Saturday, September 22, 2007

Hypotheses from the New Yorker?   posted by p-ter @ 9/22/2007 12:06:00 PM

In the middle of an otherwise boring New Yorker article about where to buy coats for the coming winter, I came across this passage, describing the author's (possibly tongue-in-cheek) search to understand why she seems to feel cold more acutely than other people:
I called Dr. Andrej Romanovsky... to ask how the body detects cold. According to Romanovsky, the going theory is that a newly discovered receptor (TRPM8, if you were wondering [I was!]) reacts to low temperatures. This same molecule also reacts to menthol, which accounts for the compound's cool feel on the skin. So why is it that certain people whine more than others when the temperature drops? "I don't think anybody studies what you want them to study, " Romanovsky told me.
Not true, Dr. Romanovsky! Sometimes people study exactly what you want them to study. I googled my way to this study, entitled "Genetic predictors for acute experimental cold and heat pain sensitivity in humans":
Background: The genetic contribution to pain sensitivity underlies a complex composite of parallel pain pathways, multiple mechanisms, and diverse inter-individual pain experiences and expectations.

Methods: Variations for genes encoding receptors related to cold and heat sensation, such as transient receptor potential A subtype 1 (TRPA1), M subtype 8 (TRPM8), V subtype 1 (TRPV1), {delta} opioid receptor subtype 1 (OPRD1), catechol O-methyltransferase (COMT), and fatty acid amide hydrolyase (FAAH), were investigated in four major ethnic populations.

Results: We defined 13 haplotype blocks in European Americans, seven blocks in African Americans, seven blocks in Hispanic subjects, and 11 blocks in Asian Americans. Further study in European American subjects found significant associations between short duration cold pain sensitivity and variations in TRPA1, COMT, and FAAH in a gender dependent manner. Our observations demonstrate that genetic variations in TRPA1, COMT, and FAAH contribute gender specifically to individual variations in short duration cold pain sensitivity in a European American cohort.

Conclusions: The effects of TRPA1 variations on experimental short duration heat pain sensitivity may contribute to inter-individual variation in pain sensitivity in humans.
Ok, these associations are highly questionable (anyone want to fund a large genome-wide association study of cold tolerance to put the question to rest?), but still, there are scientists asking these sorts of questions.

I also checked out a couple of the genes in Haplotter-- selection for cold tolerance was likely very strong as humans moved north out of Africa. There are some perplexing signals-- TRPM8 shows some evidence for selection, but in the Yoruba (Nigeria: probably not exerting a selection pressure for increased cold tolerance). TRPV1 (a receptor involved in heat tolerance) shows a huge signal in the Yoruba as well; this makes more sense.

Nothing too exciting, I just was amused that my furious googling was inspired by an article about coats in the "style issue" of the New Yorker. And contrary to Dr. Romanovsky's claim, understanding why people feel cold differently is very much an active area of research (and well within the reach of current technology).

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