Template:Trisomy 21 Vignette
From Embryology
| Historic Embryology |
| John Langdon Haydon Down (1828-1896) in 1866 first clinically identified the phenotype in patients, that then became known as "Down Syndrome". It was not until the next century with the development of genetic analysis that the Trisomy 21 basis of this developmental abnormality was identified. |