What is Down syndrome?
Down syndrome is a genetic condition caused by an extra copy of chromosome 21. This extra chromosome can create physical and developmental differences as a person grows. Every person experiences Down syndrome differently and its effects are lifelong. Down syndrome is often associated with other health conditions, such as heart, breathing and sleep issues.
How common is Down syndrome?
Down syndrome is the most common neurodevelopmental disorder based on a genetic cause. It occurs in 1 out of every 750 to 1,100 live births.
What causes Down syndrome?
Down syndrome is a genetic disorder.
Most people have 46 total chromosomes (23 pairs) in every cell in their body. One chromosome of each pair comes from the father, and one chromosome of each pair comes from the mother.
In Down syndrome, uneven cell division leads to an extra full or partial copy of chromosome 21. This extra chromosome copy causes differences in how the brain and body systems develop.
Who gets Down syndrome?
Down syndrome can occur in anyone. The risk of Down syndrome increases with the age of the pregnant parent, especially after age 35.
What are the types of Down syndrome?
There are three genetic types of Down syndrome. Each type impacts the body's chromosomes, which tell our body how to grow.
- Trisomy 21, or nondisjunction, accounts for 95% of Down syndrome cases. It happens when an extra copy of chromosome 21 is present in all the body’s cells.
- Translocation Down syndrome occurs in about 4% of babies with Down Syndrome. In translocation Down syndrome, a part of the 21st chromosome becomes attached to another chromosome, resulting in an extra copy of genetic material. It is the only type of Down syndrome that can be inherited (passed down) from a parent.
- Mosaic Down syndrome occurs in 1% of babies with Down syndrome. It happens when an extra copy of chromosome 21 is present in some, but not all, of the body’s cells. This type of Down syndrome results from a random event shortly after the egg and sperm join. When cells are dividing, some cells receive an extra copy of chromosome 21.
What to expect about health and development
Children with Down syndrome experience cognitive delays. However, the effect varies greatly by individual and does not take away from the many strengths and talents of each child.
Children with Down syndrome are also at increased risk of certain medical conditions such as congenital heart defects, respiratory and sleep difficulties, vision and hearing problems, constipation and thyroid conditions.
New treatment advancements, along with strong educational programs, a stimulating home environment, quality healthcare and positive support help people with Down syndrome lead fulfilling and meaningful lives.
What are the signs of Down syndrome?
Every child with Down syndrome is a unique individual. There are some physical characteristics that children with Down syndrome may have in common, including:
- Low muscle tone
- Small stature
- An upward slant to the eyes
- A single horizontal crease across the center of the palm instead of multiple creases
Children with Down syndrome may possess these characteristics to different degrees, or not at all.
Signs and symptoms of Down syndrome during pregnancy
The pregnant parent won’t feel or notice symptoms that could indicate their baby has Down syndrome. Imaging experts may look for certain signs of Down syndrome, such as extra fluid on the back of the neck, during an ultrasound.
What tests are used to diagnose Down syndrome?
Doctors can diagnose Down syndrome before or after birth. A prenatal (before birth) genetic counselor or geneticist can give you the most accurate information about the likelihood of having a baby with Down syndrome.
Screening before birth
- Prenatal tests can screen for the potential of Down syndrome during the first and second trimester. This includes cell-free DNA tests and certain blood or serum tests.
Diagnostic testing before birth
- Our doctors can only confirm a diagnosis of Down syndrome prenatally through a test called amniocentesis or chorionic villus sampling.
Testing after birth
- If parents don’t have prenatal testing, providers most often notice Down syndrome at birth or shortly thereafter.
- Physical characteristics alone are not enough for a diagnosis.
- At Children’s Colorado, we use high-resolution chromosome testing to diagnose Down syndrome after birth. This test will show the number of total chromosomes and can detect an extra copy of the 21st chromosome to determine if translocation Down Syndrome is present.
What should I do after a Down syndrome diagnosis?
In addition to providing a wide range of services for children and adolescents with Down syndrome, the Sie Center for Down Syndrome offers prenatal consultations for families who have received a prenatal diagnosis of Down syndrome. During this prenatal visit, our physician and social worker can:
- Answer questions about Down syndrome
- Provide accurate information about medical and developmental outcomes
- Provide resources such as support groups, early intervention and education
- Explain the services available at the Sie Center, including long-term support
This consultation should not replace recommendations from your obstetrician or perinatologist. Please continue to follow any recommendations they have given you.
How is Down syndrome treated?
The Sie Center for Down Syndrome at Children’s Colorado has a team of experts including doctors, therapists, mental and behavioral health providers, social workers, education specialists and more.
Treatment for Down syndrome looks different for every child, but here are some things you might expect:
- Children with Down syndrome need labs and other screenings to look for changes in thyroid and iron levels, and to detect celiac disease.
- Developmental therapies and specialized education plans may help children with Down syndrome learn and grow.
- Some children with Down syndrome need medications for issues like thyroid disease, sleep apnea, seizures and constipation.
- Some medical problems, like congenital heart defects, require surgery.
Why choose us for Down syndrome treatment?
The Sie Center for Down Syndrome is one of the most comprehensive programs for children with Down syndrome across the globe.
We partner with two leading programs to improve the lives of children with Down syndrome through world-class medical care and research.
Our partnership with these organizations allows us to bring the most advanced Down syndrome care to our patients sooner. We follow guidelines created by the American Academy of Pediatrics to deliver a personalized, team-based approach that meets the unique medical and developmental needs of every child.
Helpful resources
Visit our Down syndrome resources page for a full list of community programs, support groups and educational organizations for parents, families and patients.
For our detailed answers to frequently asked questions about Down syndrome in Children, visit our FAQ page.
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