Tuesday, May 25, 2010

Term Tuesday: SNP

Wow.  This little blog has 2 followers.  That's more followers than there are posts.  Crazy.  OK, well, not to disappoint my fans, I will renew my effort to explore the world of biological science, particularly genetics with you.

So... introducing Term Tuesday, where I'll pick some cool term at random and try to shed light on what it means.

Today's term is SNP.  Most people pronounce it "snip".  It stands for  Single Nucleotide Polymorphism.  Kind of a mouthful, no?  Maybe, but it's pretty simple. While most of our genes are made up of the same combination of the nucleotides A, G, C, and T, from time to time there will be one "letter" different.  A single nucleotide. And this small difference is not enough to change the resulting protein product, or whatever that piece of DNA encodes.  It's just enough to be a variation, or polymorphism. Like a different way of spelling the same word.

So why do people care about SNPs?  Turns out they can be very useful.  One example of how they are cool is that SNPs can be used to identify candidate disease genes.  Since everyone carries around a different combination of SNPs, geneticists can compare SNPs in people with a disorder to people without a disorder.  If enough SNPs associate with a disease, there's a good chance a gene associated with the disease is located on the DNA near the SNP.  So SNPs can act as a road mile marker.  They're so useful in fact that researchers have identified common SNPs in the population and put them all on a gene chip, to make the identification process go that much faster.  Once a set of SNPs have been identified, a small chip containing disease-related SNPs can be made, to quickly and economically assess someone's risk for carrying a yet-to-be-identified disease gene or genes.  Neat, huh?

I bet there's lots more about SNPs but that's all I have time for today.   Any driving questions?  Just post a comment!


  1. Very interesting! What exactly is a gene chip??

  2. awesome - this is what we work on! fyi - i am a friend of caroline's from the south. working on a population-based breast cancer cohort. and we will be snippin and chippin dna soon :)

  3. Sweeeet.

    Alina, I'll cover gene chips another day. I'm realllly far behind on this project, and since someone is actually reading this, it's super motivating.