Genes from nowhere: Orphans with a surprising story
16 January 2013 by Helen Pilcher
NOT having any family is tough. Often unappreciated and uncomfortably different, orphans have to fight to fit in and battle against the odds to realise their potential. Those who succeed, from Aristotle to Steve Jobs, sometimes change the world.
Who would have thought that our DNA plays host to a similar cast of foundlings? When biologists began sequencing genomes, they discovered that up to a third of genes in each species seemed to have no parents or family of any kind. Nevertheless, some of these “orphan genes” are high achievers, and a few even seem have played a part in the evolution of the human brain.
But where do they come from? With no obvious ancestry, it was as if these genes had appeared from nowhere, but that couldn’t be true. Everyone assumed that as we learned more, we would discover what had happened to their families. ..
Some other researchers, however, are starting to think it may be surprisingly common. A study of 270 primate orphan genes, led by M. Mar Albà and Macarena Toll-Riera of the Municipal Foundation Institute for Medical Research in Barcelona, Spain, found that only a quarter could be explained by rapid evolution after duplication (Molecular Biology and Evolution, vol 26, p 603). Instead, around 60 per cent appeared to be new. “De novo evolution is clearly a strong force – constantly generating new genes over time,” says Tautz. “It seems possible that most orphan genes have evolved through de novo evolution.”
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