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It is named after John Langdon Down, the British doctor who fully described the syndrome in 1866. Some aspects of the condition were described earlier by Jean-Ãtienne Dominique Esquirol in 1838 and Ãdouard SÃ©guin in 1844. In 1957, the genetic cause of Down syndrome, an extra copy of chromosome 21, was discovered.
John Xantus (October 5, 1825 - December 13, 1894) Hungarian naturalist. Collected and named many previously unrecognized animals and plants in the southwestern U.S. and Mexico. John Xantus was born in 1825 of a well-to-do middle-class Hungarian family. During the revolution of 1848, he fought with the rebels against the Austro-Hungarian government and had to go into exile as a result. He fled by way of Amsterdam to England, and thereafter, in 1852, to the United States.