(CNN) — Here’s a look at Down syndrome, a genetic condition that affects cognitive ability, causing mild to severe learning disabilities and distinctive facial features.
There are three types of Down syndrome: translocation, mosaicism, and trisomy 21. Trisomy 21 is the most common, contributing to 95% of cases.
Facts
The English physician John Langdon Down characterized it for the first time in 1866.
It is a condition or syndrome, not a disease.
It is due to extra material on chromosome 21. In those with trisomy 21, the individual possesses a complete extra copy of the chromosome.
There is currently no prevention, and treatment includes early intervention, speech, occupational, emotional, and other therapies, supplements, medications, and assistive devices.
Risk factors that can lead to the conception of a child with Down syndrome include advanced maternal age or a father with Down syndrome. A couple who already have a child with Down syndrome have a one percent chance of conceiving another.
The condition can be diagnosed through various prenatal screening tests.
Physical characteristics: short stature, decreased muscle tone, irregularly shaped ears, flat face, upturned eyes, a deep crease in the palms of the hands, the ability to extend the joints beyond the usual range, a large space between the big toe and next toe, and a large tongue relative to the size of the mouth.
Health: People with Down syndrome may also have, or are at risk for, heart defects, vision and/or hearing problems, thyroid conditions, obesity, gastrointestinal conditions, memory loss, seizures, and some types of cancer.
Down Syndrome Statistics
In the United States, about 6,000 children are born with this syndrome each year.
In 2008, an estimated 250,000 people in the United States had this syndrome.
The average life expectancy is about 60 years.
Language tips from the National Down Syndrome Society
“A child/adult with Down syndrome” is the preferred reference, as opposed to “he/she has Down” or “suffers” Down syndrome.
