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

Klinefelter syndrome comorbidities linked to increased X chromosome gene dosage and altered protein interactome activity.
 

Author(s): Kirstine Belling, Francesco Russo, Anders B Jensen, Marlene D Dalgaard, David Westergaard, Ewa Rajpert-De Meyts, Niels E Skakkebæk, Anders Juul, Søren Brunak

Journal: Hum. Mol. Genet.. 2017 04;26(7):1219-1229.

 

Klinefelter syndrome (KS) (47,XXY) is the most common male sex chromosome aneuploidy. Diagnosis and clinical supervision remain a challenge due to varying phenotypic presentation and insufficient characterization of the syndrome. Here we combine health data-driven epidemiology and ...

Last Updated: 31 Dec 1969

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Autism Spectrum Disorder in Males with Sex Chromosome Aneuploidy: XXY/Klinefelter Syndrome, XYY, and XXYY.
 

Author(s): Nicole R Tartaglia, Rebecca Wilson, Judith S Miller, Jessica Rafalko, Lisa Cordeiro, Shanlee Davis, David Hessl, Judith Ross

Journal: J Dev Behav Pediatr. 2017 Apr;38(3):197-207.

 

Neurodevelopmental concerns in males with sex chromosome aneuploidy (SCA) (XXY/Klinefelter syndrome, XYY, XXYY) include symptoms seen in autism spectrum disorder (ASD), such as language impairments and social difficulties. We aimed to: (1) evaluate ASD characteristics in research ...

Last Updated: 31 Dec 1969

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[Craniopharyngioma and Klinefelter syndrome during the pubertal transition: A diagnostic challenge].
 

Author(s): Yamile Mocarbel, Graciela Arébalo de Cross, Marie C Lebrethon, Albert Thiry, Albert Beckersd, Hernan Valdes-Socin

Journal: Arch Argent Pediatr. 2017 04;115(2):e104-e107.

 

Craniopharyngioma is the most common pituitary tumor in childhood. It can compromise the pubertal development because of its evolution or treatment. Syndrome of Klinefelter is the most common cause of hipergonadotrophic hypogonadism in males. The concomitant presentation of both entities ...

Last Updated: 31 Dec 1969

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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 23 free, full-text review articles on human participants. First 3 results:

Klinefelter syndrome (KS): genetics, clinical phenotype and hypogonadism.
 

Author(s): M Bonomi, V Rochira, D Pasquali, G Balercia, E A Jannini, A Ferlin,

Journal: J. Endocrinol. Invest.. 2017 Feb;40(2):123-134.

 

Klinefelter Syndrome (KS) is characterized by an extreme heterogeneity in its clinical and genetic presentation. The relationship between clinical phenotype and genetic background has been partially disclosed; nevertheless, physicians are aware that several aspects concerning this ...

Last Updated: 31 Dec 1969

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Advances in the Interdisciplinary Care of Children with Klinefelter Syndrome.
 

Author(s): Shanlee Davis, Susan Howell, Rebecca Wilson, Tanea Tanda, Judy Ross, Philip Zeitler, Nicole Tartaglia

Journal: Adv Pediatr. 2016 08;63(1):15-46.

 

Last Updated: 31 Dec 1969

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Mediastinal mixed germ cell tumor in an infertile male with Klinefelter syndrome:A case report and literature review.
 

Author(s): Dinesh Pradhan, Lileswar Kaman, Jasreman Dhillon, Sambit K Mohanty

Journal: J Cancer Res Ther. ;11(4):1034.

 

Klinefelter syndrome (KS) is a well-documented abnormality of the sex chromosome, with an incidence of 1 in 600 newborn males. It is characterized by a 47, XXY or a mosaic karyotype, hypergonadotrophic hypogonadism, infertility, reduced body hair, gynecomastia, and tall stature. Different ...

Last Updated: 31 Dec 1969

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Clinical Trial Information This information is provided by ClinicalTrials.gov

Fertility Assessment in Patients With Klinefelter Syndrome
 

Status: Recruiting

Condition Summary: Klinefelter Syndrome

 

Last Updated: 20 Oct 2017

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Fertility Preservation in Cases of Klinefelter Syndrome.
 

Status: Recruiting

Condition Summary: Klinefelter Syndrome

 

Last Updated: 29 May 2017

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Thrombosis and Neurocognition in Klinefelter Syndrome
 

Status: Recruiting

Condition Summary: Klinefelter Syndrome; Thrombosis

 

Last Updated: 18 Jan 2018

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