Klinefelter Syndrome

National Organization for Rare Disorders, Inc.

It is possible that the main title of the report Klinefelter Syndrome is not the name you expected.

Disorder Subdivisions

  • None

General Discussion

Klinefelter syndrome is a group of chromosomal disorders in males in which one or more extra X chromosomes are present. Males with the classic form of the disorder have one extra X chromosome. Males with variant forms of Klinefelter syndrome have additional X and/or Y chromosomes. The extra X and/or Y chromosome can effect physical and intellectual development. Common physical features may include small testes (hypogonadism), , delayed pubertal development, and breast development (gynecomastia) in late puberty. These features may be associated with low testosterone level and elevated gonadotropin levels.


March of Dimes Birth Defects Foundation
1275 Mamaroneck Avenue
White Plains, NY 10605
Tel: (914)997-4488
Fax: (914)997-4763
Tel: (888)663-4637
Email: Askus@marchofdimes.com
Internet: http://www.marchofdimes.com

870 Miranda Green
Palo Alto, CA 94306
Tel: (360)892-7547
Email: epwatzka@pacbell.net
Internet: http://www.xxxxysyndrome.com/index.htm

Klinefelter Syndrome Association of Canada
1001 Queen Street West
Unit 3
2nd Floor
Ontario, M6J 1H4
Tel: 4165358501
Email: drabinovitch@hotmail.com

NIH/National Institute of Child Health and Human Development
31 Center Dr
Building 31, Room 2A32
Bethesda, MD 20892
Tel: (301)496-5133
Fax: (301)496-7101
Internet: http://www.nichd.nih.gov/

American Association for Klinefelter Syndrome Information and Support
2945 West Farwell Ave.
Chicago, IL 60645-2925
Tel: (773)761-5298
Fax: (773)761-5298
Tel: (888)466-5747
Email: KSinfo@aaksis.org
Internet: http://www.aaksis.org

MUMS National Parent-to-Parent Network
150 Custer Court
Green Bay, WI 54301-1243
Tel: (920)336-5333
Fax: (920)339-0995
Tel: (877)336-5333
Email: mums@netnet.net
Internet: http://www.netnet.net/mums/

Klinefelters Syndrome Support Group of Australia (K.S.S.G)
Kellyville, New South Wales, 2155
Tel: 04 07262398
Email: YATESBECKS@bigpond.com

XXYY Project
PO Box 460265
Aurora, CO 80046-0628
Tel: (303)400-3456
Tel: (888)503-3456
Email: info@xxyysyndrome.org
Internet: http://www.xxyysyndrome.org

Genetic and Rare Diseases (GARD) Information Center
PO Box 8126
Gaithersburg, MD 20898-8126
Tel: (301)251-4925
Fax: (301)251-4911
Tel: (888)205-2311
TDD: (888)205-3223
Email: ordr@od.nih.gov
Internet: http://rarediseases.info.nih.gov/Default.aspx

Madisons Foundation
PO Box 241956
Los Angeles, CA 90024
Tel: (310)264-0826
Fax: (310)264-4766
Email: getinfo@madisonsfoundation.org
Internet: http://www.madisonsfoundation.org

Klinefelter Syndrome & Associates (KS&A)
P.O. Box 461047
Aurora, CO 80046-1047
Tel: (303)400-9040
Fax: (303)400-3454
Tel: (888)999-9428
Email: info@genetic.org
Internet: http://www.genetic.org

For a Complete Report

For a Complete Report

This is an abstract of a report from the National Organization for Rare Disorders, Inc. ® (NORD). A copy of the complete report can be obtained for a small fee by visiting the NORD website. The complete report contains additional information including symptoms, causes, affected population, related disorders, standard and investigational treatments (if available), and references from medical literature. For a full-text version of this topic, see http://www.rarediseases.org/search/rdblist.html

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