Down Syndrome

Down Syndrome Summary
Down syndrome is a chromosomal disorder that results in the presence of an additional third chromosome 21, also referred to as trisomy 21. Most individuals with Down syndrome have widely recognizable physical characteristics. The severity of Down syndrome ranges from mild to severe. Diagnostic testing for Down syndrome include amniocentesis, chorionic villus sampling, and percutaneous umbilical cord sampling. The most common risk factor for Down syndrome is a woman's age.
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Down syndrome facts

  • Down syndrome is a genetic disorder and the most common cause of cognitive impairment.
  • Individuals with Down syndrome have characteristic physical features that are widely recognized.
  • Down syndrome is associated with heart defects, gastrointestinal conditions, and other health issues.
  • Individuals with Down syndrome are at a high risk for developing dementia and early-onset Alzheimer's disease.
  • The only well known risk factor for conceiving a child with Down syndrome is advanced maternal age.
  • Screening for and diagnosis of Down syndrome is possible before birth.
  • Due to improved medical treatment and social inclusion, the average life span of an individual with Down syndrome is now more than 55 years.
  • Individuals with Down syndrome often live very healthy and productive lives.

What is Down syndrome?

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Down syndrome (also called Trisomy 21) is a genetic disorder that occurs in approximately 1 of 830 live births. It is the leading cause of cognitive impairment. Down syndrome is associated with mild to moderate learning disabilities, developmental delays, characteristic facial features, and low muscle tone in early infancy. Many individuals with Down syndrome also have heart defects, leukemia, early-onset Alzheimer's disease, gastro-intestinal problems, and other health issues. The symptoms of Down syndrome range from mild to severe.

Life expectancy for individuals with Down syndrome has dramatically increased over the past few decades as medical care and social inclusion have improved. A person with Down syndrome in good health will on average live to age 55 or beyond.

Down syndrome is named after Dr. Langdon Down, who in 1866 first described the syndrome as a disorder. Although Down made some important observations about Down syndrome, he did not correctly identify what causes the disorder. It wasn't until 1959 that scientists discovered the genetic origin of Down syndrome.

Medically Reviewed by a Doctor on 1/4/2014

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Down Syndrome - Symptoms Question: Are you caring for someone with Down syndrome? What symptoms is he/she experiencing with Down syndrome?
Down Syndrome - Experience Question: Please describe your child's experience with an early intervention program for Down syndrome.
Down Syndrome - Coping and Management Question: In what ways does having a child with Down syndrome affect your life and family?
Down Syndrome - Maternal Age Question: Was maternal age an issue in conceiving a child with Down syndrome? Please share your story.

Down Syndrome Symptoms

Down syndrome is a genetic disorder that is caused by mistakes in cell division during development of the human egg, sperm, or embryo. Over 90% of Down syndrome individuals have three copies of chromosome 21 instead of the normal two in all of their body cells.