23. ^ . (February 6, 1971). "Dyeing the Y Chromosome". Lancet 297 (7693): 275–276. doi:10.1016/S0140-6736(71)91008-7. 
  24. ^ Zech L (December 1969). "Investigation of Metaphase Chromosomes with DNA-binding Flurochromes". Exp Cell Res 58 (2–3): 463. http://www.sciencedirect.com/science?_ob=PublicationURL&_tockey=%23TOC%236791%231969%23999419997%23535233%23FLP%23&_cdi=6791&_pubType=J&view=c&_auth=y&_acct=C000050221&_version=1&_urlVersion=0&_userid=10&md5=9adcfa112e875932c708e8fbe4829245. 
  25. ^ Pearson PL, Bobrow M, Vosa CG (April 4, 1970). "Technique for Identifying Y Chromosomes in Human Interphase Nuclei". Nature 226 (5240): 78–80. doi:10.1038/226078a0. PMID 4190810. http://www.nature.com/nature/journal/v226/n5240/abs/226078a0.html. 
  26. ^ Jacobs, Patricia A.; Brunton, Muriel; Melville, Marie M.; Brittain, R. P.; McClemont, W. F. (1965). "Aggressive Behavior, Mental Sub-Normality and the XYY Male". Nature 208: 1351–1352. doi:10.1038/2081351a0. http://www.nature.com/nature/journal/v208/n5017/pdf/2081351a0.pdf. Retrieved 2010-03-06.  Subscription required.
  27. ^ Katzir-Katchalsky, A. (October 1972). "An Israeli Scientist's Approach to Human Values". Bulletin of the Atomic Scientists 28 (8): 19–23. http://books.google.com/books?id=4gsAAAAAMBAJ&pg=PA19#v=onepage&q=&f=false. Retrieved 2010-02-08. 
  28. ^ Brierley, John Keith (1970). Biology and the Social Crisis: A Social Biology for Everyman. Fairleigh Dickinson University Press. p. 201. ISBN 0-8386-7719-3. http://books.google.com/books?id=DK3SUtsA6JYC&pg=PA201. Retrieved 2010-02-08.  A footnote with no matching asterisk in the text seems to mean that this behavior was supposedly directed against property, not people.
  29. ^ Green, Jeremy (1985). "Media Sensationalism and Science: The Case of the Criminal Chromosome". in Shinn, Terry; Whitley, Richard. Expository Science. Springer: Sociology of the Sciences Yearbook IX. pp. 139–161. ISBN 90-277-1831-8. http://books.google.com/books?id=ATpe1PJf3CoC&pg=PA139#v=onepage&q=&f=false. Retrieved 2010-02-08. 
  30. ^ a b Gould, Stephen Jay (1996). The Mismeasure of Man (2nd edition ed.). W. W. Norton. p. 174. ISBN 0-393-31425-1. http://books.google.com/books?id=WTtTiG4eda0C&pg=PA174. Retrieved 2010-02-08. 
  31. ^ "Chromosomes and Crime". Time: 45–46. 1968-05-03. 
  32. ^ "Born Bad?". Newsweek 70: 87. 1968-05-6. 
  33. ^ "Congenital Criminals?". Newsweek 75: 98–99. 1970. 
  34. ^ Scientific Proceedings in Summary Form. American Psychiatric Association. 1969. p. 12. 
  35. ^ Jarvik, L. F.; Klodin, V.; Matsuyama, S. S. "Human Aggression and the Extra Y Chromosome". American Psychologist 1973. https://my.apa.org/apa/idm/login.seam?ERIGHTS_TARGET=http%3A%2F%2Fpsycnet.apa.org%2Fjournals%2Famp%2F28%2F8%2F674.pdf&AUTHENTICATION_REQUIRED=true. "The Y chromosome is the male-determining chromosome; therefore, it should come as no surprise that an extra Y chromosome can produce an individual with heightened masculinity, evinced by characteristics such as unusual tallness, increased fertility (although most XYYs do not have children, some have produced as many as 10), and powerful aggressive tendencies".  As noted above, the claim of increased fertility proved false as well as that of aggressive tendencies.
  36. ^ Pronko, Nicholas Henry (1973). Panorama of Psychology (second edition ed.). Brooks/Cole. p. 100. ISBN 0818500735. 
  37. ^ Winfree, L. Thomas, Jr.; Abadinsky, Howard (2009). Understanding Crime: Essentials of Criminological Theory. Cengage Learning. p. 79. http://books.google.com/books?id=seWtlZnW6xkC&pg=PA79#v=onepage&q=&f=false. Retrieved 2010-03-06. 
  38. ^ Arieti, Silvano (1974). American Handbook of Psychiatry, Volume Three. Basic Books. p. 262. 
  39. ^ Beckwith, Jon; King, Jonathan. "The XYY syndrome: a dangerous myth". New Scientist 64: 474–476. 
  40. ^ Suzuki, David; Knudtson, Peter (1989). Genethics: The Clash Between the New Genetics and Human Values. Harvard University Press. pp. 152–157. ISBN 0-674-34565-7. http://books.google.com/books?id=mPbsLEwkWWIC&pg=PA145#v=onepage&q=&f=false. Retrieved 2010-03-06. 
  41. ^ Callahan, Daniel (2006). What Price Better Health? Hazards of the Research Imperative. pp. 167–168. http://books.google.com/books?id=Q4uc7ZNRBNIC&pg=PA167#v=onepage&q=&f=false. Retrieved 2010-03-06. 
  42. ^ Beckwith, Jonathan R. (2002). Making Genes, Making Waves: A Social Activist in Science. Harvard University Press. p. 121. ISBN 0-674-00928-2. http://books.google.com/books?id=1DrLuK30CMcC&pg=PA121#v=onepage&q=&f=false. Retrieved 2010-02-08. 
  43. ^ Heinlein, Robert A. (1970). I Will Fear No Evil. Putnam. p. 27.  The character with 47,XYY is described as "little" (p. 32), which would be unusual.
  44. ^ Fulton, Roger (1990). The Encyclopedia of TV Science Fiction. Boxtree. p. 153. ISBN 1852832770. 
  45. ^ Washington, Harriet A. (2006). Medical Apartheid: The Dark History of Experimentation on Black Americans from Colonial Times to the Present. Random House. p. 282. ISBN 0-385-50993-6. http://books.google.com/books?id=4ZmJvC3f-m0C&pg=PA282#v=onepage&q=&f=false. Retrieved 2010-02-08. 

External links

  • Guy's Hospital Clinical Genetics Department (2001, 2005). The XYY Condition. Scottish Genetics Education Network (ScotGEN)
    • XYY information leaflet based on work of Dr. Ratcliffe, a pediatrician and geneticist who led the largest of 8 international newborn screening studies of sex chromosome abnormalities.
  • 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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