Skip to content

Children's Health

Font Size

Chromosome 9, Trisomy 9p (Multiple Variants)

It is possible that the main title of the report Chromosome 9, Trisomy 9p (Multiple Variants) 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 9P Syndrome (Partial), Included
  • Chromosome 9, Partial Trisomy 9P, Included
  • Chromosome 9, Complete Trisomy 9P
  • Rethore Syndrome (obsolete)
  • Duplication 9p Syndrome
  • Dup(9p) Syndrome
  • Chromosome 9, Trisomy 9pter-q11-13, Included
  • Chromosome 9, Trisomy 9pter-q22-32, Included

Disorder Subdivisions

  • None

General Discussion

This disease entry was made possible due to the generosity of the Robert Lee and Clara Guthrie Patterson Trust, through grant funds provided for the National Organization for Rare Disorders' "Pediatric Rare Disease Database Project."

Chromosome 9, Trisomy 9p is a rare chromosomal syndrome in which a portion of the 9th chromosome appears three times (trisomy) rather than twice in cells of the body. The trisomy may involve a portion of the short arm (9p), the entire short arm, or the short arm and a portion of the long arm (9q) of chromosome 9. (Each chromosome contains a short arm known as "p" and a long arm designated as "q.") Evidence suggests that, in many cases, associated symptoms and findings may be relatively similar among affected infants despite differing lengths of the trisomic (duplicated) segment of 9p. However, in those with larger trisomies (e.g., extending to middle or end [distal] regions of 9q), additional features may also be present that appear to correlate with the extent of the duplication.

Virtually all individuals with Trisomy 9p are affected by mental retardation and distinctive malformations of the skull and facial (craniofacial) region. In some instances, additional physical abnormalities may also be present, such as other skeletal defects, structural malformations of the heart that are present at birth (congenital heart defects), and/or other findings. In some cases, the trisomy appears to result from a balanced chromosomal rearrangement in one of the parents; in others, it is thought to arise from spontaneous (de novo) errors very early in embryonic development that occur for unknown reasons (sporadically).


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

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

The Arc
1825 K Street NW, Suite 1200
Washington, DC 20006
Tel: (202)534-3700
Fax: (202)534-3731
Tel: (800)433-5255
TDD: (817)277-0553

P.O. Box 751112
Limekiln, PA 19535
Tel: (702)769-9264
Fax: (702)341-5351
Tel: (888)486-1209

Trisomy 9 International Parent Support (9TIPS)
4027 E. Piedmont Drive
Highland, CA 92346
Tel: (909)862-4470

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

Support Organization for Trisomy 13/18 and Related Disorders, UK
c/o Christine Rose
48 Froggatts Ride
Sutton Coldfield
West Midlands, B76 2TQ SOFT
United Kingdom
Tel: 01213513122

UNIQUE - Rare Chromosome Disorder Support Group
P.O. Box 2189
Surrey, CR3 5GN
United Kingdom
Tel: 4401883330766
Fax: 4401883330766

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

Support Organisation for Trisomy and Related Disorders

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

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: 4/7/2008
Copyright 1996, 1997, 2001 National Organization for Rare Disorders, Inc.

WebMD Medical Reference from the National Organization for Rare Disorders

Last Updated: May 28, 2015
This information is not intended to replace the advice of a doctor. Healthwise disclaims any liability for the decisions you make based on this information.

Today on WebMD

child with red rash on cheeks
What’s that rash?
plate of fruit and veggies
How healthy is your child’s diet?
smiling baby
Treating diarrhea, fever and more.
Middle school band practice
Understanding your child’s changing body.

worried kid
jennifer aniston
Measles virus
sick child

Child with adhd
rl with friends
Syringes and graph illustration