Bejerano G, Pheasant M, Makunin I, Stephen S, Kent WJ, Mattick JS, Haussler D.

Science. 2004 May 28;304(5675):1321-5

Ultraconserved elements in the human genome

Ultraconserved elements are stretches > 200 bp 100 % conserved from mouse to human. One can sort them in three classes exonic, non-exonic, unknown. Non exonic are preferentially found around devlopmental genes and transcription factors.