Mississippi State Department of Health

Trisomy 21 (Down Syndrome)


Trisomy 21, known as Down syndrome, is a genetic disorder resulting from genetic errors on the 21st chromosome. Down syndrome causes a range of intellectual impairments and developmental delays as well as health conditions.

Down syndrome is the most common Trisomy. Although most trisomies are due to random errors, mothers over 35 years of age have an increased risk of having a child with Down syndrome. Down syndrome occurs in approximately 1 in 700 live births, or about 6,000 babies every year.

Information in Spanish Information in Vietnamese

About Down Syndrome

Impact on Development

Some children will have three copies of chromosome 21 in all of their cells (Trisomy 21) while others have three copies in only some of their cells (mosaic Down syndrome) or extra parts of chromosome 21 attached to another chromosome (Translocation Down syndrome). The severity of the impact of Trisomy 21 on development will depend upon the number of cells affected.

Children with Down syndrome have distinctive facial features such as a flattened face, a short neck, almond-shaped eyes, and a small mouth with a tongue that appears to stick out. Most will have mild to moderate developmental and intellectual disabilities, although children with Down syndrome will vary considerably in their abilities.

Trisomy 21 is also associated with other health problems. Children with Down syndrome are at an increased risk for having heart defects, digestive problems such as gastroesophageal reflux or celiac disease, and hearing and vision problems. They may also have problems with their thyroid and have increased risk for leukemia or infections.

Clinical Course and Life Expectancy

Children with Down syndrome often have low muscle tone at birth and may experience life-threatening medical conditions, such as those associated with heart defects. Unlike other Trisomy disorders, most children with Down syndrome will live into adulthood. Individuals with Down syndrome with fewer or well-managed health problems can expect to live to be 60 years of age or more.

For More Information

Treatment Options

There is no cure for Down syndrome; however, most individuals can live happy, productive lives. Medical conditions such as heart defects may require surgical correction or management with medication. Therapeutic services, such as speech, occupational, and physical therapy, should be provided as soon as possible to children with Down syndrome to assist their development. Early Intervention services received in infancy will ensure that families have the support needed to promote their child’s development and health and improve their physical and intellectual abilities.

Down Syndrome Resources

Resources for Families

Support Services

Resource Centers or Clearinghouses

National and Local Organizations

Education and Support Programs

Resources for Healthcare Providers

Prenatal Screening

General Resources

Links referenced on this page
Information in Spanish    http://msdh.ms.gov/msdhsite/index.cfm/41,14812,285,pdf/Trisomy_21_Spanish.pdf
Information in Vietnamese    http://msdh.ms.gov/msdhsite/index.cfm/41,14811,285,pdf/Trisomy_21_Vietnamese.pdf
Genetics Home Reference: Down Syndrome    https://ghr.nlm.nih.gov/condition/down-syndrome
Healthcare for Families of Children with Down Syndrome – Academy of Pediatrics (AAP)    https://www.healthychildren.org/English/health-issues/conditions/developmental-disabilities/Pages/Children-with-Down-Syndrome-Health-Care-Information-for-Families.aspx
National Library of Medicine — MedlinePlus: Trisomy 21    https://medlineplus.gov/genetics/condition/down-syndrome/Genetics
The National Down Syndrome Congress (NDSC)    https://www.ndsccenter.org
Down Syndrome Diagnosis Network    https://www.dsdiagnosisnetwork.org/
The Arc of Mississippi    https://www.arcms.org/
Mississippi Society for Disabilities    https://www.msdisabilities.com/
The Mississippi Division of Medicaid    https://medicaid.ms.gov/medicaid-coverage/how-to-apply/
Down Syndrome Resource Foundation (DSRF)    https://www.dsrf.org/information/medical-and-health-information/
National Down Syndrome Society    https://www.nads.org/
Central Mississippi Down Syndrome Society    https://www.cmdss.org/
Gulf Coast Down Syndrome Society    https://gcdss.org/
MSDH's Children and Youth with Special Health Care Needs (CYSHCN) program    http://msdh.ms.gov/msdhsite/index.cfm/41,0,163,html ok
MSDH's First Steps Early Intervention program    http://msdh.ms.gov/msdhsite/index.cfm/41,0,74,html ok
MSDH's Healthy Moms, Healthy Babies program    http://msdh.ms.gov/msdhsite/index.cfm/41,0,106,html ok
PACER    https://www.pacer.org/about/howpacerhelps.asp
American College of Medical Genetics — Trisomy 21: Positive Cell Free DNA Screen    https://www.acmg.net/PDFLibrary/Trisomy-21.pdf
Prenatal Diagnosis for Congenital Malformations and Genetic Disorders: Practice Essentials, Noninvasive Techniques, Invasive Techniques    https://emedicine.medscape.com/article/1200683-overview
Down Syndrome    https://emedicine.medscape.com/article/943216-overview
Prenatal Imaging Findings in Down Syndrome    https://emedicine.medscape.com/article/402863-overview
Postnatal Down Syndrome Imaging    https://emedicine.medscape.com/article/408344-overview
Oral Health Fact Sheet for Medical Professionals: Children with Down Syndrome (Trisomy 21)    https://dental.washington.edu/wp-content/media/sp_need_pdfs/Down-Medical.pdf
Prenatal Genetic Screening Tests    https://www.acog.org/womens-health/faqs/prenatal-genetic-screening-tests
Genetic Disorders    https://www.acog.org/womens-health/faqs/genetic-disorders
Prenatal Genetic Testing Chart    https://www.acog.org/womens-health/infographics/prenatal-genetic-testing-chart
3 Questions to Ask Yourself Before Getting Prenatal Genetic Testing    https://www.acog.org/womens-health/experts-and-stories/the-latest/3-questions-to-ask-yourself-before-getting-prenatal-genetic-testing
American Academy of Pediatrics. Bull MJ and the Committee on Genetics. Health Supervision for Children With Down Syndrome. Pediatrics 2011;128;393; DOI: 10.1542/peds.2011-1605;    https://pediatrics.aappublications.org/content/pediatrics/128/2/393.full.pdf
Glinianaia SV, Morris JK, Best KE, Santoro M, Coi A, Armaroli A, et al. (2020) Long-term survival of children born with congenital anomalies: A systematic review and meta-analysis of population-based studies. PLoS Med 17(9): e1003356.    https://journals.plos.org/plosmedicine/article?id=10.1371
Lantin-Hermoso MR, Berger S, Bhatt AB, Richerson JE, Morrow R, Freed MD, Beekman RH. The Care of Children with Congenital Heart Disease in Their Primary Medical Home. Pediatrics 2017;140(5);e20172607;    https://doi.org/10.1542/peds.2017-2607
Lee CF, Lee CH, Hsueh WY, Lin MT, Kang KT. Prevalence of obstructive sleep apnea in children with Down syndrome: a meta-analysis. J Clin Sleep Med. 2018;14(5):867–875;    https://jcsm.aasm.org/doi/pdf/10.5664/jcsm.7126
Lipkin, P.H., Okamoto, J., and the Council on Children with Disabilities and the Council on School Health. The Individuals With Disabilities Education Act (IDEA) for Children With Special Educational Needs. Pediatrics 2015;136;e1650. DOI: 10.1542/peds.2015-3409;    https://pediatrics.aappublications.org/content/pediatrics/136/6/e1650.full.pdf

Resources referenced
Information in Spanish    https://msdh.ms.gov/msdhsite/index.cfm/41,14812,285,pdf/Trisomy_21_Spanish.pdf ok
Information in Vietnamese    https://msdh.ms.gov/msdhsite/index.cfm/41,14811,285,pdf/Trisomy_21_Vietnamese.pdf ok

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