XYY syndrome
From Wikipedia, the free encyclopedia
| ICD-10 | Q98.5 | |
|---|---|---|
| ICD-9 | 758.8 | |
| DiseasesDB | 33038 | |
| MeSH | C23.550.210.815.970 | |
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.<ref name=allanson>Allanson, Judith E.; Graham, Gail E. (2002). “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, 4th ed., London: Churchill-Livingstone, pp. 1184-1201. ISBN 0-443-06434-2.</ref>
Contents |
[edit] Effects
[edit] 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.<ref name=plewig>Plewig, Gerd; Kligman, Albert M. (2000). Acne and Rosacea, 3rd ed., Philadelphia: Springer-Verlag, p. 377. ISBN 3-540-66751-2.</ref>
Testosterone levels (prenatally and postnatally) are normal in 47,XYY males.<ref name=ratcliffe>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.</ref> 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.
[edit] Behavioral characteristics
47,XYY boys have an increased risk of learning difficulties (in up to 50%) and delayed speech and language skills.<ref name=allanson/><ref name=guys>Guy's Hospital Clinical Genetics Department (2001). The XYY Condition. Retrieved on 2006-09-27.</ref><ref name=gardner>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 0-19-514960-2.</ref><ref name=milunsky>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: The Johns Hopkins University Press, pp. 297-340. ISBN 0-8018-7928-0.</ref><ref name=nussbaum>Nussbaum, Robert L.; McInnes, Roderick R.; Willard, Huntington F. (2004). Thompson & Thompson Genetics in Medicine, Revised Reprint, 6th ed., Philadelphia: W.B. Saunders, pp. 172-174. ISBN 0-7216-0244-4.</ref><ref name=beltz>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 1-4144-0365-8.</ref><ref name=firth>Firth, Helen V.; Hurst, Jane A.; Hall, Judith G. (2005). Oxford Desk Reference: Clinical genetics. Oxford: Oxford University Press, pp. 498-499. ISBN 0-19-262896-8.</ref><ref name=ghr>National Library of Medicine (2006). Genetics Home Reference: 47,XYY syndrome. Retrieved on 2006-08-28.</ref> For context, surveys report 10% of all boys had a learning disability.<ref name=bloom>Bloom B, Dey AN (2006). Summary health statistics for U.S. children: National Health Interview Survey, 2004. Vital Health Stat 10 (227): 1-85. PMID 16532761.</ref>
As with 47,XXY boys and 47,XXX girls, IQ scores of 47,XYY boys average 10–15 points below their siblings.<ref name=guys/><ref name=milunsky/><ref name=nussbaum/><ref name=firth/> 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.<ref name=guys/> 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.<ref name=linden>Linden MG, Bender BG (2000). Fifty-one prenatally diagnosed children and adolescents with sex chromosome abnormalities. Am J Med Genet 110 (1). PMID 12116265.</ref>
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.<ref name=milunsky/><ref name=ghr/> Aggression is not seen more frequently in 47,XYY males.<ref name=allanson/><ref name=guys/><ref name=milunsky/><ref name=nussbaum/><ref name=beltz/>
[edit] 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.<ref name=ghr/><ref name=robinson>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.</ref>
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.<ref name=ghr/><ref name=robinson/>
[edit] 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.<ref name=allanson/><ref name=milunsky/><ref name=firth/>
[edit] 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.<ref name=sandberg>Sandberg AA, Koepf GF, Ishihara T, Hauschka TS (1961). An XYY human male. Lancet 278 (7200): 488-9. PMID 13746118.</ref>
[edit] See also
- Klinefelter's syndrome
- Triple X syndrome
- Turner syndrome
- 48,XXYY syndrome
- The XYY Man
- Genetics Influencing Aggression (historical scientifically discredited assumptions about XYY)
[edit] References
[edit] External links
- Guy's Hospital Clinical Genetics Department (2001). The XYY Condition
- 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 purchasebg:XYY синдром
cs:XYY syndrom de:XYY-Syndrom hu:XYY-szindróma pl:Nadsamiec pt:Síndrome XYY fi:XYY-syndrooma tr:XYY sendromu zh:XYY-三體
