Klinefelter syndrome

Common Name(s)

Klinefelter syndrome, Klinefelter Syndrome (47, XXY)

Klinefelter syndrome (KS) is a condition that may be present in an individual that has two X chromosomes and one Y chromosome (47, XXY); usually, males have one X and one Y (XY) and females have two X chromosomes (XX). Some individuals with a 47, XXY chromosome finding may have no obvious signs or symptoms of KS while others may have several features and varying degrees of cognitive, social, behavioral, and learning difficulties. Because features may not be apparent until mid to late adolescence, the term “Klinefelter syndrome” is often reserved for affected adolescents and adults. Although the vast majority of boys with KS identify as males, some individuals develop atypical gender identities. In adulthood, individuals with Klinefelter syndrome may have primary hypogonadism (decreased testosterone production), small testes, enlarged breast tissue (gynecomastia), tall stature, and/or other features. The vast majority of males with KS are infertile, but many produce sperm and may be able to conceive with assisted reproduction. Treatment varies among individuals and may include testosterone therapy; however, this therapy may not be appropriate for all individuals.
 

Advocacy and Support Organizations

 

Condition Specific Organizations

Following organizations serve the condition "Klinefelter syndrome" for support, advocacy or research.

Klinefelter Syndrome & Associates, Inc.

KS&A’s mission is to help individuals with one or more extra X and/or Y chromosomes and their families lead fuller and more productive lives. http://www.genetic.org/About/MissionStatement.aspx

Last Updated: 1 Nov 2014

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American Association for Klinefelter Syndrome Information & Support

The mission of the American Association for Klinefelter Syndrome Information & Support is the education, support, research and understanding of 47XXY and its variants, collectively known as Klinefelter Syndrome.

Last Updated: 2 Nov 2012

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Beyond XXY, Inc.

Beyond XXY,Inc., is a U.S. nonprofit support, information, and advocacy organization. Our mission is to be a resource for the health and welfare of 47, XXYs and variants.

Last Updated: 22 Aug 2013

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Klinefelter's Syndrome Association of Canada

To support and facilitate the dissemination of information to those with Klinefelter Syndrome and their families

Last Updated: 24 Nov 2009

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The Focus Foundation

The Focus Foundation is dedicated to helping children and families affected by X & Y Variations, Dyslexia, and/or Developmental Dyspraxia. The Focus Foundation believes that through increased awareness, early identification and syndrome-specific treatment, children with these conditions can reach their full potential.

Last Updated: 19 Feb 2013

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Unique - Understanding Chromosome Disorders

Our mission is to inform, support and alleviate the isolation of anyone affected by a rare chromosome disorder and to raise public awareness.

Last Updated: 21 Jul 2014

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Advocacy and Support Organizations

 

Condition Specific Organizations

Following organizations serve the condition "Klinefelter syndrome" for support, advocacy or research.

Klinefelter Syndrome & Associates, Inc.

KS&A’s mission is to help individuals with one or more extra X and/or Y chromosomes and their families lead fuller and more productive lives. http://www.genetic.org/About/MissionStatement.aspx

http://www.genetic.org

Last Updated: 1 Nov 2014

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American Association for Klinefelter Syndrome Information & Support

The mission of the American Association for Klinefelter Syndrome Information & Support is the education, support, research and understanding of 47XXY and its variants, collectively known as Klinefelter Syndrome.

http://www.aaksis.org

Last Updated: 2 Nov 2012

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Beyond XXY, Inc.

Beyond XXY,Inc., is a U.S. nonprofit support, information, and advocacy organization. Our mission is to be a resource for the health and welfare of 47, XXYs and variants.

http://xxyintersex.com/index.html

Last Updated: 22 Aug 2013

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Klinefelter's Syndrome Association of Canada

To support and facilitate the dissemination of information to those with Klinefelter Syndrome and their families

Last Updated: 24 Nov 2009

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The Focus Foundation

The Focus Foundation is dedicated to helping children and families affected by X & Y Variations, Dyslexia, and/or Developmental Dyspraxia. The Focus Foundation believes that through increased awareness, early identification and syndrome-specific treatment, children with these conditions can reach their full potential.

http://www.thefocusfoundation.org/FF/index.php

Last Updated: 19 Feb 2013

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Unique - Understanding Chromosome Disorders

Our mission is to inform, support and alleviate the isolation of anyone affected by a rare chromosome disorder and to raise public awareness.

http://www.rarechromo.org

Last Updated: 21 Jul 2014

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Scientific Literature

Articles from the PubMed Database

Research articles describe the outcome of a single study. They are the published results of original research.
The terms "Klinefelter syndrome" returned 71 free, full-text research articles on human participants. First 3 results:

Homicide and Klinefelter syndrome: a complex interaction.
 

Author(s): Stéphane Richard-Devantoy, Fabrice Jollant, Anne-Isabelle Bouyer-Richard, Jean-Paul Lhuillier, Philip Gorwood

Journal: Rev Bras Psiquiatr. ;36(2):153-6.

 

Several studies have shown an association between homicide and sexual chromosomal abnormalities, but data are still lacking regarding Klinefelter syndrome.

Last Updated: 21 May 2014

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Klinefelter syndrome - a general practice perspective.
 

Author(s): Elyssia Bourke, Amy Herlihy, Pamela Snow, Sylvia Metcalfe, David Amor

Journal: Aust Fam Physician. ;43(1):38-41.

 

Klinefelter syndrome (KS) is a common genetic condition affecting one in 450 men, but is only diagnosed in fewer than half of those affected.

Last Updated: 24 Feb 2014

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Epigenomic and transcriptomic signatures of a Klinefelter syndrome (47,XXY) karyotype in the brain.
 

Author(s): Joana Viana, Ruth Pidsley, Claire Troakes, Helen Spiers, Chloe Cy Wong, Safa Al-Sarraj, Ian Craig, Leonard Schalkwyk, Jonathan Mill

Journal: Epigenetics. 2014 Apr;9(4):587-99.

 

Klinefelter syndrome (KS) is the most common sex-chromosome aneuploidy in humans. Most affected individuals carry one extra X-chromosome (47,XXY karyotype) and the condition presents with a heterogeneous mix of reproductive, physical and psychiatric phenotypes. Although the mechanism(s) ...

Last Updated: 18 Apr 2014

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Reviews from the PubMed Database

Review articles summarize what is currently known about a disease. They discuss research previously published by others.
The terms "Klinefelter syndrome" returned 17 free, full-text review articles on human participants. First 3 results:

Management of Klinefelter syndrome during transition.
 

Author(s): Inge Gies, David Unuane, Brigitte Velkeniers, Jean De Schepper

Journal: Eur. J. Endocrinol.. 2014 Aug;171(2):R67-77.

 

Klinefelter syndrome (KS) is the most common sex chromosomal disorder in males. Key findings in older adolescents and young men are small testes with variable hypo-androgenism, but almost universal azoospermia, most frequently in combination with a history of learning difficulties ...

Last Updated: 25 Jun 2014

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The role of hypogonadism in Klinefelter syndrome.
 

Author(s): Christian Høst, Anne Skakkebæk, Kristian A Groth, Anders Bojesen

Journal: Asian J. Androl.. ;16(2):185-91.

 

Klinefelter syndrome (KS) (47, XXY) is the most abundant sex-chromosome disorder, and is a common cause of infertility and hypogonadism in men. Most men with KS go through life without knowing the diagnosis, as only 25% are diagnosed and only a few of these before puberty. Apart from ...

Last Updated: 20 Mar 2014

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Klinefelter syndrome: the commonest form of hypogonadism, but often overlooked or untreated.
 

Author(s): Eberhard Nieschlag

Journal: Dtsch Arztebl Int. 2013 May;110(20):347-53.

 

Klinefelter syndrome (KS) with the karyotype 47,XXY is one of the commonest types of congenital chromosomal disorder in males, with an incidence of 0.1% to 0.2% of newborn male infants. It causes hypogonadism and infertility. Until now, however, only about one-quarter of all persons ...

Last Updated: 4 Jul 2013

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Symptoms, Diagnosis, and Treatment

There are currently no related results available in GeneReviews.

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Clinical Trial Information This information is provided by ClinicalTrials.gov

Study of Psychological and Motor Effects of Testosterone in Adolescents With XXY/Klinefelter Syndrome
 

Status: Recruiting

Condition Summary: Klinefelter Syndrome; XXY Syndrome

 

Last Updated: 1 Dec 2014

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Fertility Preservation in Cases of Klinefelter Syndrome.
 

Status: Recruiting

Condition Summary: Klinefelter Syndrome

 

Last Updated: 15 Jan 2014

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Subcapsular Orchiectomy in Men With Klinefelter Syndrome
 

Status: Recruiting

Condition Summary: Klinefelter Syndrome

 

Last Updated: 13 Dec 2012

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