Common Questions About Down Syndrome

What is Down syndrome?

Down syndrome is a common chromosomal disorder. The Centers for Disease Control and Prevention state that roughly 1 in 700 babies born in the United States are born with Down syndrome.

The human body is made up of trillions of cells, and within each cell is a nucleus that stores genetic material. This genetic information is contained in thread-like structures called chromosomes.

The nucleus of a typical human cell carries 23 pairs of chromosomes. Sometimes people are born with cells containing a full or partial copy of chromosome 21. The extra genetic material from this 21st chromosome causes Down syndrome.

What causes Down syndrome?

The exact cause of Down syndrome is unknown. Research shows that maternal age increases risk, however. The incidence of Down syndrome increases as the mother gets older. Women who are 35 and older when they become pregnant are more likely to have a pregnancy affected by Down syndrome.

Down syndrome is a genetic condition, but only 1% of Down syndrome cases are hereditary. 

Are there tests for Down syndrome?

There are screening and diagnostic prenatal tests as well as tests that can be done at birth.

Prenatal screening tests estimate the likelihood of the fetus having Down syndrome. Prenatal diagnostic tests, however, more accurately determine whether or not the fetus has Down syndrome.

Down syndrome can usually be identified at birth as it causes physical traits that are easily recognizable. A karyotype test examines the chromosomes in cells, and can confirm a diagnosis.

What are the symptoms of Down syndrome?

Down syndrome affects both mental and physical development. Typical characteristics associated with Down syndrome include low muscle tone, small stature, and eyes that slant upward. Down syndrome also causes cognitive delays that can range in severity.

A child born with Down syndrome may have no other major birth defects or medical issues, but Down syndrome is sometimes accompanied by other medical problems.

In 1960, the life expectancy of a person born with Down syndrome was around 10 years old. Today, however, 80% of adults with Down syndrome reach age 60. Down syndrome is a lifelong condition, but education and physical therapy services can help those born with Down syndrome reach their potential.