Skip to content

    Children's Health

    Select An Article

    Understanding Down Syndrome -- the Basics

    Font Size
    A
    A
    A

    What Is Down Syndrome?

    Down syndrome is one of the most common genetic birth defects. Usually, children born with the condition have some degree of mental retardation, as well as characteristic physical features. Many of these children also have other health problems.

    Each year in the U.S., approximately one in every 800 to 1,000 newborns has Down syndrome. This results in approximately 5,000 children born with Down syndrome each year.

    Understanding Down Syndrome

    Find out more about Down syndrome:

    Basics

    Symptoms

    Diagnosis and Treatment

    In the U.S. today, Down syndrome affects approximately 350,000 people. As many as 80% of adults with this condition reach age 55, and many live longer.

    The most common form of Down syndrome is often called "trisomy 21," because individuals with this condition have three copies of the 21st chromosome.

    What Causes Down Syndrome?

    Normally, each cell in the human body contains 23 pairs of chromosomes, which contain the genetic material that determines all our inherited characteristics. We receive half of each chromosome pair from our mother and the other half from our father. Individuals with the most common form of Down syndrome, trisomy 21, have an extra 21st chromosome.

    No one knows exactly why this chromosomal error occurs, but it does appear to be related to the age of the mother. At age 25, a woman has a one in 1,250 risk for having a child with Down syndrome. The risk increases to one in 952 at age 30, to one in 378 at age 35, to one in 106 at age 40 and one in 35 at age 45. However, 80% of children born with Down syndrome are born to mothers under the age of 35. This is because most babies, in general, are born to younger women.

    Be sure to check with your doctor if you are pregnant or plan to become pregnant if you have a family history of Down syndrome. There may be specialized tests to help you better understand your risk.

    WebMD Medical Reference

    Reviewed by Smitha Bhandari, MD on March 04, 2015
    Next Article:

    Today on WebMD

    child with red rash on cheeks
    What’s that rash?
    plate of fruit and veggies
    How healthy is your child’s diet?
     
    smiling baby
    Treating diarrhea, fever and more.
    Middle school band practice
    Understanding your child’s changing body.
     

    worried kid
    fitArticle
    jennifer aniston
    Slideshow
     
    Measles virus
    Article
    sick child
    Slideshow
     

    babyapp
    New
    Child with adhd
    Slideshow
     
    rl with friends
    fitSlideshow
    Child Coughing or Sneezing into Elbow
    Article