Wednesday, March 11, 2009

Dead Gene Comes Back To Life In Humans

FISH analysis of IRGM. The figure shows examples of FISH experiments on Hs (Homo sapiens), Rh (Macaca mulatta), Cja (Callithrix jacchus) and Lca (Lemur catta), with the use of human fosmid clone WIBR2-3607H18 (A, B, C) and lemur species-specific BAC clone LB2-77B23 (D). (Credit: Bekpen et al. Death and Resurrection of the Human IRGM Gene. PLoS Genet, 5(3): e1000403 DOI: 10.1371/journal.pgen.1000403)

From Science Daily:

ScienceDaily (Mar. 11, 2009) — Researchers have discovered that a long-defunct gene was resurrected during the course of human evolution. This is believed to be the first evidence of a doomed gene – infection-fighting human IRGM – making a comeback in the human/great ape lineage. The study, led by Evan Eichler's genome science laboratory at the University of Washington and the Howard Hughes Medical Institute, is published March 6 in the open-access journal PLoS Genetics.

The truncated IRGM gene is one of only two genes of its type remaining in humans. The genes are Immune-Related GTPases, a kind of gene that helps mammals resist germs like tuberculosis and salmonella that try to invade cells. Unlike humans, most other mammals have several genes of this type. Mice, for example, have 21 Immune-Related GTPases. Medical interest in this gene ignited recently, when scientists associated specific IRGM mutations with the risk of Crohn's disease, an inflammatory digestive disorder.

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