Mosaic Down syndrome is a variant of Down syndrome. Down syndrome is a congenital (present at birth) genetic condition that occurs when a person has three copies of chromosome 21 instead of two ...

Emma McLean is a 6-year-old girl who loves Taylor Swift, reading books, playing the drums and hanging with her little sister. While Emma has Down syndrome — specifically a rare type called ...

A century after Down syndrome was first described, scientists discovered that the root cause of this disorder is a condition called trisomy 21. What strides in research have been made since then?