Resurrected gene springs back to life
20 Mar 2009 by Evoluted New Media
A gene with links to Crohn’s disease has an unusual evolutionary history, according to researchers into human genetics at the University of Washington in Seattle.
A gene with links to Crohn’s disease has an unusual evolutionary history, according to researchers into human genetics at the University of Washington in Seattle.
The gene that codes for Immunity-related GTPase M (IRGM) is found in most mammals and is a member of a large family of related genes that help eliminate pathogens. In humans and primates, this gene has been lost over time, Evidence from ancestral DNA would indicate that a short fragment of repeated DNA found throughout the human genome inserted itself into the gene of a common ancestor of Old and New World monkeys about 40 million years ago.
This insertion inactivated IRGM and a functioning protein was not longer viable. Then some 20 million years later, a retrovirus in the ancestors of humans and apes inserted into the IRGM gene that once again allowed the gene to produce a protein.
Speaking from the University of Washington, Evan Eichler said: “This is like lightening striking twice in the same spot” and is probably the first example of a resurrected gene. He adds “the only way to be sure a gene won’t come back is delete it”.
The importance of IRGM in humans today is sketchy, but a deletion in front of the gene has been linked to an increased risk in Crohn’s disease, an autoimmune disease of the lower digestive system.
Whereas this is currently the only example of a gene known to have been killed and then brought back to life, only future studies of comparative genomic data will show whether this is something of general importance or a fluke example that we only see once.
By Georgina Lavender
