The death and resurrection of IRGM - the "Jesus gene"

More than 50 million years ago the IRGM was a gene that played a vital role in the immune system of most mammals. It was then destroyed by a chunk of DNA called Alu which lead to the death of IRGM as it made the original gene worthless. 25 million years after Alu had infected the IRGM, it was then revived by a virus that inserted itself into the gene, which now is useful in both humans and great apes. Bekpen started researching this gene because of Chrohn's disease. He found that its active in several tissues including the heart, brain, kidneys, and testicles. He also found that it might again play a role in the immune system, and there is good reason to believe that this gene is now able to produce a protein again.

http://scienceblogs.com/notrocketscience/2009/03/the_death_and_resurrection_of_irgm_-_the_jesus_gene.php