Trisomy 21

What is Trisomy 21 (Down syndrome)?

Trisomy 21, also known as Down syndrome, is a condition that causes intellectual disability and a wide range of medical problems. It occurs when there are three copies of chromosome 21 in the cells of the body instead of two. The symptoms seen in Down syndrome are a result of this extra material impacting the growth and development of an affected individual.

The symptoms of Down syndrome vary greatly. Common features include mild to moderate intellectual disability, delays in development, unique facial features, and low muscle tone. Many other medical conditions—such as heart defects, gastrointestinal issues, hearing loss, and vision problems—can also be seen. The average life span for someone with Down syndrome is now over the age of 60, although this does depend on the severity of an individual’s specific health issues.

How common is Trisomy 21 (Down syndrome)?

The incidence of Down syndrome in the population is 1 in 800 live births.

How is Trisomy 21 (Down syndrome) treated?

Treatment for Down syndrome is directed at managing the specific needs of each individual. This often means receiving care through a team of specialists that may include physicians, speech pathologists, occupational therapists, physical therapists, and social workers. Infants and children diagnosed with Down syndrome will often benefit from receiving early intervention and other supportive services beginning at a young age.

What is the prognosis for an individual with Trisomy 21 (Down syndrome)?

Outcomes for people with Down syndrome have improved significantly in the past 40 years. On average, most individuals who receive appropriate medical care will live into their sixties.

Other names for
Trisomy 21

Down syndrome

References

Akhtar et al., 2022, https://www.ncbi.nlm.nih.gov/books/NBK526016/
Baumer et al., 2014, Curr Opin Pediatr, 26(4):428-34, PMID: 25010137
Gardner, R. J. M., & Sutherland, G. R. (2011). Chromosome abnormalities and genetic counseling (4th ed.). New York: Oxford University Press, Inc.
Jones, K. L. (Ed.). (2013). Smith’s recognizable patterns of human malformation (7th ed.). Philadelphia: Elsevier Inc.
Roizen et al., 2003, Lancet, 361(9365):1281-9, PMID: 12699967
de Graaf et al., 2015, Am J Med Genet, Part A(167A):756–767, PMID: 25822844

Resources

Down Syndrome Diagnosis Network

The mission of the Down Syndrome Diagnosis Network is to “connect, support, and provide accurate information for families with a Down syndrome diagnosis.” DSDN’s vision is to “ensure families have unbiased and factually accurate diagnosis experiences, every time, through which families quickly know they're not alone.”

Address: PO Box 140, Stillwater, MN 55082

Phone:
612-460-0765

National Down Syndrome Society

NDSS is a national advocacy organization working "for the value, acceptance and inclusion of people with Down syndrome."

Address: 1155 15th Street NW Suite 540 Washington, DC 20005

Phone:
800-221-4602

National Down Syndrome Congress

Since 1973 NDSC has worked to "provide information, advocacy and support concerning all aspects of life for individuals with Down syndrome."

Address: 30 Mansell Court, Suite 108 Roswell, GA 30076

Phone:
800-232-NDSC (6372)

Lettercase

The “Understanding a Down Syndrome Diagnosis” booklet is intended for patients whose pregnancy has an increased chance for a prenatal diagnosis of Down syndrome. This book includes basic information about Down syndrome, such as potential medical conditions, reproductive options, and resources.

Address: 114 Mineral Industries Building, University of Kentucky, Lexington, KY 40506

Phone:
(770) 310-3885

DSC2U: Down Syndrome Clinic to You

DSC2U is a resource that allows "families to get up-to-date, personalized health and wellness information for their loved one with Down syndrome. DSC2U provides customized information for people with Down syndrome from age one through adulthood/senior years."