Klinefelter syndrome

Common Name(s)

Klinefelter syndrome, Klinefelter Syndrome (47, XXY)

Klinefelter syndrome is a chromosome disorder that affects a male’s physical and cognitive development. Symptoms of Klinefelter syndrome in babies may include muscle weakness; delayed ability to crawl, sit or walk (gross motor development); and delayed speech. Symptoms in boys and teenagers may include being taller than average, delayed puberty, small penis, enlarged breast tissue, weak bones, low energy levels, shyness, difficulty expressing feelings, problems with learning, and difficulty focusing. Symptoms in men may include trouble having children (infertility), small testicles and penis, being taller than average, weak bones, decreased facial and body hair, enlarged breast tissue, and decreased sex drive. Signs and symptoms of Klinefelter syndrome vary. In fact, some boys go undiagnosed until adulthood.

Typically, people have 46 chromosomes (23 pairs) in all of their cells. 22 of these pairs are similar in males and females. However one pair, called the sex chromosomes, is different in males and females. Females have two X chromosomes for their sex chromosome pair (XX), while males have an X and a Y sex chromosome pair (XY). Klinefelter syndrome is caused by extra X chromosomes in males, which is typically just one extra X (XXY), but can be more. The extra X chromosomes occur as a random event during the formation of the egg or sperm. Klinefelter syndrome is not an inherited condition.

A doctor, typically a geneticist, can see signs of Klinefelter syndrome on a physical exam by evaluating a male’s genitals and chest. The diagnosis is typically confirmed with a hormone test that shows low testosterone and a genetic test that shows one or more extra X chromosomes. Unfortunately, there is no cure for Klinefelter syndrome. Treatment consists of testosterone replacement, speech therapy, physical therapy, and fertility treatment. If you or your son have Klinefelter syndrome, talk to your doctor to discuss the best treatment plan.

Source: Advocacy organizations associated with the condition.

 

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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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: 4 Mar 2015

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AIS-DSD Support Group

The AIS-DSD Support Group is a compassionate community of individuals, families and allies collaborating to promote better lives and informed decision-making through advancement of knowledge so no one will face a diagnosis alone.

Last Updated: 12 Jan 2015

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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: 29 Apr 2015

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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: 31 Mar 2015

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General Support Organizations

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How do you compare to others with this condition?

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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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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: 4 Mar 2015

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AIS-DSD Support Group

The AIS-DSD Support Group is a compassionate community of individuals, families and allies collaborating to promote better lives and informed decision-making through advancement of knowledge so no one will face a diagnosis alone.

http://www.aisdsd.org

Last Updated: 12 Jan 2015

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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: 29 Apr 2015

View Details
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/

Last Updated: 31 Mar 2015

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General Support Organizations

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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 78 free, full-text research articles on human participants. First 3 results:

A possible means of countering the underdiagnosis of Klinefelter Syndrome.
 

Author(s): Steffi Werler, Joachim Wistuba

Journal: Asian J. Androl.. ;16(5):785.

 

Last Updated: 28 Oct 2014

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Comorbidity between Klinefelter syndrome and diaphragmatic hernia. A case report.
 

Author(s): Carolina Melendez Valdez, Stephan Philip Leonhardt Altmayer, Adyr Eduardo Virmond Faria, Aline Weiss, Jorge Alberto Bianchi Telles, Paulo Renato Krall Fell, Luciano Vieira Targa, Paulo Ricardo Gazzola Zen, Rafael Fabiano Machado Rosa

Journal: Sao Paulo Med J. 2014 ;132(5):311-3.

 

Intrathoracic cystic lesions have been diagnosed in a wide variety of age groups, and the increasing use of prenatal imaging studies has allowed detection of these defects even in utero.

Last Updated: 4 Sep 2014

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Pseudomembranous trigonitis in a male with Klinefelter syndrome: a case report and evidence of a hormonal etiology.
 

Author(s): Derrick W Q Lian, Fay X Li, Caroline C P Ong, C H Kuick, Kenneth T E Chang

Journal:

 

Klinefelter syndrome is a clinical syndrome with a distinct 47, XXY karyotype. Patients are characterized by a tall eunuchoid stature, small testes, hypergonotrophic hypogonadism, gynecomastia, learning difficulties and infertility. These patients have also been found to have raised ...

Last Updated: 17 Jul 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 19 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: 8 Jun 2015

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Fertility Preservation in Cases of Klinefelter Syndrome.
 

Status: Recruiting

Condition Summary: Klinefelter Syndrome

 

Last Updated: 15 Jan 2015

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Fertility Assessment in Patients With Klinefelter Syndrome
 

Status: Not yet recruiting

Condition Summary: Klinefelter Syndrome

 

Last Updated: 29 May 2015

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