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

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

Investigation of AZF microdeletions in patients with Klinefelter syndrome.
 

Author(s): L X Li, H Y Dai, X P Ding, Y P Zhang, X H Zhang, H Y Ren, Z Y Chen

Journal:

 

We investigated azoospermia region microdeletions in male infertility patients with Klinefelter syndrome (KFS), as well as the association between azoospermia symptoms in patients with KFS and Y chromosome microdeletion polymorphisms. A total of 111 cases with male infertility confirmed ...

Last Updated: 4 Dec 2015

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Clinical characteristics of men with non-mosaic Klinefelter syndrome in northeastern China: implications for genetic counseling.
 

Author(s): M Zhang, H-T Fan, H-S Zheng, Q-S Zhang, S-Q Feng, R-W Li

Journal:

 

Klinefelter syndrome (KS) is the most common genetic cause of male infertility. Widespread development in assisted reproductive technology has provided non-mosaic KS patients with the opportunity of having biological children. Testosterone replacement therapy and micro-dissection ...

Last Updated: 24 Sep 2015

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Genome-wide site-specific differential methylation in the blood of individuals with Klinefelter syndrome.
 

Author(s): Emily S Wan, Weiliang Qiu, Jarrett Morrow, Terri H Beaty, Jacqueline Hetmanski, Barry J Make, David A Lomas, Edwin K Silverman, Dawn L DeMeo

Journal: Mol. Reprod. Dev.. 2015 May;82(5):377-86.

 

Klinefelter syndrome (KS) (47 XXY) is a common sex-chromosome aneuploidy with an estimated prevalence of one in every 660 male births. Investigations into the associations between DNA methylation and the highly variable clinical manifestations of KS have largely focused on the supernumerary ...

Last Updated: 20 May 2015

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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:

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: 17 Feb 2016

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Klinefelter Syndrome and medical treatment: hypogonadism and beyond.
 

Author(s): Simon Chang, Anne Skakkebæk, Claus Højbjerg Gravholt

Journal: Hormones (Athens). ;14(4):531-48.

 

Klinefelter syndrome (KS), though described more than 70 years ago, still imposes significant diagnostic challenges. Based on data from epidemiological studies, KS is associated with increased morbidity and mortality. Although the pathophysiology and etiology behind these observations ...

Last Updated: 10 Feb 2016

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Testis Development and Fertility Potential in Boys with Klinefelter Syndrome.
 

Author(s): Shanlee M Davis, Alan D Rogol, Judith L Ross

Journal: Endocrinol. Metab. Clin. North Am.. 2015 Dec;44(4):843-65.

 

Klinefelter syndrome (KS) is the leading genetic cause of primary hypogonadism and infertility in men. The clinical phenotype has expanded beyond the original description of infertility, small testes, and gynecomastia. Animal models, epidemiologic studies, and clinical research of ...

Last Updated: 16 Nov 2015

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Symptoms, Diagnosis, and Treatment

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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: 5 Aug 2016

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Fertility Assessment in Patients With Klinefelter Syndrome
 

Status: Recruiting

Condition Summary: Klinefelter Syndrome

 

Last Updated: 3 Oct 2016

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Body Composition in Infants With Klinefelter Syndrome and Effects of Testosterone Treatment
 

Status: Recruiting

Condition Summary: Klinefelter Syndrome

 

Last Updated: 27 Oct 2016

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