Interesting (if not useful) genetics

Stuff has a story on a new genetic finding:  the cause of (naturally) blond hair in Melanesians, which turns out to be different from the cause in Europeans. You can read the full paper at Science (annoying free registration)

The researchers looked at DNA samples from 43 blond and 42 dark-haired Solomon Islanders. First, they looked at a grid of DNA markers that are relatively easy and cheap to measure.  This pointed out a region of the genome that differed between the blond and dark-haired groups.  The region contained just one gene, so they were then able to determine the complete genetic sequence of the gene in 12 people from each group.  This led to a single genetic change that was a plausible candidate for causing the difference, which the team then measured in all 85 study participants, confirming that it did determine hair color.

The result is interesting, but not all that useful. The gene responsible was already known to be involved in hair and skin color, in humans and in other animals, so that didn’t provide anything new, and if you want to find out or change someone’s hair colour, there are easier ways.  Still, it’s interesting that blond hair has appeared (at least) twice — most traits with multiple independent origins are more obviously useful, like being able to digest milk as an adult, or being immune to malaria.

This general approach of a wide scan of markers and then follow-up sequencing is being used by other groups, including a consortium I’m involved in.  Although it worked well for the hair-color gene, it’s a bit more difficult to get clear results for less dramatic differences in things like blood pressure. Fortunately, we have larger sample sizes to work with, so there’s some chance.   We’re hoping that finding the specific genetic mechanisms behind some of the differences will provide leverage for opening up more understanding of how heart disease and aging work.  If we’re lucky.