Down Syndrome


A condition categorized by having an extra copy of chromosome 21, which can cause various intellectual and physical changes.


Down syndrome is also called Trisomy 21, with trisomy being the term for having an extra chromosome and 21 referring to the specific duplicated chromosome.

The CDC says that people with Down syndrome usually have mildly-to-moderately-low intelligence and commonly can have physical traits including a flattened face, almond-shaped eyes, a shorter neck, smaller ears, a tongue that might stick out of the mouth, smaller hands and feet, and shorter height.

Prevalence is roughly 1 in 700 babies in the United States.