Interesting Facts about Down Syndrome

Down syndrome is the only trisomy compatible with life. The other two known trisomies leave a baby with only a 5% chance of surviving. In 90% of trisomy 21 cases, the extra chromosome comes from the mother's egg rather than the father's sperm. The cause of down syndrome was discovered in 1959 by Jerome Lejeune. It affects 1 out of every 800 babies.