Triplo X Syndrome

National Organization for Rare Disorders, Inc.

It is possible that the main title of the report Triplo X Syndrome is not the name you expected. Please check the synonyms listing to find the alternate name(s) and disorder subdivision(s) covered by this report.


  • Triple X Syndrome
  • 47,XXX Syndrome
  • 47,XXX Karyotype
  • 47,XXX Chromosome Constitution
  • Trisomy X

Disorder Subdivisions

  • None

General Discussion

Triplo X Syndrome is a chromosomal abnormality that affects females. Females normally have two X chromosomes; however, those with Triplo X Syndrome carry three X chromosomes (trisomy X) in the nuclei of body cells. No specific pattern of symptoms and malformations (phenotype) has been found to be associated with this abnormal chromosomal make-up (i.e., 47,XXX karyotype). Many affected females appear to have no or very few associated symptoms, while others may have various abnormalities.

However, investigators indicate that Triplo X Syndrome is a relatively common cause of learning difficulties, particularly language-based disabilities (e.g., dyslexia), in females. Evidence suggests that affected females typically have normal intelligence with IQs that tend to be lower than that of their brothers and sisters (siblings). Mental retardation rarely occurs. Infants and children with Triplo X Syndrome may tend to have delayed acquisition of certain motor skills and delayed language and speech development.

Affected females often are of tall stature. According to researchers, although sexual development and fertility are usually normal, some may have delayed puberty and/or fertility problems. In addition, in some cases, certain physical abnormalities have been reported, such as a relatively small head, vertical skin folds that may cover the eyes' inner corners (epicanthal folds), and/or other findings. Triplo X Syndrome results from errors during the division of reproductive cells in one of the parents.


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

National Dissemination Center for Children with Disabilities
P.O. Box 1492
Washington, D.C. 20013
Tel: (202)884-8200
Fax: (202)884-8441
Tel: (800)695-0285
TDD: (800)695-0285

National Center for Learning Disabilities
381 Park Avenue South
New York, NY 10016
Tel: (212)545-7510
Fax: (212)545-9665
Tel: (888)575-7373

Learning Disabilities Association of America
4156 Library Road
Pittsburgh, PA 15234-1349
Tel: (412)341-1515
Fax: (412)344-0224
Tel: (888)300-6710

International Dyslexia Association
40 York Rd., 4th Floor
Baltimore, MD 21204
Tel: (410)296-0232
Fax: (410)321-5069
Tel: (800)222-3123

UNIQUE - Rare Chromosome Disorder Support Group
P.O. Box 2189
Surrey, Intl CR3 5GN
United Kingdom
Tel: 44 0 1883 330766
Fax: 44 0 1883 330766

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

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

Madisons Foundation
PO Box 241956
Los Angeles, CA 90024
Tel: (310)264-0826
Fax: (310)264-4766

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

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

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