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?

There are three partial trisomy mouse models of human trisomy 21, all trisomic for a portion of MMU 16. The gene content of these partial trisomies is shown on the right.

Trisomy 18, also known as Edwards syndrome ... or only a section of the extra chromosome 18 present in their cells (Partial Edwards syndrome). A fetus with Partial Edwards syndrome may be ...