What is it ? Down syndrome, also called Trisomy 21, is a genetic condition in which extra genetic material causes delays in physical and intellectual development. It occurs in 1 in every 1000 live births, and the physical features and medical problems associated can differ widely from child to child.
Individuals with Down syndrome have 47 chromosomes instead of the usual 46, and although Down syndrome can't be prevented, it can be detected before a child is born. Down syndrome is the most frequently occurring chromosomal disorder and the most important fact to known about individuals with Down syndrome is that they are a lot like us.