Thursday, November 11, 2010

Yawning over the latest news about the genes 'for' sleep

A story with headlines like "Gene for whether you sleep a lot or a little", "The Sandman gene", "How much you sleep is determined by genes", or "The gene for Zzzzzzzz" (that last one's on the Science site) would seem to promise news of a significant finding.  But it turns out that this is the report of a gene variant that may determine whether those who have it sleep 28 minutes less than those without it -- 7.5 vs 8 hours a night.  Wow!  What a difference.  It's rejuvenating just to think about it!

This was apparently a genomewide association study (GWAS, the genetic equivalent of snake oil, to some), of 4,200 Europeans, who had been asked how much they sleep.  As far as we can tell, the results have not yet been published. 

As Science reports,
Sleep duration correlated strongly with a single genetic marker in a gene called ABCC9. When allowed to sleep as long as they want, those who have two copies of one version of this marker sleep on average 6% less than those carrying two copies of the other version, or about 7.5 hours versus 8 hours, says postdoc Karla Allebrandt, who is leading the study at the Centre for Chronobiology headed by Till Roenneberg at the University of Munich in Germany. Allebrandt presented the work last week at the annual meeting of the American Society of Human Genetics in Washington, D.C.
ABCC9, or SUR2, is a gene that encodes an ATP-binding cassette transporter, or part of an ion channel that ferries potassium across cell membranes.
When the researchers knocked down the corresponding gene in two species of fruit flies, the flies slept significantly less at night compared with controls, Allebrandt reported.
Just how significant, we wonder.

Science also mentions, with no apparent irony, that sleep varies with weight -- people with a high body mass index tend to sleep less.  And therefore, the sentence following that one says, researchers are interested in sleep genes. But, this is a bit of a nonsequitur. Though, we hasten to add, on the part of the journalist, not, we assume, the researchers.  The story doesn't seem to be suggesting that the gene for sleep causes diabetes or heart disease, which are associated with obesity.  If it did, this connection might make sense, even if the suggestion did not.  But looking for genes for a trait that responds to largely non-genetic variables like weight?  No wonder the effect they report is so small.  Or should Leptin (a gene 'for' obesity) be renamed NoNap?

Reports like this are more sleep-inducing than any gene could be -- except when one thinks that research money was (predictably) thrown away on it

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