where does the name down syndrome come from
Down syndrome Down syndrome is one of the most common chromosome abnormalities in humans.[7] It occurs in about one per 1000 babies born each year.[1] In 2015, Down syndrome was present in 5.4 million individuals and resulted in 27,000 deaths down from 43,000 deaths in 1990.[9][10][18] It is named after John Langdon Down, the British doctor who fully described the syndrome in 1866.[19] Some aspects of the condition were described earlier by Jean-Étienne Dominique Esquirol in 1838 and Édouard Séguin in 1844.[20] In 1957, the genetic cause of Down syndrome, an extra copy of chromosome 21, was discovered.[19]