While Down syndrome can change the course of a baby’s — and a family’s — life, people with the condition are living longer and more fulfilling lives than ever before. Here’s what parents and parents-to-be should know about Down syndrome.
What is Down syndrome?
Down syndrome is a chromosomal disorder that causes a set of mental and physical symptoms that range from mild to severe. Down syndrome is also called trisomy 21 because people with Down syndrome have three number-21 chromosomes instead of two.
An estimated 6,000 U.S. babies — or about one in 700 — are born with Down syndrome each year, according to the Centers for Disease Control and Prevention (CDC).
The medical needs of children with Down syndrome can vary. Some children with more severe symptoms may require more care and treatment than others. However, most people with Down syndrome are able to live full, healthy lives.
Types of Down syndrome
Down syndrome occurs when fetal cells grow and divide differently than what is typical. This can happen in a few different ways, leading to different types of Down syndrome.
- Trisomy 21 or nondisjunction is the most common type of Down syndrome, accounting for 95 percent of all cases. It happens when an embryo develops three copies of chromosome 21 instead of two.
- Translocation occurs in about 3 percent of Down syndrome cases. This happens when a full or partial copy of chromosome 21 attaches to another chromosome.
- Mosaicism occurs in about 2 percent of Down syndrome cases. It happens when some cells have the usual 46 chromosomes while others have 47, causing some cells with 47 chromosomes to have an extra copy of chromosome 21.
What causes Down syndrome?
Down syndrome is caused by a cell division that happens as an embryo is forming. When a baby is conceived, it typically receives 23 chromosomes from its mother and 23 from its father for a total of 46 chromosomes. In the case of Down syndrome, a developing embryo gets an additional copy of one chromosome — chromosome 21.
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Experts don’t fully understand why this happens, but maternal age may play a role. Women over 35 are more likely to have a child with Down syndrome compared to women who are younger, and the chances increase even more significantly for women over age 40.
That said, there’s nothing a mother (or father) can do to “cause” a child to have Down syndrome. And there’s no way to prevent it.
What are the signs of Down syndrome in infants?
A baby with Down syndrome may have physical characteristics like:
- A smaller-than-average head
- A broad, flat face with upward slanting eyes and a short nose
- A larger-than-average tongue
- Extra skin around the back of the neck
- Small, rounded, low-set ears
Infants with Down syndrome may:
- Appear flaccid or floppy, due to low muscle tone
- Act unusually passive and cry infrequently
- Have sucking or feeding problems
- Have constipation or digestive issues, or a congenital condition called duodenal atresia
- Reach developmental milestones like sitting up, crawling or walking later than other babies
- Are more likely to have certain types of heart defects
Screening for Down syndrome during pregnancy
Screening and diagnostic tests can detect Down syndrome early in pregnancy, usually by 20 weeks (and sometimes before week 12).
Screening tests, which are noninvasive and low-risk, can estimate the risk that a fetus has Down syndrome. The tests look at a sample of your blood, which contains DNA from your baby’s placenta.
While screening tests were once reserved for women over 35 or with other risk factors, the American College of Gynecologists and Obstetricians (ACOG) now recommend all women discuss prenatal screening options with their doctor.
Commonly used noninvasive prenatal screenings tests (or NIPTs) include nuchal translucency testing, cell-free DNA testing, triple or quadruple screens and integrated screens. NIPT results can help you and your doctor determine whether more invasive diagnostic tests are needed.
Diagnostic tests can tell whether a fetus has Down syndrome or another chromosomal disorder. These tests, which are more invasive and involve collecting genetic material from a baby’s placenta or amniotic fluid, include chorionic villus sampling (CVS), amniocentesis and Cordocentesis, also know as percutaneous umbilical sampling. There are advantages and disadvantages to each type of diagnostic test, so it’s important to weigh the benefits and risks with your doctor before deciding which one is best for you.
If Down syndrome is suspected based on the results of prenatal diagnostic testing, the results can be confirmed with a blood test after a baby is born. However, having a diagnosis during pregnancy can help parents-to-be prepare and line up medical care that can begin immediately after birth.
Latest treatments for Down syndrome
There’s no cure for Down syndrome. But thanks to improvements in medical care and therapies, people with Down syndrome have richer lives than they did a generation ago.
Children with Down syndrome reach developmental milestones — they just may take longer to get there. As adults, they can work and may even live on their own or in group homes.
Children with Down syndrome often have a team of specialists to address the physical and mental challenges surrounding the disorder. That team might include pediatric experts such as cardiologists, neurologists, speech therapists, audiologists, occupational and physical therapists, endocrinologists, ophthalmologists, ear, nose and throat specialists, and social workers. An individual child’s treatment will depend on her unique physical and intellectual needs.
In most cases, surgery can correct serious issues such as heart or gastrointestinal defects, and early intervention therapies — which can begin shortly after birth — can give children with Down syndrome the best chance of reaching their potential. Early intervention services can continue until a child turns 3; after that, children are eligible to continue getting the treatment they need through their local school district.
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