위키백과, 우리 모두의 백과사전.
47,XYY는 유전되는 것은 아니지만, 일반적으로 정자 세포의 형성 기간 동안 무작위로 발생한다. 비분열(비분리)로 불리는, 감수 분열 2단계의 염색체 분리 오류가 발생하면 Y 염색체가 하나 더 생기는 정자 세포가 생산될 수 있다. 이 비정상적인 정자 세포들 가운데 하나가 아이의 유전적 구성에 기여하는 경우 아이는 몸 세포 각각에 Y 염색체가 하나 더 붙게 된다.
- Graham, Gail E.; Allanson, Judith E.; Gerritsen, Jennifer A. (2007). 〈Sex chromosome abnormalities〉. Rimoin, David L.; Connor, J. Michael.; Pyeritz, Reed E.; Korf, Bruce R. (eds.). 《Emery and Rimoin's principles and practice of medical genetics》 5판. Philadelphia: Churchill Livingstone Elsevier. 1038–1057쪽. ISBN 0-443-06870-4.
This sex chromosome aneuploidy is not characterized by distinct physical features and, because there does not appear to be recognizable pattern of neurodevelopment or behavioral characteristics, the use of the term syndrome may be inappropriate. Males with an extra Y chromosome are phenotypically normal and most never come to medical attention.
Pubertal development, testicular histology, and spermatogenesis are most often normal.
It appears that XY pairing and recombination occur normally in 47,XYY, the extra Y chromosome being lost during spermatogenesis, so that many XYY men have fathered chromosomally normal children. It has generally been observed that reproductive risks for males with 47,XYY are no higher than for euploid males, despite the fact that in situ hybridization studies demonstrated a lower frequency of single Y-bearing sperm than expected and a variably higher rate of disomic XX, XY and YY spermatozoa in males with 47,XYY.
Population-based studies have demonstrated that intellectual abilities tend to be slightly lower than those of siblings and matched controls and that boys with an extra Y chromosome are more likely to require educational help. However, intelligence is usually well within the normal range.
During school age, learning disabilities requiring educational intervention are present in approximately 50% and are as responsive to therapy as they are in children with normal chromosomes. Expressive and receptive language delays and reading disorders are common.
- Milunsky, Jeff M. (2010). 〈Prenatal diagnosis of sex chromosome abnormalities〉. Milunsky, Aubrey; Milunsky, Jeff M. (eds.). 《Genetic disorders and the fetus: diagnosis, prevention and treatment》 6판. Oxford: Wiley-Blackwell. 273–312쪽. ISBN 1-4051-9087-6.
The addition of a Y chromosome to a normal male chromosome constitution does not produce a discernible phenotype. Males with 47,XYY cannot be characterized by discriminating physical or behavioral features. The first diagnosis of this condition, therefore, was a karyotypic and not a phenotypic discovery.
Pubertal development is normal and these men are usually fertile.
- Jacobs, Patricia A. (2006). 《The discovery and history of Trisomy X and XYY syndrome》. DVD 02. Sacramento: KS&A.
Oxford Data Base — XYY total ascertainment: ~ 3% — 934 XYYs (801 XYYs + 133 XYY mosaics) in Britain (population 60 million)
- Robinson, David O.; Jacobs, Patricia A. (November 1, 1999). “The origin of the extra Y chromosome in males with a 47,XYY karyotype” (PDF). 《Hum Mol Genet》 8 (12): 2205–2209. doi:10.1093/hmg/8.12.2205. PMID 10545600.
- 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 7 international newborn screening studies of sex chromosome abnormalities.
- XYY syndrome page on the Contact a Family Directory website
- has background and medical information and details of UK support groups