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

Next Generation Sequencing expression profiling of mitochondrial subunits in men with Klinefelter syndrome.
 

Author(s): Michele Salemi, Laura Cimino, Marika Marino, Rossella Cannarella, Rosita A Condorelli, Corrado Romano, Sandro La Vignera, Aldo E Calogero

Journal:

 

Klinefelter syndrome (KS) is one of the most common sex-chromosome disorders as it affects up to 1 in every 600-1000 newborn males. Men with KS carry one extra X chromosome and they usually present a 47,XXY karyotype, but less frequent variants have also been reported in literature. ...

Last Updated: 31 Dec 1969

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Identification of an AR mutation in Klinefelter syndrome during evaluation for penoscrotal hypospadias.
 

Author(s): Sezer Acar, Hale Tuhan, Elçin Bora, Korcan Demir, Hüseyin Onay, Derya Erçal, Ece Böber, Ayhan Abacı

Journal: Hormones (Athens). 2017 Jul;16(3):313-317.

 

Genital anomalies, ranging from female genitalia to milder degrees of undervirilization, are rarely reported in Klinefelter syndrome, in which a male is classically expected to be born with male external genitalia. Though androgen insensitivity syndrome (AIS) is one of the possible ...

Last Updated: 31 Dec 1969

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Klinefelter Syndrome in Childhood: Variability in Clinical and Molecular Findings
 

Author(s): Neşe Akcan, Şükran Poyrazoğlu, Firdevs Baş, Rüveyde Bundak, Feyza Darendeliler

Journal: J Clin Res Pediatr Endocrinol. 2018 06;10(2):100-107.

 

Klinefelter syndrome (KS) is the most common (1/500–1/1000) chromosomal disorder in males, but only 10% of cases are identified in childhood. This study aimed to review the data of children with KS to assess the age and presenting symptoms for diagnosis, clinical and laboratory ...

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 20 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 Preservation in Cases of Klinefelter Syndrome.
 

Status: Recruiting

Condition Summary: Klinefelter Syndrome

 

Last Updated: 25 May 2018

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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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TESTO: Testosterone Effects on Short-Term Outcomes in Infants With XXY
 

Status: Recruiting

Condition Summary: Klinefelter Syndrome

 

Last Updated: 5 Dec 2017

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