Study finds one percent of human genes switched off

Fri Feb 17, 2012 9:44am EST
 
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By Kate Kelland

LONDON (Reuters) - Scientists studying the human genome have found that each of us is carrying around 20 genes that have been completely inactivated, suggesting that not all switched-off genes are harmful to health.

A team at Britain's Wellcome Trust Sanger Institute is developing a new catalogue of so-called "loss-of-function" (LoF) gene variants to help identify new disease-causing mutations, and say their work will help scientists better understand the normal function of human genes.

Working as part of larger study called the 1000 Genomes Project, the team developed a series of filters to identify common errors in the human genome, which maps the entire genetic code.

"The key questions we focused on for this study were how many of these LoF variants were real and how large a role might they play in human disease," said Daniel MacArthur of the Sanger Institute, who worked on the team.

The researchers looked at nearly 3,000 possible LoF variants in the genomes of 185 people from Europe, East Asia and West Africa. Their findings were published in the journal Science on Thursday.

Loss of function variants are genetic changes that are predicted to severely disrupt the function of genes. Some are known to cause severe human diseases such as muscular dystrophy and cystic fibrosis.

Previous genome sequencing projects have suggested there are hundreds of these variants in the DNA of even perfectly healthy individuals, but researchers were not able to tell exactly how many.

In this study, the filters revealed that 56 percent of the 3,000 possible LoFs analyzed were unlikely to seriously affect gene function.   Continued...