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.

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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 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: 27 Nov 2012

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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.

Logo
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 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: 27 Nov 2012

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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

View Details
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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 68 free, full-text research articles on human participants. First 3 results:

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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Social attention, affective arousal and empathy in men with Klinefelter syndrome (47,XXY): evidence from eyetracking and skin conductance.
 

Author(s): Sophie van Rijn, Marjolein Barendse, Stephanie van Goozen, Hanna Swaab

Journal:

 

Individuals with an extra X chromosome (Klinefelter syndrome) are at risk for problems in social functioning and have an increased vulnerability for autism traits. In the search for underlying mechanisms driving this increased risk, this study focused on social attention, affective ...

Last Updated: 13 Jan 2014

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

Author(s): Reinhard Niemann

Journal: Dtsch Arztebl Int. 2013 Oct;110(40):675.

 

Last Updated: 29 Oct 2013

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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 16 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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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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Testicular function and fertility in men with Klinefelter syndrome: a review.
 

Author(s): L Aksglaede, A Juul

Journal:

 

Klinefelter syndrome, 47,XXY (KS), is the most frequent sex chromosome aberration in males, affecting 1 in 660 newborn boys. The syndrome is characterized by testicular destruction with extensive fibrosis and hyalinization of the seminiferous tubules resulting in small testes, hypergonadotropic ...

Last Updated: 18 Mar 2013

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Symptoms, Diagnosis, and Treatment

There are currently no related results available in GeneReviews.

There are currently no related results available in Genetic Testing Registry.

 
 
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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: 4 Jan 2013

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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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