Down syndrome

The story

Named after English physician John Langdon Haydon Down (1828–1896), who first described the condition as a distinct form of mental disability in the 1860s.

First known use, by meaning

• from 1961. A genetic disorder caused by the presence of all or part of a third copy of chromosome 21 (a chromosomal excess), whereby the patients typically have a delay in cognitive ability and physical growth, as well as a small head and tilted eyelids.