Symptoms
Causes
How many people are affected by or at risk for Down syndrome?
Screening and Diagnosis
What conditions or disorders are commonly associated with Down syndrome?
Treatment Options
Down syndrome describes a set of cognitive and physical symptoms that result from an extra copy or part of a copy of chromosome 21.
Chromosomes carry the genes that tell the body to develop in certain ways and to perform certain functions. Most cells of the human body contain 23 pairs of chromosomes-one set of chromosomes from each parent- for a total of 46 chromosomes. People with Down syndrome have either a full or partial extra copy of chromosome 21, for a total of 47 chromosomes. (The syndrome is sometimes called 47,XX,+21 or 47,XY,+21 to indicate the extra chromosome 21.)
The extra chromosome disrupts the normal course of development and results in the physical features and intellectual and developmental disabilities associated with the syndrome.
The degree of intellectual disability in people with Down syndrome varies but is usually mild to moderate. Generally, children with Down syndrome reach key developmental milestones later than other children.People with the syndrome also are more likely to be born with heart abnormalities, and they are at increased risk for developing hearing and vision problems, Alzheimer disease, and other conditions. However, with appropriate support and treatment, many people with Down syndrome lead happy, productive lives. In recent decades, life expectancy for people with Down syndrome has increased dramatically, from 25 years in 1983 to 60 years today.
Down syndrome is named after John Langdon Down, the first physician to describe the syndrome systematically.
The symptoms of Down syndrome vary from person to person, and people with Down syndrome may have different problems at different times of their lives.
Common physical signs of Down syndrome include:
In addition, physical development in children with Down syndrome is often slower than development of children without Down syndrome. For example, because of poor muscle tone, a child with Down syndrome may be slow to learn to turn over, sit, stand, and walk. Despite these delays, children with Down syndrome can learn to participate in physical exercise activities like other children. It may take children with Down syndrome longer than other children to reach developmental milestones, but they will eventually meet many of these milestones.
Cognitive impairment, problems with thinking and learning, is common in people with Down syndrome and usually ranges from mild to moderate. Only rarely is Down syndrome associated with severe cognitive impairment.
Other common cognitive and behavioral problems may include:
Most children with Down syndrome develop the communication skills they need, although it might take longer for them to do so compared with other children. Early, ongoing speech and language interventions to encourage expressive language and improve speech are particularly helpful.
?Parents and families of children with Down syndrome can connect with other families and people with Down syndrome from around the world to learn more and share information. The NICHD-led DS-Connect is a safe and secure registry to help families and researchers identify similarities and differences in the physical and developmental symptoms and milestones of people with Down syndrome and guide future research. Learn more about DS-Connect: The Down Syndrome Registry?.
People with Down syndrome are at increased risk for a range of other health conditions, including autism spectrum disorders, problems with hormones and glands, hearing loss, vision problems, and heart abnormalities. Learn more about these other conditions in the What conditions or disorders are commonly associated with Down syndrome? section.
Down syndrome is caused by a random error in cell division that results in the presence of an extra copy of chromosome 21.
The type of error is called nondisjunction (pronounced non-dis-JUHNGK-shuhn). Usually when one cell divides in two, pairs of chromosomes are split so that one of the pair goes to one cell, and the other from the pair goes to the other cell. In nondisjunction, something goes wrong and both chromosomes from one pair go into one cell and no chromosomes for that pair go into the other cell.
Most of the time, the error occurs at random during the formation of an egg or sperm. To date, no behavioral activity of the parents or environmental factor is known to cause Down syndrome.
After much research on these cell division errors, researchers know that:
The NICHD launched DS-Connect as a safe and secure online registry for people with Down syndrome, their families, and researchers to share information and participate in clinical trials or research. As the registry grows, families and researchers learn more about Down syndrome and identify similarities and differences in the symptoms and treatment of people with Down syndrome from around the world. The information collected helps guide future research and treatment.
Research shows that three types of chromosomal changes can lead to Down syndrome.
According to the Centers for Disease Control and Prevention, approximately 6,000 babies are born in the United States each year with Down syndrome, or approximately 1 out of every 691 live births.
Down syndrome is the most frequent chromosomal cause of mild to moderate intellectual disability, and it occurs in all ethnic and economic groups. Currently, more than 400,000 people are living with Down syndrome in the United States, according to the National Down Syndrome Society.
Researchers know some, but not all, of the risk factors for Down syndrome. For example, parents who have a child with Down syndrome or another chromosomal disorder, or who have a chromosomal disorder themselves, are more likely to have a child with Down syndrome.
In the United States, demographic factors also affect the risk for a child to be born with Down syndrome. These factors include geographic region, maternal education, marital status, and Hispanic ethnicity.
Because the likelihood that an egg will contain an extra copy of chromosome 21 increases significantly as a woman ages, older women are much more likely than younger women to give birth to an infant with Down syndrome. Although women older than 35 years of age make up less than 15% of all births in the United States each year, about 40% of babies with Down syndrome are born to women in this age group.
This likelihood increases as age increases. Following are the rates of Down syndrome for select ages:
Health care providers can check for Down syndrome during pregnancy or after a child is born. There are two types of tests for Down syndrome during pregnancy:
The American Congress of Obstetricians and Gynecologists (ACOG) recommends that all pregnant women be offered a Down syndrome screening test.
There are several options for Down syndrome prenatal screening. These include:
If a woman is pregnant with twins or triplets, a blood test will not be as reliable because the substances from a Down syndrome fetus may be harder to detect.
If a screening test suggests the likelihood of Down syndrome, a diagnostic test can be performed. ACOG recommends that pregnant women of all ages be given the option of skipping the screening test and getting a diagnostic test first. Until recently, only women over age 35 and other at-risk women were offered this option because diagnostic tests carry a slight risk of miscarriage. Before having diagnostic testing, a pregnant woman and her family may want to meet with a genetic counselor to discuss their family history and the risks and benefits of testing in their specific situation.
Diagnostic testing for Down syndrome involves removing a sample of genetic material. After it is removed, the sample is checked for extra material from chromosome 21, which may indicate that a fetus has Down syndrome. Parents usually get the results of the test a week or two later. The following procedures are used to extract samples.
Prenatal diagnostic testing does involve some risk to the mother and fetus, including risk of miscarriage that ranges from less than 1% to 2%. If you and your family are considering prenatal diagnostic testing for Down syndrome, discuss all the risks and benefits with your health care provider.
A pregnant woman who is at risk for having an infant with Down syndrome also can have a chromosomal test using her blood. A mother's blood carries DNA from the fetus, which may show extra chromosome 21 material. A more invasive test then would usually confirm the blood test.
Another approach to diagnosis is used in conjunction with in vitro fertilization. Preimplantation genetic diagnosis (PGD) allows clinicians to detect chromosome imbalances or other genetic conditions in a fertilized egg before it is implanted into the uterus.
This technique is useful mostly for couples who are at risk of passing on a variety of genetic conditions, including X-linked disorders, as well as couples who have suffered repeated spontaneous pregnancy losses, sub-fertile couples, or those at risk for single-gene disorders.
Those interested in PGD should have genetic counseling and should consider close monitoring and additional testing during their pregnancies, given some increased risk of chromosomal abnormalities arising secondary to the in vitro fertilization process.
A diagnosis of Down syndrome after birth is often based initially on physical signs of the syndrome.
But because individuals with Down syndrome may not have these symptoms, and because many of these symptoms are common in the general population, the health care provider will take a sample of the baby's blood to confirm the diagnosis. The blood sample is analyzed to determine the number of the baby's chromosomes.
There is no single, standard treatment for Down syndrome. Treatments are based on each individual's physical and intellectual needs as well as his or her personal strengths and limitations. People with Down syndrome can receive proper care while living at home and in the community.
A child with Down syndrome likely will receive care from a team of health professionals, including, but not limited to, physicians, special educators, speech therapists, occupational therapists, physical therapists, and social workers. All professionals who interact with children with Down syndrome should provide stimulation and encouragement.
People with Down syndrome are at a greater risk for a number of health problems and conditions than are those who do not have Down syndrome. Many of these associated conditions may require immediate care right after birth, occasional treatment throughout childhood and adolescence, or long-term treatments throughout life. For example, an infant with Down syndrome may need surgery a few days after birth to correct a heart defect; or a person with Down syndrome may have digestive problems that require a lifelong special diet.
Children, teens, and adults with Down syndrome also need the same regular medical care as those without the condition, from well-baby visits and routine vaccinations as infants to reproductive counseling and cardiovascular care later in life. Like other people, they also benefit from regular physical activity and social activities.
"Early intervention" refers to a range of specialized programs
and resources that professionals provide to very young children with
Down syndrome and their families. These professionals may include
special educators, speech therapists, occupational therapists, physical
therapists, and social workers. Research indicates that early intervention improves outcomes
for children with Down syndrome. This
assistance can begin shortly after birth and often continues until a
child reaches age 3. After that age, most
children receive interventions and treatment through their local school
district. Most children with Down syndrome are eligible for free,
appropriate public education under federal law. Public Law 105-17
(2004): The Individuals with Disabilities Education Act (IDEA) makes it
possible for children with disabilities to get free educational
services and devices to help them learn as much as they can. Each child
is entitled to these services from birth through the end of high
school, or until age 21, whichever comes first. Most early intervention
programs fall under this legislation. The National Early Childhood Technical Assistance Center, run
by the U.S. Department of Education, provides information and resources
for parents and families looking for early intervention programs. Visit
http://www.nectac.org The law also states that each child must be taught in the
least restrictive environment that is appropriate. This statement does
not mean that each child will be placed in a regular classroom.
Instead, educators will work to provide an environment that best fits
the child's needs and skills. The following information may be helpful for those considering
educational assistance programs for a child with Down syndrome: The U.S. Department of Education funds the Parent Center
Network, which provides resources, contacts, and assistance for parents
and families trying to navigate special education programs. Visit
http://www.parentcenternetwork.org/ A variety of therapies can be used in early intervention
programs and throughout a person's life to promote the greatest
possible development, independence, and productivity. Some of these
therapies are listed below. Some people with Down syndrome take amino acid supplements or
drugs that affect their brain activity. However, many of the recent
clinical trials of these treatments were poorly controlled and revealed
adverse effects from these treatments. Since then, newer psychoactive
drugs that are much more specific have been developed. No controlled
clinical studies of these medications for Down syndrome have
demonstrated their safety and efficacy, however. Many studies of drugs to treat symptoms of dementia in Down
syndrome have included only a few participants. The results of these
studies have not shown clear benefits of these drugs, either.
Similarly, studies of antioxidants for dementia in Down syndrome have
shown that these supplements are safe, but not effective.Early Intervention and Educational Therapy
for more information.
Additional early intervention resources are available at
http://day2dayparenting.com/category/child-development-2/special-needs-diagnoses/
, and at
http://www.familyvoices.org
.
for more information.
Treatment Therapies
Drugs and Supplements
Some of the conditions that occur more often among children with Down syndrome include:
-NIH