Also called: Trisomy 21
Important: This page is general information, not medical advice. It does not recommend or prescribe any treatment. Always consult your doctor or pharmacist before starting, stopping or changing any medicine.
About Down Syndrome
Down syndrome is a condition in which a person has an extra chromosome or an extra piece of a chromosome. This extra copy changes how a baby's body and brain develop. It can cause both mental and physical challenges during their lifetime. Even though people with Down syndrome might act and look similar, each person has different abilities.
Chromosomes are tiny "packages" in your cells that contain your genes. Genes carry information, called DNA, that controls what you look like and how your body works. People with Down syndrome have an extra copy of chromosome 21. In some cases, they may have an extra copy of part of the chromosome. Having an extra copy of a chromosome is called trisomy. So sometimes Down syndrome is also called trisomy 21.
Down syndrome is usually not inherited. It happens by chance, as an error when cells are dividing during early development of the fetus. It is not known for sure why Down syndrome occurs or how many different factors play a role.
One factor that increases the risk of having a baby with Down syndrome is the age of the mother. Women ages 35 and older are more likely to have a baby with Down syndrome.
The symptoms of Down syndrome are different in each person. And people with Down syndrome may have different problems at different times of their lives. They usually have mild to moderate intellectual disabilities. Their development is often delayed. For example, they may start talking later than other children.
Some of the common physical signs of Down syndrome include:
- A flat face
- Eyes that slant up
- A short neck
- Small hands and feet
- Poor muscle tone
- Loose joints
Many people with Down syndrome have the common physical signs and have healthy lives. But some people with Down syndrome might have one or more birth defects or other health problems. Some of the more common ones include:
- Hearing loss
- Sleep apnea (a disorder that causes you to repeatedly stop breathing during sleep)
- Ear infections
- Eye diseases
- Congenital heart defects (heart defects that are present at birth)
- Digestive problems
- Problems with the upper part of the spine
- Obesity
Health care providers can check for Down syndrome during pregnancy or after a child is born.
There are two basic types of tests that help find Down syndrome during pregnancy:
- Prenatal screening tests can show whether your unborn baby has a higher or lower chance of having Down syndrome. If a screening test shows that your baby could have Down syndrome, you'll need another test to find out for sure.
- Prenatal diagnostic tests can diagnose or rule out Down syndrome by checking the chromosomes in a sample of cells. These tests have a small risk of causing a miscarriage, so they're often done after a screening test shows that an unborn baby could have Down syndrome.
After a baby is born, the provider may make an initial diagnosis of Down syndrome based on the physical signs of the syndrome. The provider can use a karyotype genetic test to confirm the diagnosis. The test can check for extra chromosomes in a sample of the baby's blood.
There is no single, standard treatment for Down syndrome. Treatments are based on each person's physical and intellectual needs, strengths, and limitations.
Services early in life focus on helping children with Down syndrome develop to their full potential. These services include speech, occupational, and physical therapies. They are typically offered through early intervention programs in each state. Children with Down syndrome may also need extra help or attention in school, although many children are included in regular classes.
Since people with Down syndrome can have birth defects and other health problems, they will need regular medical care. They may need to have certain extra health screenings to check for problems that happen more often in people with Down syndrome.
Centers for Disease Control and Prevention
It sits within Genetics/Birth Defects.
The lead U.S. institute for this subject is the Eunice Kennedy Shriver National Institute of Child Health and Human Development.
When to speak to someone. Reading about a topic cannot tell you whether it applies to you. Speak to a doctor or pharmacist if symptoms are severe, sudden, getting worse, or simply not going away — and seek emergency care immediately for chest pain, breathing difficulty, sudden weakness or confusion, or a serious allergic reaction.
Research on Down Syndrome
477 studies areregistered for this condition on ClinicalTrials.gov, the U.S. National Library of Medicine's public registry. A selection is below — the links go straight to the registry entry, not to a summary of ours.
What a registered study does and does not mean. Registration means a study exists and has been declared publicly. It says nothing about whether the treatment being tested works, is safe, or is available to you. Many studies find no benefit — that is what research is for. Never seek out an experimental treatment on the strength of a registry entry alone.
Research currently under way
- A Study to Investigate Blinatumomab in Combination With Chemotherapy in Patients With Newly Diagnosed B-Lymphoblastic LeukemiaNational Cancer Institute (NCI)
- Non-Invasive Brain Stimulation to Improve Language in Down Syndrome.Floriana Costanzo
- Harness-based Mobility Intervention for Infants With Down SyndromeBoston University Charles River Campus
- Co-Designing and Evaluating Additional Mothers and Babies Program Content for Expectant and New Parents of Children With Down SyndromeNorthwestern University
- NAD Augmentation to Prevent or Reverse Alzheimer's Disease in People With Down SyndromeBrigham and Women's Hospital
- Metric-Optimized Spectacle Prescriptions for Children With Down SyndromeOhio State University
Research already completed
- MOTOR PROFICIENCY AND HEALTH-RELATED FITNESS IN DOWN SYNDROMECairo University
- Therapies for Down Syndrome Regression DisorderUniversity of Colorado, Denver
- The (Cost)Effectiveness of a Social Robot for Persons With Problems in Daily Structure and Planning in Disability CareAcademy Het Dorp
- Positive Airway Pressure (PAP) for Children With Down Syndrome (DS) and Obstructive Sleep Apnea Syndrome (OSAS)University of Miami
- Leucettinib-21 First-in-Human Phase 1 in Healthy Volunteers and Subjects With Down Syndrome and Alzheimer's DiseasePerha Pharmaceuticals
Study data from ClinicalTrials.gov, a service of the U.S. National Library of Medicine. Retrieved 2026-07-30. Registry entries are supplied by study sponsors and investigators; ClinicalTrials.gov does not verify their scientific validity. PocketsInfo is not affiliated with, and not endorsed by, the NLM or the NIH.
Where to read more
Rather than paraphrase, we point you to the primary sources. Every link below is to a government health agency, a national institute or a recognised medical body — grouped by what you are trying to find out.
Start Here
- About Down SyndromeEunice Kennedy Shriver National Institute of Child Health and Human Development
- About Down SyndromeNational Down Syndrome Society
- Down SyndromeCenters for Disease Control and Prevention
- Down Syndrome (For Parents)Nemours Foundation
Diagnosis and Tests
- Alpha-Fetoprotein (AFP) TestNational Library of Medicine
- Down Syndrome TestsNational Library of Medicine
- How Do Health Care Providers Diagnose Down Syndrome?Eunice Kennedy Shriver National Institute of Child Health and Human Development
Treatments and Therapies
- What Are Common Treatments for Down Syndrome?Eunice Kennedy Shriver National Institute of Child Health and Human Development
Related Issues
- ADHD and Down SyndromeNational Down Syndrome Society
- Alzheimer's Disease in People with Down SyndromeNational Institute on Aging
- Blood Diseases and Down SyndromeNational Down Syndrome Society
- Dentistry and Down SyndromeNational Down Syndrome Society
- Down Syndrome: Eye ProblemsAmerican Association for Pediatric Ophthalmology and Strabismus
- Dual Diagnosis of Down Syndrome and AutismNational Down Syndrome Society
- Ear, Nose, and Throat (ENT) and Down SyndromeNational Down Syndrome Society
- Gastrointestinal System and Down SyndromeNational Down Syndrome Society
- Mental Health and Down SyndromeNational Down Syndrome Society
- Sleep and Down SyndromeNational Down Syndrome Society
- Surgery and Down SyndromeNational Down Syndrome Society
Genetics
- About Down SyndromeNational Human Genome Research Institute
- Down syndrome: MedlinePlus GeneticsNational Library of Medicine
Statistics and Research
- DS-Connect: The Down Syndrome RegistryEunice Kennedy Shriver National Institute of Child Health and Human Development
- Welcome to the Down Syndrome ConsortiumEunice Kennedy Shriver National Institute of Child Health and Human Development
Clinical Trials
- ClinicalTrials.gov: Down SyndromeNational Institutes of Health
Medical subject headings
Clinicians and researchers index this subject under Down Syndrome. These are the terms to use when searching medical literature.
This page is built from the MedlinePlus health topic record for Down Syndrome, a service of the U.S. National Library of Medicine (NLM), National Institutes of Health. Information is from MedlinePlus.gov. PocketsInfo is not affiliated with, and is not endorsed by, the NLM or the NIH. Retrieved 30 July 2026.