Jerome Lejeune

The group of birth characterisitics we refer to as Down syndrome was named after the man who first observed these traits, John Langdon Down.

For over half a century parents who had given birth to "mongol" children fell under the suspicion of breeding racial degeneracy and their offfspring were segregated in institutions and denied treatment or education.

Fast forward to 1950, and entering the research scene was scientist Jerome Lejeune, now widely regarded at the father of genetics. 

Already some scientists speculated that Down's was caused by a fault in the chromosomes. Following this lead and using the new technique of karyotyping he discovered, in 1958, that a patient with Down's had an extra chromosome at the 21st pair. The genetic diagnosis known as Trisomy 21 was born, establishing the first ever link between mental disability and a chromosome disorder, heralding a new era in genetics and marking a new beginning for people with the condition and their families.

Read more about this incredible innovator on http://www.mercatornet.com/articles/saintly_scientists_hate_the_disease_love_the_diseased/