Down Syndrome

National Organization for Rare Disorders, Inc.

Important
It is possible that the main title of the report Down 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.

Synonyms

  • Chromosome 21, Mosaic 21 Syndrome
  • Chromosome 21, Translocation 21 Syndrome
  • Trisomy 21 Syndrome
  • Trisomy G Syndrome

Disorder Subdivisions

  • None

General Discussion

Down syndrome is a chromosomal condition in which all or a portion of chromosome 21 appears three times (trisomy) rather than twice in cells of the body. In some affected individuals, only a percentage of cells may contain the chromosomal condition (mosaicism).

Symptoms and findings may vary greatly in range and degree, depending on the specific length and location of the duplicated (trisomic) portion of chromosome 21 as well as the percentage of cells containing the condition. However, in many affected individuals, such characteristics may include low muscle tone (hypotonia); a tendency to keep the mouth open with protrusion of the tongue; and distinctive facial characteristics including a short, small head (microbrachycephaly), upwardly slanting eyelid folds (palpebral fissures), a depressed nasal bridge, a small nose, and a relatively flat facial profile. Individuals with Down syndrome may also have unusually small, misshapen (dysplastic) ears; a narrow roof of the mouth (palate); vertical skin folds covering the inner corners of the eyes (epicanthal folds); dental abnormalities; and excessive skin on the back of the neck. Other characteristics include unusually short arms and legs; short fingers; and unusual skin ridge patterns (dermatoglyphics) on the fingers, palms, and toes. Individuals with Down syndrome may also have short stature, poor coordination, mild to severe intellectual disability, and hearing impairment.

In some cases, Down syndrome may also be characterized by structural malformations of the heart at birth (congenital heart defects). In addition, those with the condition may have an increased susceptibility to respiratory disease (e.g., pneumonia), other infectious diseases, and malignancies in which there is an increased proliferation of certain white blood cells (leukemia). Rarely do these conditions lead to potentially life-threatening complications.

Resources

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

Arc (a national organization on mental retardation)
1010 Wayne Ave
Suite 650
Silver Spring, MD 20910
Tel: (301)565-3842
Fax: (301)565-3843
Tel: (800)433-5255
TDD: (817)277-0553
Email: info@thearc.org
Internet: http://www.thearc.org/

National Down Syndrome Congress
1370 Center Drive
Suite 102
Atlanta, GA 30338
USA
Tel: (770)604-9500
Fax: (770)604-9898
Tel: (800)232-6372
Email: info@ndsccenter.org
Internet: http://www.ndsccenter.org

National Down Syndrome Society
666 Broadway
8th Floor
New York, NY 10012-2317
USA
Tel: (212)460-9330
Fax: (212)979-2873
Tel: (800)221-4602
Email: info@ndss.org
Internet: http://www.ndss.org/

PHP - Parents Helping Parents, Inc.
Sobrato Center For Nonprofits-San Jose
1400 Parkmoor Avenue
Suite 100
Sant Jose, CA 95126
USA
Tel: (408)727-5775
Fax: (408)286-1116
Tel: (866)747-4040
TDD: (408)727-5775
Email: info@php.com
Internet: http://www.php.com

Association for Children with Down Syndrome, Inc.
4 Fern Place
Plainview, NY 11803
Tel: (516)933-4700
Fax: (516)933-9524
Email: msmith@acds.org
Internet: http://www.acds.org

National Center for Down's Syndrome
9 Westbourne Road
EDG Baston
Birmingham, B-15
United Kingdom
Tel: 0214543126

National Institute of Mental Retardation
York University
Kinsmen NIMR Building
4700 Keele Street
North York, Toronto
Ontario, M3J 1P3
Canada
Tel: 4166619611

NIH/National Institute of Child Health and Human Development
31 Center Dr
Building 31, Room 2A32
MSC2425
Bethesda, MD 20892
Tel: (301)496-5133
Fax: (301)496-7101
Internet: http://www.nichd.nih.gov/

Birth Defect Research for Children, Inc.
800 Celebration Ave, Suite 225
Orlando, FL 34747
USA
Tel: (407)566-8304
Fax: (407)895-0824
Email: staff@birthdefects.org
Internet: http://www.birthdefects.org

International Mosaic Down Syndrome Association
PO Box 1052
Franklin, TX 77856
Tel: (979)828-4177
Fax: (775)295-9373
Tel: (888)637-5465
Email: president@imdsa.org
Internet: http://www.imdsa.org/

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

R.O.C.K. (Raising Our Celiac Kids)
3527 Fortuna Ranch Rd
Encinitas, CA 92024
USA
Tel: (858)395-5421
Fax: (858)756-0431
Email: info@celiackids.com
Internet: http://www.celiackids.com

New Horizons Un-Limited, Inc.
811 East Wisconsin Ave
Suite 937
Milwaukee, WI 53202
USA
Tel: (414)299-0124
Fax: (414)347-1977
Email: horizons@new-horizons.org
Internet: http://www.new-horizons.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

ANDO (Apoyo al Nino Down)
Dept. of Medical Genetics, Children's Hospital
111 Michigan Ave
Washington, DC 20010
Tel: (202)884-2187
Fax: (202)884-2390
Email: curuburo@cnmc.org

National Foundation for Celiac Awareness
P.O. Box 544
Ambler, PA 19002
Tel: (215)325-1306
Fax: (215)643-1707
Email: info@CeliacCentral.org
Internet: http://www.CeliacCentral.org

Perkins School for the Blind
175 North Beacon St.
Watertown, MA 02472
Tel: (617)924-3434
Fax: (617)926-2027
Email: Info@Perkins.org
Internet: http://www.Perkins.org

National Consortium on Deaf-Blindness (NCDB)
The Teaching Research Institute
Western Oregon University
345 N. Monmouth Ave.
Monmouth, OR 97361
Tel: (800)438-9376
Fax: (503)838-8150
Tel: (800)438-9376
TDD: (800)854-7013
Email: info@nationaldb.org
Internet: http://www.nationaldb.org

PLAN Institute for Caring Citizenship
260-3665 Kingsway
Vancouver
British Columbia, V5R 5W2
Canada
Tel: 604-439-9566
Fax: 604-439-7001
Email: inquiries@planinstitute.ca
Internet: http://www.planinstitute.ca/?q=learnfromus/library

Child Neurology Foundation
2000 West 98th Street
Bloomington, MN 55431
USA
Tel: (952)641-6100
Fax: (952)881-6276
Tel: (800)263-5430
Email: jstone@childneurologyfoundation.org
Internet: http://www.childneurologyfoundation.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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