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Down Syndrome Facts

Down syndrome is a chromosomal variation which usually causes delays in physical, intellectual and language development.


Down syndrome is one of the leading causes of mental retardation – it is not related to race, nationality, religion or socioeconomic status.


The incidence of Down syndrome in the United States is estimated to be 1 in every 722 live births (about 4,000 individuals each year) affecting approximately 250,000 families.


The exact cause and prevention of Down syndrome are currently unknown.


While the likelihood of giving birth to a child with Down syndrome increases with maternal age, 80 percent 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 are three types of Down syndrome. 88–90% of individuals received an extra chromosome, from one parent or the other at conception.The other two forms, which are quite rare, are called Mosaic and Translocation. About 4–5% of individuals with Down syndrome have translocation trisomy-21. Translocation occurs when a piece of a chromosome or a whole chromosome breaks off during cell division and attaches itself to another chromosome. About 1% of individuals with Down syndrome have mosaic Down syndrome – this means that different cells within an individual have different chromosomal makeup. In Down syndrome mosaicism, the individual has some cells with the typical number of chromosomes (46) and some cells with an extra chromosome 21, for a total of 47 chromosomes. 

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


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


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


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


from National Down Syndrome Society

© 2016 by Down Syndrome Association of North Central Iowa. Proudly made by

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