Are One in 200 Genes Dispensable?
A new study suggests we can carry many messed up genes without obvious consequence.
New research adds to growing evidence that the average human genome can harbor
many mistakes without serious harm. The study, published today in the American
Journal of Human Genetics, looked at genetic variations in 1000 people around
the world.
According to a press
release from the Wellcome
Trust Sanger Institute:
[The researchers] focused their work on single-letter changes (called SNPs) that disrupt
proteins, leading to versions that are either shorter or completely absent. One
might intuitively expect that such a change – called a nonsense-SNP – would be
harmful to the person.
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“We knew that these mutations existed and that many have been
associated with genetic diseases, but we were amazed to find that they were so
common in the general population,” said Bryndis Yngvadottir, lead author
on the study. “We found that 167 genes could be inactivated by nonsense
mutations, and that individuals carry on average at least 46 such variations.
For 99 of the genes, both copies could be lost in adults living a normal
existence.”
Human DNA contains approximately 20,000 genes: the total of 99 genes with
nonsense-SNPs means that at least 1 in 200 genes is dispensable. Some harmful
nonsense-SNPs were also present among the 167 genes studied: 8 are listed in
the Human Gene Mutation Database, which catalogues disease-causing mutations.
…”Certain types of genes tend to be lost preferentially. We found the
biggest decrease in the genes that contribute to our sense of smell.
Perhaps early humans didn’t like smelly partners, and so when humans
started to live together in big groups it helped their chances of
finding true love if they couldn’t smell their partner too strongly,”
speculated Bryndis Yngvadottir.
