- The extra chromosome often causes some level of mental retardation and is the number one cause of human birth defects
- Down syndrome affects one out of every 660 births.
- Older couples are more likely to produce offspring with the condition.
- Down syndrome is typically the product of a mistake in cell division at the time of conception, resulting in an embryo with a third copy of the 21st chromosome, instead of the typical two copies.
- Down syndrome can be diagnosed before or after birth.
- Common symptoms in children include slowed movement, reduced fertility, difficulty with speech, hearing loss, smaller heads with flat faces, short stature.
Facts About Down Syndrome
An example of down syndrome is a baby born with an extra chromosome.
Origin of Down syndromeafter J. L. H. Down (1828-96), British physician
or Down's syndrome
Origin of Down syndromeAfter John Langdon Haydon Down (1828-1896), British physician
Known only as Down's syndrome in the UK.
Named after John L.H. Langdon-Down (1828-1896), an English physician who described it in the late 1800s. The term was first used in 1961.