Trisomy X

National Organization for Rare Disorders, Inc.

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It is possible that the main title of the report Trisomy X is not the name you expected.

Disorder Subdivisions

  • None

General Discussion

Trisomy X is a disorder that affects females and is characterized by the presence of an additional X chromosome. Normally, females have two X chromosomes; however, females with trisomy X carry three X chromosomes in the nuclei of body cells. There are specific physical features (phenotype) associated with this chromosomal disorder. Common symptoms that can potentially occur include language-based learning disabilities, developmental dyspraxia, tall stature, low muscle tone (hypotonia), and abnormal bending or curving of the pinkies toward the ring fingers (clinodactyly). Trisomy X occurs randomly as a result from errors during the division of reproductive cells in one of the parents. This disorder occurs in one in 900 to 1,000 live births.

Supporting Organizations

Chromosome Disorder Outreach, Inc.

P.O. Box 724
Boca Raton, FL 33429-0724
Tel: (561)395-4252
Fax: (561)395-4252

Focus Foundation, Inc.

PO Box 190
Davidsonville, MD 21035
Tel: (443)223-7323
Fax: (410)798-4801

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

International Dyslexia Association

40 York Rd
4 Florr
Baltimore, MD 21204
Tel: (410)296-0232
Fax: (410)321-5069
Tel: (800)222-3123

Klinefelter Syndrome & Associates

P.O. Box 872
Pine, CO 80470-0872
Tel: (303)400-9040
Fax: (303)838-0753
Tel: (888)999-9428

Learning Disabilities Association of America

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

March of Dimes

1275 Mamaroneck Avenue
White Plains, NY 10605
Tel: (914)997-4488
Fax: (914)997-4763
Email: or
Website: and

National Center for Learning Disabilities

381 Park Avenue South
1420 Suite
New York, NY 10016
Tel: (212)545-7510
Fax: (212)545-9665
Tel: (888)575-7373

UNIQUE - Rare Chromosome Disorder Support Group

G1 The Stables
Station Road West
Oxted, RH8 9EE
United Kingdom
Tel: 0044 (0)1883 723356

For a Complete Report

This is an abstract of a report from the National Organization for Rare Disorders (NORD). For a full-text version of this report, go to and click on Rare Disease Database under "Rare Disease Information".

The information provided in this report is not intended for diagnostic purposes. It is provided for informational purposes only.

It is possible that the title of this topic is not the name you selected. Please check the Synonyms listing to find the alternate name(s) and Disorder Subdivision(s) covered by this report.

This disease entry is based upon medical information available through the date at the end of the topic. Since NORD's resources are limited, it is not possible to keep every entry in the Rare Disease Database completely current and accurate. Please check with the agencies listed in the Resources section for the most current information about this disorder.

Last Updated:  4/1/2014
Copyright  2014 National Organization for Rare Disorders, Inc.