DS-Connect: The Down Syndrome Registry

National Institute of Child Health and Human Development (NICHD)

The registry provides an important resource to individuals with Down syndrome and their families.




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 grows during pregnancy, and how the person’s body functions after birth.


People with Down syndrome have an extra copy of one of these chromosomes, chromosome 21. This extra copy changes the body’s and brain’s development and can sometimes cause mental and physical problems for them, these can be facial appearance, and weak muscle tone (hypotonia). About half of all affected children are born with a heart defect.


Individuals with Down syndrome have an increased risk of developing several medical conditions; these include gastro esophageal reflux, which is a backflow of acidic stomach contents into the esophagus. About 15 percent have an underactive thyroid gland (hypothyroidism) organ in the lower neck that produces hormones. Individuals with Down syndrome also have an increased risk of hearing and vision problems. Small percentage of children with Down syndrome develops cancer of blood-forming cells (leukemia).


Small percentage also diagnosed with developmental conditions called Autism Spectrum disorders, which affect communication and social interaction.


Down syndrome remains the most common chromosomal condition diagnosed in the U.S, affecting 1 in every 700 babies born in the U.S. making Down Syndrome the most common genetic condition. Approximately 400,000 Americans have Down syndrome and about 6,000 babies with Down syndrome are born in the United States each year.


When Down syndrome was discovered


Down syndrome is named after John Langdon Down, the British physician who described the syndrome in 1866. Advances in medicine and science have enabled researchers to investigate the characteristics of people with Down syndrome. In 1959, the French physician Jerome Lejeune identified Down syndrome as a chromosomal condition. Instead of the usual 46 chromosomes present in each cell, Lejeune observed 47 in the cells of individuals with Down syndrome. It was later determined that an extra partial or whole copy of chromosome 21 results in the characteristics associated with Down syndrome.


Down syndrome occurs in people of all races and economic levels, though older women have an increased chance of having a child with Down syndrome. A 35 year old woman has about a one in 350 chance of conceiving a child with Down syndrome, and this chance increases gradually to 1 in 100 by age 40. At age 45 the incidence becomes approximately 1 in 30. The age of the mother does not seem to be linked to the risk of translocation.


How is Down syndrome diagnosed?


Most screening tests involve a blood test and an ultrasound; diagnostic tests can provide a definitive diagnosis with almost 100% accuracy. Advanced prenatal screens are now able to detect chromosomal material from the fetus that is circulating in the maternal blood.  These tests are not invasive but they provide a high accuracy rate. Still, all of these screens will not definitively diagnose Down syndrome. Prenatal screening and diagnostic tests are now routinely offered to women of all ages.


Although people with Down syndrome might have some physical and mental features in common, every person with Down syndrome is unique, and symptoms can range from mild to severe. People with Down syndrome often will benefit from special therapies that help to improve their physical and intellectual abilities. It is important to begin therapy services as early as possible.


• Many people with Down syndrome lead productive lives well into adulthood.


• Many individuals with Down syndrome are able to hold jobs and live independently.

However, it is important for people with Down syndrome to see a health care provider regularly throughout their lives.


• By law people with Down syndrome must be provided a free appropriate education through their public school system.


• People with Down syndrome participate in schools, workplace, religious groups, sport teams, volunteer organizations.


• Growing number of people with Down syndrome are choosing to get married and participating in post –secondary education programs.




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