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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.
exists and is an alternate of . 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.