# data[].attributes.body
There are many different treatments for Down's Syndrome Such as:
- Physical Therapy for increasing Motor Skills
- Speech therapy to improve their communication skills
- Occupational Therapy to help them get through and accomplish their every-day life skills
- Emotional and Behavioral Therapy to help manage undesirable behavior

https://www.nichd.nih.gov/health/topics/down/conditioninfo/treatments

# data[].attributes.attachment_link.title
What are common treatments for Down syndrome?

# data[].attributes.attachment_link.description
Treatments are based on each individual’s physical and intellectual needs, as well as his or her personal strengths and limitations.

# data[].attributes.body
The development and characterization of mouse models for understanding Down syndrome and testing the effectiveness of various medications and the exploration of a variety of health systems research questions.

# data[].attributes.attachment_link.readable_text
Down syndrome is a chromosomal disorder caused by an error in cell division that results in the presence of an additional copy of chromosome 21 (trisomy 21) or additional chromosomal 21 material. Named after John Langdon Down, the first physician to describe the syndrome systematically, Down syndrome is the most frequent chromosomal cause of mild to moderate intellectual disability. It occurs in all ethnic and economic groups. People with the syndrome also are at a greater risk for many other conditions, such as congenital heart disease, hearing loss, leukemia, and dementia and memory loss similar to Alzheimer disease.

The NICHD has conducted and supported Down syndrome research since its founding, including development of animal models to help study the syndrome, examination of specific genes and gene groups that may play a role in the syndrome, understanding how maternal age plays a role in the disorder, and development of new methods of diagnosis prenatally and postnatally. Additional research activities are described below.

Institute Activities and Advances

The Institute's portfolio covers a broad range of research areas, including the causes, treatment, and prevention of Down syndrome.

New NIH Initiative: NICHD is pleased to be part of INCLUDE (INvestigation of Co-occurring conditions across the Lifespan to Understand Down syndromE), an NIH-wide initiative that launched in June 2018 in support of a Congressional directive in the fiscal year 2018 Omnibus Appropriations. The project aims to understand critical health and quality-of-life needs for individuals with Down syndrome, with the aim of yielding scientific discoveries to improve the health, well-being, and neurodevelopment of individuals with Down syndrome, as well as their risk and resilience common diseases that they share with individuals who do not have Down syndrome. INCLUDE will investigate conditions that affect individuals with Down syndrome and the general population, such as Alzheimer's disease/dementia, autism, cataracts, celiac disease, congenital heart disease, and diabetes.

Since 2011, the Institute has led the Down Syndrome Consortium, a public-private collaboration that provides a forum for promoting the Down Syndrome Directions: NIH Research Plan on Down Syndrome (2014) and fosters the exchange of information on biomedical and biobehavioral research on the syndrome. Consortium members, who represent public and private organizations, work to avoid duplication of research efforts and to inform the Down syndrome community of research advances. In addition to the NICHD, the Consortium includes the following organizations (in alphabetical order):

In 2013, the Consortium launched its Down syndrome registry, DS-Connect®, which facilitates contacts and information sharing among people with Down syndrome and their family members, researchers, and parent and support groups safely and confidentially. Creation of this registry was one of the principal recommendations of the Down Syndrome Research Plan.

Read the What is DS-Connect®: The Down Syndrome Registry? text alternative.

Read the Creating an Account in DS-Connect®: The Down Syndrome Registry text alternative.

The Institute has also played a lead role in the trans-NIH Working Group on Down Syndrome, which developed the Research Plan, and aims to coordinate research activities across the NIH.

Some of the Institute's work related to Down syndrome is supported through its Intellectual and Developmental Disabilities Branch (IDDB). A key focus for the IDDB is exploring treatments for Down syndrome, including agents that improve intellectual development and cognitive performance.

The Repository for Mouse Models for Cytogenetic Disorders , a distribution center supported by the NICHD, provides mice for research on Down syndrome and other disorders. Because of similarities between certain mouse and human chromosomes, mouse models have allowed significant advances in understanding potential treatments for Down syndrome. For example, researchers currently are studying the use of the drug memantine, which supports cognition in mice and is approved for treating Alzheimer's dementia in humans, to improve the cognitive abilities of young adults with Down syndrome.

Improvements in learning in a Down syndrome animal model

Using a mouse model for Down syndrome, NICHD researchers showed that by administering neuroprotective peptides (small protein sub units) to mice before birth, they perform better on memory and learning tasks as adults. The peptides, NAP and SAL, are sub units of two proteins that are important in brain development because they enhance the ability of brain cells to receive and transmit signals, and enable them to survive. The mice in the study had an extra copy of mouse chromosome 16, which has counterparts to 55% of the genes on human chromosome 21. Mice with the extra chromosomal material that were treated with NAP and SAL in the womb learned as well as mice that did not have the extra chromosome and significantly faster than mice with the extra chromosome that were treated with saline solution (placebo).

In an earlier study, NICHD researchers showed that when mice with the extra copy of chromosome 16 were treated with NAP and SAL in the womb, they achieved developmental milestones earlier than did untreated mice. In this earlier study, the researchers examined developmental milestones for sensory, motor skill, and muscle tone in the first three weeks of life. Together these study findings show that NAP and SAL treatments improve both physical development and learning ability in a mouse model for Down syndrome.

Other research focuses on the causes and pathophysiology of Down syndrome. The IDDB supports a broad range of activities in this area, including explorations of the signaling pathways, metabolic processes, and mitochondrial functions that affect the development of people with Down syndrome.

Some other recent scientific advances related to Down syndrome include:

An assessment of gastrointestinal anomalies by sex, race, and ethnicity (PMID: 19021635)

Identification of modifier genes located on other chromosomes that affect variability in Down syndrome features

Evidence from animal models of genes involved in craniofacial and brain development (PMID: 19764029) (PMID: 20639873) (PMID: 17431903)

Identification of specific genes that are candidates for the features of Down syndrome (PMID: 12466854)

Assessment of the benefits of early intervention programs (PMID: 21532932)

Other organizational units also support or conduct research related to Down syndrome. For example:

The NICHD Developmental Biology and Structural Variation Branch examines areas relevant to normal and abnormal development, such as the processes, patterns, and genetics of organ and central nervous system development. The Branch also supports research on epigenetic and genomic regulation of gene expression, and on developmental neurobiology.

The Institute's Section on Gamete Development, which is part of the Division of Intramural Research (DIR), researches meiosis (a cellular process of reduction and division, pronounced mahy-OH-sis) to understand the mechanisms that lead to chromosome missegregation, which can cause Down syndrome and other disorders.

In addition, the DIR's Section on Implantation and Oocyte Physiology validates model organisms for their use in studying chromosomal abnormalities in human embryos and identifying new tests to detect chromosomal abnormalities in early embryos.

Research in Down syndrome has the potential to improve the clinical care and quality of life for individuals with Down syndrome and their families. Areas of current and future research activity include the development of clinical trials for testing medical interventions and therapeutics in those with Down syndrome, the development and characterization of mouse models for understanding Down syndrome and testing the effectiveness of various medications, and the exploration of a variety of health systems' research questions.

For example:

Recent studies explore the neurodevelopmental impact of congenital heart defects on people with Down syndrome.

Based on recent findings, scientists believe that short chromosome 21 telomere length may become a biomarker for early stages of dementia in people with Down syndrome, which currently can be difficult to identify.

Researchers are assessing ways to improve communication between parents and children with Down syndrome.

One study is testing a portable electronic device designed to motivate increased physical activity among people with intellectual and developmental disabilities (IDDs) and to monitor their progress.

Studies focused on reducing an imbalance between excitation and inhibition in the nervous system have provided some evidence of lasting effects.

Research on choline supplementation during pregnancy has provided evidence of lasting effects on memory and cognition.

Researchers are exploring ways to predict obstructive sleep apnea in people with Down syndrome.

Future research related to health care disparities and Down syndrome focuses on ways to increase access to medical care and to increase life expectancy, particularly among underrepresented minorities. Another issue that needs to be addressed is the dearth of adult health care providers with expertise to provide appropriate medical care for those with Down syndrome who are now adults. To identify ways to ease the transition between adolescent care for those with Down syndrome and adult lifestyles, the following questions should be considered:

What are the factors that facilitate and influence successful transition?

What are the roles of youth and families in the transition process?

What are the skills and knowledge they need?

What are the indicators of a successful system for transition?

Other Activities and Advances

To achieve its goals related to Down syndrome research, the NICHD supports and participates in a variety of other activities, including NIH-wide efforts. Some of these are listed below.

# data[].attributes.attachment_link.title
Down Syndrome: Research Activities and Scientific Advances

# data[].attributes.attachment_link.description
Down syndrome is a chromosomal disorder caused by an error in cell division that results in the presence of an additional copy of chromosome 21 (trisomy 21) or additional chromosomal 21 material. Named after John Langdon Down, the first physician to describe the syndrome systematically, Down syndrome is the most frequent chromosomal cause of mild to moderate intellectual disability.

# data[].attributes.headline
How many people does this disorder affect

# data[].attributes.subject
How many people does this disorder affect

# data[].attributes.body
Down syndrome remains the most common chromosomal condition diagnosed in the US. Each year around 6,000 babies born in the United States have Down syndrome. This means that Down syndrome occurs in about 1 in every 700 babies.

# data[].attributes.attachment_link.provider_name
Centers for Disease Control and Prevention

# data[].attributes.attachment_link.readable_text
What is Down Syndrome?

Down syndrome is a condition in which a person has an extra chromosome. Chromosomes are small "packages" of genes in the body. They determine how a baby's body forms and functions as it grows during pregnancy and after birth. Typically, a baby is born with 46 chromosomes. Babies with Down syndrome have an extra copy of one of these chromosomes, chromosome 21. A medical term for having an extra copy of a chromosome is 'trisomy.' Down syndrome is also referred to as Trisomy 21. This extra copy changes how the baby's body and brain develop, which can cause both mental and physical challenges for the baby.

Even though people with Down syndrome might act and look similar, each person has different abilities. People with Down syndrome usually have an IQ (a measure of intelligence) in the mildly-to-moderately low range and are slower to speak than other children.

Some common physical features of Down syndrome include:

A flattened face, especially the bridge of the nose

Almond-shaped eyes that slant up

A short neck

Small ears

A tongue that tends to stick out of the mouth

Tiny white spots on the iris (colored part) of the eye

Small hands and feet

A single line across the palm of the hand (palmar crease)

Small pinky fingers that sometimes curve toward the thumb

Poor muscle tone or loose joints

Shorter in height as children and adults

How Many Babies are Born with Down Syndrome?

Down syndrome remains the most common chromosomal condition diagnosed in the United States. Each year, about 6,000 babies born in the United States have Down syndrome. This means that Down syndrome occurs in about 1 in every 700 babies.

Types of Down Syndrome

There are three types of Down syndrome. People often can't tell the difference between each type without looking at the chromosomes because the physical features and behaviors are similar.

Trisomy 21: About 95% of people with Down syndrome have Trisomy 21. With this type of Down syndrome, each cell in the body has 3 separate copies of chromosome 21 instead of the usual 2 copies.

Translocation Down syndrome: This type accounts for a small percentage of people with Down syndrome (about 3%). This occurs when an extra part or a whole extra chromosome 21 is present, but it is attached or "trans-located" to a different chromosome rather than being a separate chromosome 21.

Mosaic Down syndrome: This type affects about 2% of the people with Down syndrome. Mosaic means mixture or combination. For children with mosaic Down syndrome, some of their cells have 3 copies of chromosome 21, but other cells have the typical two copies of chromosome 21. Children with mosaic Down syndrome may have the same features as other children with Down syndrome. However, they may have fewer features of the condition due to the presence of some (or many) cells with a typical number of chromosomes.

Causes and Risk Factors

The extra chromosome 21 leads to the physical features and developmental challenges that can occur among people with Down syndrome. Researchers know that Down syndrome is caused by an extra chromosome, but no one knows for sure why Down syndrome occurs or how many different factors play a role.

One factor that increases the risk for having a baby with Down syndrome is the mother's age. Women who are 35 years or older when they become pregnant are more likely to have a pregnancy affected by Down syndrome than women who become pregnant at a younger age.However, the majority of babies with Down syndrome are born to mothers less than 35 years old, because there are many more births among younger women.

Diagnosis

There are two basic types of tests available to detect Down syndrome during pregnancy: screening tests and diagnostic tests. A screening test can tell a woman and her healthcare provider whether her pregnancy has a lower or higher chance of having Down syndrome. Screening tests do not provide an absolute diagnosis, but they are safer for the mother and the developing baby. Diagnostic tests can typically detect whether or not a baby will have Down syndrome, but they can be more risky for the mother and developing baby. Neither screening nor diagnostic tests can predict the full impact of Down syndrome on a baby; no one can predict this.

Screening Tests

Screening tests often include a combination of a blood test, which measures the amount of various substances in the mother's blood (e.g., MS-AFP, Triple Screen, Quad-screen), and an ultrasound, which creates a picture of the baby. During an ultrasound, one of the things the technician looks at is the fluid behind the baby's neck. Extra fluid in this region could indicate a genetic problem. These screening tests can help determine the baby's risk of Down syndrome. Rarely, screening tests can give an abnormal result even when there is nothing wrong with the baby. Sometimes, the test results are normal and yet they miss a problem that does exist.

Diagnostic Tests

Diagnostic tests are usually performed after a positive screening test in order to confirm a Down syndrome diagnosis. Types of diagnostic tests include:

Chorionic villus sampling (CVS)-examines material from the placenta

Amniocentesis-examines the amniotic fluid (the fluid from the sac surrounding the baby)

Percutaneous umbilical blood sampling (PUBS)-examines blood from the umbilical cord

These tests look for changes in the chromosomes that would indicate a Down syndrome diagnosis.

Other Health Problems

Many people with Down syndrome have the common facial features and no other major birth defects. However, some people with Down syndrome might have one or more major birth defects or other medical problems. Some of the more common health problems among children with Down syndrome are listed below.

Hearing loss

Obstructive sleep apnea, which is a condition where the person's breathing temporarily stops while asleep

Ear infections

Eye diseases

Heart defects present at birth

Health care providers routinely monitor children with Down syndrome for these conditions.

Treatments

Down syndrome is a lifelong condition. Services early in life will often help babies and children with Down syndrome to improve their physical and intellectual abilities. Most of these services focus on helping children with Down syndrome develop to their full potential. These services include speech, occupational, and physical therapy, and 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.

Other Resources
The views of these organizations are their own and do not reflect the official position of CDC.
References

1. Mai CT, Isenburg JL, Canfield MA, Meyer RE, Correa A, Alverson CJ, Lupo PJ, Riehle‐Colarusso T, Cho SJ, Aggarwal D, Kirby RS. National population‐based estimates for major birth defects, 2010-2014. Birth Defects Research. 2019; 111(18): 1420-1435.

2. Shin M, Siffel C, Correa A. Survival of children with mosaic Down syndrome. Am J Med Genet A. 2010;152A:800-1.

3. Allen EG, Freeman SB, Druschel C, et al. Maternal age and risk for trisomy 21 assessed by the origin of chromosome nondisjunction: a report from the Atlanta and National Down Syndrome Projects. Hum Genet. 2009 Feb;125(1):41-52.

4. Ghosh S, Feingold E, Dey SK. Etiology of Down syndrome: Evidence for consistent association among altered meiotic recombination, nondisjunction, and maternal age across populations. Am J Med Genet A. 2009 Jul;149A(7):1415-20.

5. Sherman SL, Allen EG, Bean LH, Freeman SB. Epidemiology of Down syndrome. Ment Retard Dev Disabil Res Rev. 2007;13(3):221-7.

6. Adams MM, Erickson JD, Layde PM, Oakley GP. Down's syndrome. Recent trends in the United States. JAMA. 1981 Aug 14;246(7):758-60.

7. Olsen CL, Cross PK, Gensburg LJ, Hughes JP. The effects of prenatal diagnosis, population ageing, and changing fertility rates on the live birth prevalence of Down syndrome in New York State, 1983-1992. Prenat Diagn. 1996 Nov;16(11):991-1002.

8. Bull MJ, the Committee on Genetics. Health supervision for children with Down syndrome. Pediatrics. 2011;128:393-406.

# data[].attributes.attachment_link.keywords[]
national center on birth defects and developmental disabilities

# data[].attributes.attachment_link.description
Down syndrome is a condition in which a person has an extra chromosome. Chromosomes are small "packages" of genes in the body. They determine how a baby's body forms and functions as it grows during pregnancy and after birth. Typically, a baby is born with 46 chromosomes.

# data[].attributes.body
The Organization The National Downs Syndrome Society (NDSS). NDSS works to envision a world where all people with Down syndrome are able to have the opportunity to enhance their ways and qualities of life, pursuing their life aspirations and making sure that these people know that they are part a of welcoming community.

https://ndss.org/#:~:text=The%20National%20Down%20Syndrome%20Society,all%20individuals%20with%20Down%20syndrome.

# data[].attributes.attachment_link.readable_text
The NDSS Adult Summit covers aging and Down syndrome through a whole-person, comprehensive approach. Content will overlap ages and subject areas, providing attendees with information and practical resources. This conference is a great educational opportunity for individuals with Down syndrome and other disabilities, family members, and professionals.

# data[].attributes.attachment_link.description
The NDSS Adult Summit covers aging and Down syndrome through a whole-person, comprehensive approach. Content will overlap ages and subject areas, providing attendees with information and practical resources. This conference is a great educational opportunity for individuals with Down syndrome and other disabilities, family members, and professionals.

# data[].attributes.body
-Flattened face.
-Small head.
-Short neck.
-Protruding tongue.
-Upward slanting eye lids (palpebral fissures)
-Unusually shaped or small ears.
-Poor muscle tone.
-Broad, short hands with a single crease in the palm.

# data[].attributes.attachment_link.readable_text
Overview

Down syndrome is a genetic disorder caused when abnormal cell division results in an extra full or partial copy of chromosome 21. This extra genetic material causes the developmental changes and physical features of Down syndrome.

Down syndrome varies in severity among individuals, causing lifelong intellectual disability and developmental delays. It's the most common genetic chromosomal disorder and cause of learning disabilities in children. It also commonly causes other medical abnormalities, including heart and gastrointestinal disorders.

Better understanding of Down syndrome and early interventions can greatly increase the quality of life for children and adults with this disorder and help them live fulfilling lives.

Symptoms

Each person with Down syndrome is an individual - intellectual and developmental problems may be mild, moderate or severe. Some people are healthy while others have significant health problems such as serious heart defects.

Children and adults with Down syndrome have distinct facial features. Though not all people with Down syndrome have the same features, some of the more common features include:

Flattened face

Small head

Short neck

Protruding tongue

Upward slanting eye lids (palpebral fissures)

Unusually shaped or small ears

Poor muscle tone

Broad, short hands with a single crease in the palm

Relatively short fingers and small hands and feet

Excessive flexibility

Tiny white spots on the colored part (iris) of the eye called Brushfield's spots

Short height

Infants with Down syndrome may be average size, but typically they grow slowly and remain shorter than other children the same age.

Intellectual disabilities

Most children with Down syndrome have mild to moderate cognitive impairment. Language is delayed, and both short and long-term memory is affected.

When to see a doctor

Children with Down syndrome usually are diagnosed before or at birth. However, if you have any questions regarding your pregnancy or your child's growth and development, talk with your doctor.

Causes

Human cells normally contain 23 pairs of chromosomes. One chromosome in each pair comes from your father, the other from your mother.

Down syndrome results when abnormal cell division involving chromosome 21 occurs. These cell division abnormalities result in an extra partial or full chromosome 21. This extra genetic material is responsible for the characteristic features and developmental problems of Down syndrome. Any one of three genetic variations can cause Down syndrome:

Trisomy 21. About 95 percent of the time, Down syndrome is caused by trisomy 21 - the person has three copies of chromosome 21, instead of the usual two copies, in all cells. This is caused by abnormal cell division during the development of the sperm cell or the egg cell.

Mosaic Down syndrome. In this rare form of Down syndrome, a person has only some cells with an extra copy of chromosome 21. This mosaic of normal and abnormal cells is caused by abnormal cell division after fertilization.

Translocation Down syndrome. Down syndrome can also occur when a portion of chromosome 21 becomes attached (translocated) onto another chromosome, before or at conception. These children have the usual two copies of chromosome 21, but they also have additional genetic material from chromosome 21 attached to another chromosome.

There are no known behavioral or environmental factors that cause Down syndrome.

Is it inherited?

Most of the time, Down syndrome isn't inherited. It's caused by a mistake in cell division during early development of the fetus.

Translocation Down syndrome can be passed from parent to child. However, only about 3 to 4 percent of children with Down syndrome have translocation and only some of them inherited it from one of their parents.

When balanced translocations are inherited, the mother or father has some rearranged genetic material from chromosome 21 on another chromosome, but no extra genetic material. This means he or she has no signs or symptoms of Down syndrome, but can pass an unbalanced translocation on to children, causing Down syndrome in the children.

Risk factors

Some parents have a greater risk of having a baby with Down syndrome. Risk factors include:

Advancing maternal age. A woman's chances of giving birth to a child with Down syndrome increase with age because older eggs have a greater risk of improper chromosome division. A woman's risk of conceiving a child with Down syndrome increases after 35 years of age. However, most children with Down syndrome are born to women under age 35 because younger women have far more babies.

Being carriers of the genetic translocation for Down syndrome. Both men and women can pass the genetic translocation for Down syndrome on to their children.

Having had one child with Down syndrome. Parents who have one child with Down syndrome and parents who have a translocation themselves are at an increased risk of having another child with Down syndrome. A genetic counselor can help parents assess the risk of having a second child with Down syndrome.

Complications

People with Down syndrome can have a variety of complications, some of which become more prominent as they get older. These complications can include:

Heart defects. About half the children with Down syndrome are born with some type of congenital heart defect. These heart problems can be life-threatening and may require surgery in early infancy.

Gastrointestinal (GI) defects. GI abnormalities occur in some children with Down syndrome and may include abnormalities of the intestines, esophagus, trachea and anus. The risk of developing digestive problems, such as GI blockage, heartburn (gastroesophageal reflux) or celiac disease, may be increased.

Immune disorders. Because of abnormalities in their immune systems, people with Down syndrome are at increased risk of developing autoimmune disorders, some forms of cancer, and infectious diseases, such as pneumonia.

Sleep apnea. Because of soft tissue and skeletal changes that lead to the obstruction of their airways, children and adults with Down syndrome are at greater risk of obstructive sleep apnea.

Obesity. People with Down syndrome have a greater tendency to be obese compared with the general population.

Spinal problems. Some people with Down syndrome may have a misalignment of the top two vertebrae in the neck (atlantoaxial instability). This condition puts them at risk of serious injury to the spinal cord from overextension of the neck.

Leukemia. Young children with Down syndrome have an increased risk of leukemia.

Dementia. People with Down syndrome have a greatly increased risk of dementia - signs and symptoms may begin around age 50. Having Down syndrome also increases the risk of developing Alzheimer's disease.

Other problems. Down syndrome may also be associated with other health conditions, including endocrine problems, dental problems, seizures, ear infections, and hearing and vision problems.

For people with Down syndrome, getting routine medical care and treating issues when needed can help with maintaining a healthy lifestyle.

Life expectancy

Life spans have increased dramatically for people with Down syndrome. Today, someone with Down syndrome can expect to live more than 60 years, depending on the severity of health problems.

Prevention

There's no way to prevent Down syndrome. If you're at high risk of having a child with Down syndrome or you already have one child with Down syndrome, you may want to consult a genetic counselor before becoming pregnant.

A genetic counselor can help you understand your chances of having a child with Down syndrome. He or she can also explain the prenatal tests that are available and help explain the pros and cons of testing.

# data[].attributes.attachment_link.description
Down syndrome is a genetic disorder caused when abnormal cell division results in extra genetic material from chromosome 21.

# data[].attributes.headline
Most cases of Down's syndrome are not inherited. The condition is cause by Trisomy 21 which is not inherited. Trisomy 21 is a chromosomal abnormality that occurs during the formation of reproductive cells in a parent. The abnormality can occur in both egg and sperm cells.   

# data[].attributes.subject
Most cases of Down's syndrome are not inherited. The condition is cause by Trisomy 21 which is not inherited. Trisomy 21 is a chromosomal abnormality that occurs during the formation of reproductive cells in a parent. The abnormality can occur in both egg and sperm cells.   

# data[].attributes.body
https://medlineplus.gov/genetics/condition/down-syndrome/#:~:text=Inheritance&text=Most%20cases%20of%20Down%20syndrome%20are%20not%20inherited.,occasionally%20o

# data[].attributes.attachment_link.readable_text
To use the sharing features on this page, please enable JavaScript.

Description

Down syndrome is a chromosomal condition that is associated with intellectual disability, a characteristic facial appearance, and weak muscle tone (hypotonia) in infancy. All affected individuals experience cognitive delays, but the intellectual disability is usually mild to moderate.

People with Down syndrome often have a characteristic facial appearance that includes a flattened appearance to the face, outside corners of the eyes that point upward ( upslanting palpebral fissures), small ears, a short neck, and a tongue that tends to stick out of the mouth. Affected individuals may have a variety of birth defects. Many people with Down syndrome have small hands and feet and a single crease across the palms of the hands. About half of all affected children are born with a heart defect. Digestive abnormalities, such as a blockage of the intestine, are less common.

Individuals with Down syndrome have an increased risk of developing several medical conditions. These include gastroesophageal reflux, which is a backflow of acidic stomach contents into the esophagus, and celiac disease, which is an intolerance of a wheat protein called gluten. About 15 percent of people with Down syndrome have an underactive thyroid gland (hypothyroidism). The thyroid gland is a butterfly-shaped organ in the lower neck that produces hormones. Individuals with Down syndrome also have an increased risk of hearing and vision problems. Additionally, a small percentage of children with Down syndrome develop cancer of blood-forming cells ( leukemia).

Delayed development and behavioral problems are often reported in children with Down syndrome. Affected individuals can have growth problems and their speech and language develop later and more slowly than in children without Down syndrome. Additionally, speech may be difficult to understand in individuals with Down syndrome. Behavioral issues can include attention problems, obsessive/compulsive behavior, and stubbornness or tantrums. A small percentage of people with Down syndrome are also diagnosed with developmental conditions called autism spectrum disorders, which affect communication and social interaction.

People with Down syndrome often experience a gradual decline in thinking ability (cognition) as they age, usually starting around age 50. Down syndrome is also associated with an increased risk of developing Alzheimer disease, a brain disorder that results in a gradual loss of memory, judgment, and ability to function. Approximately half of adults with Down syndrome develop Alzheimer disease. Although Alzheimer disease is usually a disorder that occurs in older adults, people with Down syndrome commonly develop this condition earlier, in their fifties or sixties.

Frequency

Down syndrome occurs in about 1 in 700 newborns. About 5,300 babies with Down syndrome are born in the United States each year, and approximately 200,000 people in this country have the condition. Although women of any age can have a child with Down syndrome, the chance of having a child with this condition increases as a woman gets older.

Causes

Most cases of Down syndrome result from trisomy 21, which means each cell in the body has three copies of chromosome 21 instead of the usual two copies.

Less commonly, Down syndrome occurs when part of chromosome 21 becomes attached ( translocated) to another chromosome during the formation of reproductive cells (eggs and sperm) in a parent or very early in fetal development. Affected people have two normal copies of chromosome 21 plus extra material from chromosome 21 attached to another chromosome, resulting in three copies of genetic material from chromosome 21. Affected individuals with this genetic change are said to have translocation Down syndrome.

A very small percentage of people with Down syndrome have an extra copy of chromosome 21 in only some of the body's cells. In these people, the condition is called mosaic Down syndrome.

Researchers believe that having extra copies of genes on chromosome 21 disrupts the course of normal development, causing the characteristic features of Down syndrome and the increased risk of health problems associated with this condition.

Inheritance

Most cases of Down syndrome are not inherited. When the condition is caused by trisomy 21, the chromosomal abnormality occurs as a random event during the formation of reproductive cells in a parent. The abnormality usually occurs in egg cells, but it occasionally occurs in sperm cells. An error in cell division called nondisjunction results in a reproductive cell with an abnormal number of chromosomes. For example, an egg or sperm cell may gain an extra copy of chromosome 21. If one of these atypical reproductive cells contributes to the genetic makeup of a child, the child will have an extra chromosome 21 in each of the body's cells.

People with translocation Down syndrome can inherit the condition from an unaffected parent. The parent carries a rearrangement of genetic material between chromosome 21 and another chromosome. This rearrangement is called a balanced translocation. No genetic material is gained or lost in a balanced translocation, so these chromosomal changes usually do not cause any health problems. However, as this translocation is passed to the next generation, it can become unbalanced. People who inherit an unbalanced translocation involving chromosome 21 may have extra genetic material from chromosome 21, which causes Down syndrome.

Like trisomy 21, mosaic Down syndrome is not inherited. It occurs as a random event during cell division early in fetal development. As a result, some of the body's cells have the usual two copies of chromosome 21, and other cells have three copies of this chromosome.

Additional Information & Resources

Patient Support and Advocacy Resources

Catalog of Genes and Diseases from OMIM

References

Antonarakis SE, Lyle R, Dermitzakis ET, Reymond A, Deutsch S. Chromosome 21 and down syndrome: from genomics to pathophysiology. Nat Rev Genet. 2004 Oct;5(10):725-38. doi: 10.1038/nrg1448. Citation on PubMed

Capone G, Goyal P, Ares W, Lannigan E. Neurobehavioral disorders in children, adolescents, and young adults with Down syndrome. Am J Med Genet C Semin Med Genet. 2006 Aug 15;142C(3):158-72. doi: 10.1002/ajmg.c.30097. Citation on PubMed

Carter JC, Capone GT, Gray RM, Cox CS, Kaufmann WE. Autistic-spectrum disorders in Down syndrome: further delineation and distinction from other behavioral abnormalities. Am J Med Genet B Neuropsychiatr Genet. 2007 Jan 5;144B(1):87-94. doi: 10.1002/ajmg.b.30407. Citation on PubMed

Chapman RS, Hesketh LJ. Behavioral phenotype of individuals with Down syndrome. Ment Retard Dev Disabil Res Rev. 2000;6(2):84-95. doi: 10.1002/1098-2779(2000)6:23.0.CO;2-P. Citation on PubMed

Cohen WI. Current dilemmas in Down syndrome clinical care: celiac disease, thyroid disorders, and atlanto-axial instability. Am J Med Genet C Semin Med Genet. 2006 Aug 15;142C(3):141-8. doi: 10.1002/ajmg.c.30102. Citation on PubMed

de Graaf G, Buckley F, Skotko BG. Estimates of the live births, natural losses, and elective terminations with Down syndrome in the United States. Am J Med Genet A. 2015 Apr;167A(4):756-67. doi: 10.1002/ajmg.a.37001. Citation on PubMed

de Graaf G, Buckley F, Skotko BG. Estimation of the number of people with Down syndrome in the United States. Genet Med. 2017 Apr;19(4):439-447. doi: 10.1038/gim.2016.127. Epub 2016 Sep 8. Citation on PubMed

Kumin L. Speech intelligibility and childhood verbal apraxia in children with Down syndrome. Downs Syndr Res Pract. 2006 Jul;10(1):10-22. doi: 10.3104/reports.301. Citation on PubMed

Lott IT, Head E. Alzheimer disease and Down syndrome: factors in pathogenesis. Neurobiol Aging. 2005 Mar;26(3):383-9. doi: 10.1016/j.neurobiolaging.2004.08.005. Citation on PubMed

Lubec G, Engidawork E. The brain in Down syndrome (TRISOMY 21). J Neurol. 2002 Oct;249(10):1347-56. doi: 10.1007/s00415-002-0799-9. Citation on PubMed

Roizen NJ, Patterson D. Down's syndrome. Lancet. 2003 Apr 12;361(9365):1281-9. doi: 10.1016/S0140-6736(03)12987-X. Citation on PubMed

Shapiro BL. Down syndrome and associated congenital malformations. J Neural Transm Suppl. 2003;(67):207-14. doi: 10.1007/978-3-7091-6721-2_18. Citation on PubMed

Sherman SL, Allen EG, Bean LH, Freeman SB. Epidemiology of Down syndrome. Ment Retard Dev Disabil Res Rev. 2007;13(3):221-7. doi: 10.1002/mrdd.20157. Citation on PubMed

Steingass KJ, Chicoine B, McGuire D, Roizen NJ. Developmental disabilities grown up: Down syndrome. J Dev Behav Pediatr. 2011 Sep;32(7):548-58. doi: 10.1097/DBP.0b013e31822182e0. No abstract available. Citation on PubMed

Zigman WB, Lott IT. Alzheimer's disease in Down syndrome: neurobiology and risk. Ment Retard Dev Disabil Res Rev. 2007;13(3):237-46. doi: 10.1002/mrdd.20163. Citation on PubMed

MedlinePlus links to health information from the National Institutes of Health and other federal government agencies. MedlinePlus also links to health information from non-government Web sites. See our disclaimer about external links and our quality guidelines.

The information on this site should not be used as a substitute for professional medical care or advice. Contact a health care provider if you have questions about your health.

# data[].attributes.attachment_link.description
To use the sharing features on this page, please enable JavaScript. Down syndrome is a chromosomal condition that is associated with intellectual disability, a characteristic facial appearance, and weak muscle tone (hypotonia) in infancy. All affected individuals experience cognitive delays, but the intellectual disability is usually mild to moderate.

# data[].attributes.headline
A picture of the chromosome carrying the gene of the disorder

# data[].attributes.subject
A picture of the chromosome carrying the gene of the disorder

# data[].attributes.headline
Picture of Inheritance of Down’s Syndrome 

# data[].attributes.subject
Picture of Inheritance of Down’s Syndrome 