Down syndrome was not discovered by a man of the name Down, despite popular belief. It was discovered by Jérôme Lejeune and Dr. Raymond Turpin. As Lejeune and Turpin studied the hands of children with Down syndrome, they found that the reason for their strange fingerprints appeared during embryo formation. After conducting more experiments, Dr. Lejeune found that the strange skin was the result of a chromosomal accident.

How was Down syndrome discovered?