Down syndrome is the most common form of intellectual disability in the world. It occurs in about 1 out every 1,000 babies born alive, and it is caused by a genetic abnormality that affects something called a chromosome.
Chromosomes are large structures found in cells that house thousands of genes. People without genetic abnormalities have 23 pairs of chromosomes, and each pair is given a number between 1 and 23.
People with Down syndrome are born with three — rather than two — copies of chromosome 21. Scientists do not know why some babies wind up with the extra chromosome, but they do know that the age of the mother plays a role. As a woman gets older, her risk of having a baby with Down syndrome steadily increases. The father's age may also be relevant, but scientists do not yet know that definitively.
This article will discuss what to expect if your baby has been diagnosed with Down syndrome. For information about how Down syndrome is diagnosed during pregnancy, (see "Patient information: Should I have a screening test for Down syndrome during pregnancy? (Beyond the Basics)").
DIFFERENCES IN APPEARANCE
If your baby has Down syndrome, you may not be able to tell immediately after birth that anything is different about him or her. Even so, most babies with Down syndrome have at least some physical characteristics that distinguish them from babies with a normal chromosomal complement:
- Newborns — Most newborns with Down syndrome will have at least a few of the following features:
- A flattened face (picture 1)
- Extra skin at back of the neck
- Eyes that slant upwards
- A lack of muscle tone (hypotonia)
- Abnormally flexible joints
- Unusual looking ears
- A crease across the palm, called a transverse palmar crease (picture 2)
- A wide gap between the first and second toes (sandal gap deformity)
- Children and adults — As they grow into adulthood, children with Down syndrome also develop many of the following characteristics (if they don't already have them) (figure 1):
- A flattened head in back (brachycephaly)
- Skin folds on the eyelids
- A flattened nose bridge
- Folded, unusual, or small ears
- A gaping mouth
- A protruding tongue
- Abnormal teeth
- A short neck
- Short, broad hands
DOWN SYNDROME COMPLICATIONS
Aside from its effects on appearance, Down syndrome can cause a number of medical complications. Some of these complications are more serious than others, but most of them can be treated. To make sure that your child's complications are appropriately managed as they emerge, have him or her screened at regular intervals (table 1).
Potentially serious complications — The most serious complications of Down syndrome include heart defects, blood disorders that can include leukemia (cancer of the blood), and immune system problems.
Heart defects — About half of all babies with Down syndrome are born with (often repairable) heart defects. Usually these defects affect the walls separating the four chambers of the heart.
Blood disorders — Down syndrome can cause blood cell abnormalities, including a form of blood cancer called leukemia.
Immune system problems — The immune system of people with Down syndrome may not work as it should. As a result, people with Down syndrome are more vulnerable than others to infections, certain kinds of cancer, and autoimmune conditions.
Stomach and digestive system — About 5 percent of babies with Down syndrome have abnormally formed digestive organs, which can block the GI tract and may require surgery. They are also more prone to celiac disease, a condition that impairs their ability to absorb nutrients and that makes them unable to tolerate a protein in wheat called gluten. (See "Patient information: Celiac disease in children (Beyond the Basics)".)
Hormonal disorders — Down syndrome can affect the way the body produces or responds to hormones. For example, people with Down syndrome often do not make sufficient thyroid hormone, which can contribute to problems with weight. They are also at risk for type 1 diabetes, which requires treatment with insulin injections.
Skeletal problems — People with Down syndrome often have too much flexibility between the bones at the top of the spine that support the head (called atlantoaxial instability). Often this condition causes no symptoms, but it can compress the spine, cause pain, or cause the head to tilt to one side. In extreme cases, this joint instability can cause paralysis.
Children who participate in sports or other activities, such as the Special Olympics, should have a physical examination to look for signs of joint instability.
Other complications — Less serious complications include those affecting vision and hearing, and those that lead to other non-life-threatening conditions.
Intellectual disability — Almost all babies born with Down syndrome are intellectually disabled, but the degree of impairment can vary a lot. Despite the disability, most children with DS can learn basic tasks; they just take a little longer than other babies to do so. Table 2 lists the average ages at which babies with Down syndrome reach certain milestones (table 2).
Height and weight — Babies with Down syndrome are usually smaller than other babies, and they have smaller heads. They may also grow more slowly, and may never reach the same heights that normal children do.
Although children with Down syndrome grow less than usual, they tend to gain more weight possibly from a slower metabolism. As a result, parents need to guard against obesity by encouraging exercise and, if necessary, limiting the amount of food the child eats.
Vision — Most children with Down syndrome have some sort of vision problem, such as nearsightedness, farsightedness, or astigmatism (an abnormal curvature of the eye that causes blurred vision). They may also have weak eye muscles (cross-eyed) or have abnormal eye movements that impair vision. Glasses can often correct these problems.
Hearing loss — Nearly 80 percent of people with Down syndrome develop some degree of hearing impairment, sometimes requiring a hearing aid. Children with Down syndrome are also much more prone than other children to having ear infections. (See "Patient information: Ear infections (otitis media) in children (Beyond the Basics)".)
Skin — The majority of children with Down syndrome have a skin disorder of one sort or another. These disorders are not usually cause for concern. Examples include:
- Thickened skin on the palms and soles
- Flaky, scaling skin on the scalp and other oily parts of the body
- Pink marbling of the skin
- Dry skin
Behavior — Behavioral and psychological problems are more common among children with Down syndrome than among other children. Common disorders include attention deficit hyperactivity disorder, oppositional disorder, and aggressive disorders. As many as 7 percent of children with Down syndrome have an autism spectrum disorder. (See "Patient information: Symptoms and diagnosis of attention deficit hyperactivity disorder in children (Beyond the Basics)" and "Patient information: Autism spectrum disorder (Beyond the Basics)".)
Sleep apnea — Up to 75 percent of children with Down syndrome have sleep apnea, a sleep disorder that causes them to intermittently stop breathing while asleep. The condition is often tied to being overweight, but among children with Down syndrome, it happens even when weight is not an issue. (See "Management of obstructive sleep apnea in children".)
Fertility — Women with Down syndrome are usually fertile and may become pregnant. If you have a daughter, it's important to educate her about sex and how to take precautions against unwanted pregnancy. Nearly all men with Down syndrome are infertile. Still, if you have a son, it's important to educate him about appropriate behavior when it comes to sex.
DOWN SYNDROME DIAGNOSIS
Down syndrome is usually diagnosed during pregnancy. If Down syndrome is not diagnosed during pregnancy, healthcare providers can usually diagnose Down syndrome based on the infant's appearance. In such cases, the diagnosis should be confirmed using a blood test that examines the child's chromosomes (karyotype).
For a thorough discussion of prenatal Down syndrome diagnosis, (see "Patient information: Should I have a screening test for Down syndrome during pregnancy? (Beyond the Basics)").
DOWN SYNDROME TREATMENT
There is no treatment specifically for Down syndrome, but there are several important treatments for the complications of the condition. That's why it's important to have your child screened for these complications at regular intervals throughout his or her youth (table 1).
Having your child routinely screened can help ensure that he or she will get the appropriate treatment as soon as any Down syndrome-related complications arise. That can be important for serious complications as well as for not so serious ones. For example, your child may need corrective surgery to treat a heart defect. Or your child may need eyeglasses or hearing aids — not only to improve vision or hearing, but also to maximize his or her ability to learn and understand.
DOWN SYNDROME PROGNOSIS
The prognosis for a child with Down syndrome used to be pretty grim. In 1983 the average lifespan of a person with the condition was just 25 years. Thanks to advances in the treatment and screening of people with Down syndrome, the landscape has changed. Just 14 years later, in 1997, the average lifespan had nearly doubled to 49 years.
As medicine continues to evolve, the outlook for people with Down syndrome will probably keep improving. Even now, many children with the condition go on to have full and happy lives, so long as they have the right support.
WHERE TO GET MORE INFORMATION
Your healthcare provider is the best source of information for questions and concerns related to your medical problem.
This article will be updated as needed on our web site (www.uptodate.com/patients). Related topics for patients, as well as selected articles written for healthcare professionals, are also available. Some of the most relevant are listed below.
Patient level information — UpToDate offers two types of patient education materials.
The Basics — The Basics patient education pieces answer the four or five key questions a patient might have about a given condition. These articles are best for patients who want a general overview and who prefer short, easy-to-read materials.
Patient information: Down syndrome (The Basics)
Patient information: Should I have a screening test for Down syndrome during pregnancy? (The Basics)
Patient information: Newborn appearance (The Basics)
Beyond the Basics — Beyond the Basics patient education pieces are longer, more sophisticated, and more detailed. These articles are best for patients who want in-depth information and are comfortable with some medical jargon.
Patient information: Should I have a screening test for Down syndrome during pregnancy? (Beyond the Basics)
Patient information: Celiac disease in children (Beyond the Basics)
Patient information: Ear infections (otitis media) in children (Beyond the Basics)
Patient information: Symptoms and diagnosis of attention deficit hyperactivity disorder in children (Beyond the Basics)
Patient information: Autism spectrum disorder (Beyond the Basics)
Professional level information — Professional level articles are designed to keep doctors and other health professionals up-to-date on the latest medical findings. These articles are thorough, long, and complex, and they contain multiple references to the research on which they are based. Professional level articles are best for people who are comfortable with a lot of medical terminology and who want to read the same materials their doctors are reading.
Down syndrome: Clinical features and diagnosis
Down syndrome: Management
Management of obstructive sleep apnea in children
The following organizations also provide reliable health information.