An Overview of Down Syndrome

Down syndrome is the most commonly occurring chromosomal condition. Approximately one in every 700 babies in the United States is born with Down syndrome, that is about 6,000 each year. Down syndrome is a genetic condition that occurs in people of all races and socioeconomics levels. The incidence of births of children with Down syndrome increases with the age of the mother. But due to higher fertility rates in younger women, 80% of children with Down syndrome are born to women under 35 years of age (ndss, 2017).

Down syndrome can result from three types of chromosomal abnormalities.

Trisomy 21 increases the risk for premature aging and certain medical conditions such as congenital heart defects, respiratory and hearing problems, Alzheimer's disease, childhood leukemia and thyroid conditions. Many of these conditions are now treatable, so most people with Down syndrome lead healthy lives, with a life expectancy of approximately 60 years (ndss, 2017).

Adults with Down syndrome almost always have some degree of cognitive delay, but it is usually in the mild (IQ of 50-70) to moderate (IQ of 35-50) range and ocassionally severe (IQ of 20-35), (Bull, 2011). There is a wide variation in the communicative and cognitive status of adults with Down syndrome. Some speak clearly and understandably, others have significant issues with grammar and articulation, and a small number depend on augmentative communication devices. Many adults with Down syndrome attain functional levels for reading, writing, and math; others have been less successful in these areas. While there is usually some degree of impairment in both fine and gross motor skills, many adults with Down syndrome are good athletes and hold responsible jobs.

Adults with Down syndrome tend to have common physical characteristics, including:

To learn more, consider visiting the National Down Syndrome Society web page
What is Down Syndrome?

Adults with Down syndrome often have certain medical conditions.



Bull, M. (2011). Health Supervision for Children With Down Syndrome. Pediatrics. 2011, 128 (2), 393-406

National Down Syndrome Society. Down Syndrome Fact Sheet. retrieved online 09/15/17