Chromosome 9, Trisomy Mosaic

National Organization for Rare Disorders, Inc.

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It is possible that the main title of the report Chromosome 9, Trisomy Mosaic 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.


  • Trisomy 9 (Complete Trisomy 9 Syndrome), Included
  • Trisomy 9 Mosaic
  • Trisomy 9 Mosaicism
  • Trisomy 9 Mosaicism Syndrome

Disorder Subdivisions

  • None

General Discussion

Chromosome 9, Trisomy Mosaic, also known as Trisomy 9 Mosaicism syndrome, is a rare chromosomal disorder in which the entire 9th chromosome appears three times (trisomy) rather than twice in some cells of the body. The term "mosaic" indicates that some cells contain the extra chromosome 9, while others have the normal chromosomal pair.

Associated symptoms and findings may vary greatly in range and severity, depending on the percentage of cells with the extra chromosome. However, common features include growth deficiency before birth (intrauterine growth retardation); mental retardation; structural malformations of the heart that are present at birth (congenital heart defects); and/or distinctive abnormalities of the skull and facial (craniofacial) region, such as a sloping forehead, a bulbous nose, short eyelid folds (palpebral fissures), deeply set eyes, and/or low-set, malformed ears. The syndrome may also be characterized by musculoskeletal, genital, kidney (renal), and/or additional physical abnormalities. Chromosome 9, Trisomy Mosaic may be caused by errors during the division of a parent's reproductive cells (meiosis) or during the division of body tissue cells (somatic cells) early in the development of the embryo (mitosis).

Supporting Organizations


PO Box 751112
Las Vegas, NV 89136
Tel: (702)769-9264
Fax: (702)341-5351
Tel: (888)486-1209

American Heart Association

7272 Greenville Avenue
Dallas, TX 75231
Tel: (214)784-7212
Fax: (214)784-1307
Tel: (800)242-8721

Craniofacial Foundation of America

975 East Third Street
Chattanooga, TN 37403
Tel: (423)778-9176
Fax: (423)778-8172
Tel: (800)418-3223

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

March of Dimes Birth Defects Foundation

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

Support Organisation for Trisomy and Related Disorders


Support Organization for Trisomy 13/18 and Related Disorders, UK

c/o Christine Rose
48 Froggatts Ride
West Midlands, B76 2TQ SOFT
United Kingdom
Tel: 1213513122

Support Organization for Trisomy 18, 13, and Related Disorders

2982 S. Union Street
Rochester, NY 14624-1926
Fax: (585)594-1957
Tel: (800)716-7638

The Arc

1825 K Street NW, Suite 1200
Washington, DC 20006
Tel: (202)534-3700
Fax: (202)534-3731
Tel: (800)433-5255

Trisomy 9 International Parent Support (9TIPS)

4027 E. Piedmont Drive
Highland, CA 92346
Tel: (909)862-4470

UNIQUE - Rare Chromosome Disorder Support Group

The Rare Chromosome Disorder Support Group
Surrey, RH8 9EE
United Kingdom
Tel: 441883723356
Email: or

For a Complete Report

This is an abstract of a report from the National Organization for Rare Disorders (NORD). A copy of the complete report can be downloaded free from the NORD website for registered users. The complete report contains additional information including symptoms, causes, affected population, related disorders, standard and investigational therapies (if available), and references from medical literature. For a full-text version of this topic, 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. NORD recommends that affected individuals seek the advice or counsel of their own personal physicians.

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.

For additional information and assistance about rare disorders, please contact the National Organization for Rare Disorders at P.O. Box 1968, Danbury, CT 06813-1968; phone (203) 744-0100; web site or email

Last Updated:  1/15/1970
Copyright  2003 National Organization for Rare Disorders, Inc.