Ultraconserved elements investigated

One of the surprises when the numerous whole genomes started to come out, was that they contain short regions that are extremely conserved. They were named ultra-conserved elements and were defined to be at least 200 bp and almost perfectly conserved. These elements were found in species as far apart as human and mouse. Usually, such conservation hints about important function. Notice that this conservation is much stronger than what we usually see in genes, and therefor it was expected that we would find a new exciting mechanism using these regions.

However, a recent publication (Ahituv et al, PLoS Biology) details how knockouts of these regions in mouse gave no hints about functionality. In fact, the mice were as viable as any other mouse. This does not rule out that the regions are important and functional, but the extreme conservation does no longer imply extreme importance.