Down syndrome has been around for many centuries but was misinterpreted as a mental disability. Many of the children born with Down syndrome were sent to convents and referred to as "children of God." It wasn't until the 19th century that this genetic disorder began to be understood. English physician John Langdon Down, who entered medical school on this date in 1853, would later give his name to the syndrome he first documented. In his 1866 paper "Observations on an Ethnic Classification of Idiots," Down described the physical characteristics of the syndrome. In the 1930s, doctors began realizing that Down syndrome might be caused by a chromosomal abnormality. French geneticist Jerome Lejeune finally discovered the chromosomal error in 1959, noting that people with Down syndrome have extra genetic material in the 21st chromosome.

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