About Down Syndrome

The National Down Syndrome Congress has created an online guide to assist physicians facing the challenge of informing parents that a child has or may have Down syndrome. To view this invaluable guide, click here.

The most common form of Down syndrome is known as Trisomy 21. Individuals with Trisomy 21 have 47 chromosomes instead of the usual 46 in each of their cells. Down syndrome is a common genetic variation which usually causes delay in physical, intellectual and language development.

The exact causes of the chromosomal rearrangement and primary prevention of Down syndrome are currently unknown.

Down syndrome is one of the leading clinical causes of cognitive delay in the world – it is not related to race, nationality, religion or socio-economic status.

The incidence of Down syndrome in the United States is estimated to be 1 in every 733 live births.

Of all children born in this country annually, approximately 5,000 will have Down syndrome.

There are approximately 1/4 million families in the United States affected by Down syndrome.

The likelihood of giving birth to a child with Down syndrome increases with maternal age; nevertheless, 80% of babies with Down syndrome are born to women under 35 years of age, as women in that age group give birth to more babies overall.

There is wide variation in mental abilities, behavior and physical development in individuals with Down syndrome. Each individual has his/her own unique personality, capabilities and talents.

30% – 50% of the individuals with Down syndrome have heart defects and 8% – 12% have gastrointestinal tract abnormalities present at birth. Most of these defects are now correctable by surgery.

Individuals with Down syndrome benefit from loving homes, early intervention, inclusive education, appropriate medical care and positive public attitudes.

In adulthood, many persons with Down syndrome hold jobs, live independently and enjoy recreational opportunities in their communities.