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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.
Life expectancy among adults with Down syndrome is about 55 years, though average life span varies. The name Down syndrome comes from the physician, Dr. Langdon Down, who first described the collection of findings in 1866. It was not until 1959 that the cause of Down syndrome (the presence of an extra #21 chromosome) was identified.