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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.
Confidence votes 994. John Glenn (born July 18, 1921, in Cambridge, Ohio), a decorated US Marine Corps pilot, flew the first US orbital mission, completing three orbits of the Earth in his space capsule, Friendship 7 , on February 20, 1962. He was the third American in space, following sub-orbital flights by Alan Shepard and Virgil Gus Grissom.