Klinefelter syndrome

Not to be confused with XYY syndrome.
Klinefelter syndrome
Other namesXXY syndrome, Klinefelter's syndrome, Klinefelter-Reifenstein-Albright syndrome
47,XXY karyotype
Pronunciation
  • /ˈklaɪnfɛltər/
SpecialtyMedical genetics
SymptomsVaried; include above average height, weaker muscles, poor coordination, less body hair, breast growth, small testicle size, sexual dysfunction, infertility[1]
ComplicationsInfertility, intellectual disability,[2] autoimmune disorders, breast cancer, venous thromboembolic disease, osteoporosis
Usual onsetAt fertilisation[3]
DurationLifelong
CausesNondisjunction during gametogenesis or in a zygote[4]
Risk factorsOlder age of mother[5]
Diagnostic methodGenetic testing (karyotype)[6]
PreventionNone
TreatmentPhysical therapy, speech and language therapy, Testosterone Supplementation, counseling[7]
PrognosisNearly normal life expectancy[8]
Frequency1 in 500–1000[5][9]
Named afterHarry Klinefelter

Klinefelter syndrome (KS), also known as 47,XXY, is a chromosome anomaly where a male has an extra X chromosome.[10] The complications commonly include infertility and small, poorly functioning testicles (if present). These symptoms are often noticed only at puberty, although this is one of the most common chromosomal disorders. The birth prevalence of KS in the State of Victoria, Australia was estimated to be 223 per 100,000 males.[11] It is named after American endocrinologist Harry Klinefelter, who identified the condition in the 1940s, along with his colleagues at Massachusetts General Hospital.[4][5][12][13]

The syndrome is defined by the presence of at least one extra X chromosome in addition to a Y chromosome, yielding a total of 47 or more chromosomes rather than the usual 46. Klinefelter syndrome occurs randomly. The extra X chromosome comes from the father and mother nearly equally. An older mother may have a slightly increased risk of a child with KS. The syndrome is diagnosed by the genetic test known as karyotyping.[4][6][14][15]

  1. ^ "What are common symptoms of Klinefelter syndrome (KS)?". Eunice Kennedy Shriver National Institute of Child Health and Human Development. 25 October 2013. Archived from the original on 2 April 2015. Retrieved 15 March 2015.
  2. ^ Simonetti L, Ferreira LG, Vidi AC, de Souza JS, Kunii IS, Melaragno MI, et al. (2021). "Intelligence Quotient Variability in Klinefelter Syndrome Is Associated With GTPBP6 Expression Under Regulation of X-Chromosome Inactivation Pattern". Frontiers in Genetics. 12: 724625. doi:10.3389/fgene.2021.724625. PMC 8488338. PMID 34616429.
  3. ^ "Klinefelter syndrome". rarediseases.info.nih.gov. Archived from the original on 15 April 2019. Retrieved 15 April 2019.
  4. ^ a b c Visootsak J, Graham JM (October 2006). "Klinefelter syndrome and other sex chromosomal aneuploidies". Orphanet Journal of Rare Diseases. 1 42. doi:10.1186/1750-1172-1-42. PMC 1634840. PMID 17062147.
  5. ^ a b c "How many people are affected by or at risk for Klinefelter syndrome (KS)?". Eunice Kennedy Shriver National Institute of Child Health and Human Development. 30 November 2012. Archived from the original on 17 March 2015. Retrieved 15 March 2015.
  6. ^ a b "How do health care providers diagnose Klinefelter syndrome (KS)?". Eunice Kennedy Shriver National Institute of Child Health and Human Development. 2012-11-30. Archived from the original on 17 March 2015. Retrieved 15 March 2015.
  7. ^ "What are the treatments for symptoms in Klinefelter syndrome (KS)". Eunice Kennedy Shriver National Institute of Child Health and Human Development. 2013-10-25. Archived from the original on 15 March 2015. Retrieved 15 March 2015.
  8. ^ "Is there a cure for Klinefelter syndrome (KS)?". Eunice Kennedy Shriver National Institute of Child Health and Human Development. 30 November 2012. Archived from the original on 17 March 2015. Retrieved 16 March 2015.
  9. ^ "Klinefelter syndrome". Genetics Home Reference. National Library of Medicine. 30 October 2012. Archived from the original on 15 November 2012. Retrieved 2 November 2012.
  10. ^ "Klinefelter syndrome". National Health Service. 20 February 2023. Archived from the original on 17 January 2024. Retrieved 29 January 2024.
  11. ^ Herlihy, Amy S.; Halliday, Jane L.; Cock, Megan L.; McLachlan, Robert I. (2011). "The prevalence and diagnosis rates of Klinefelter syndrome: an Australian comparison". Medical Journal of Australia. 194 (1): 24–28. doi:10.5694/j.1326-5377.2011.tb04141.x. PMID 21449864.
  12. ^ Cite error: The named reference smedj1986 was invoked but never defined (see the help page).
  13. ^ Visootsak, Jeannie; Graham, John M (2006-10-24). "Klinefelter syndrome and other sex chromosomal aneuploidies". Orphanet Journal of Rare Diseases. 1 (1): 42. doi:10.1186/1750-1172-1-42. ISSN 1750-1172. PMC 1634840. PMID 17062147.
  14. ^ "Klinefelter Syndrome". Mayo Clinic. Archived from the original on 8 September 2020. Retrieved 27 August 2020.
  15. ^ Kanakis, George A.; Nieschlag, Eberhard (September 2018). "Klinefelter syndrome: more than hypogonadism". Metabolism. 86: 135–144. doi:10.1016/j.metabol.2017.09.017. PMID 29382506. S2CID 3702209.
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