With the newest DNA sequencing technology starting to reach the market, we're seeing a bit of a bifurcation. Some of the methods can do long reads, covering hundreds of bases, and provide data that's appropriate for assembling a genome that's never been sequenced before. Others produce lots of shorter reads, which can only be aligned to a genome that we know the sequence of already. What good is repeating a completed genome? Potentially quite a lot, if that genome happens to be human and, more particularly, yours, since it can provide information on medically relevant issues like disease risks and drug efficacy. The goal here is to make this so cheap that sequencing a person's genome could be routine.

A big step in that direction may have been taken by a company called Complete Genomics, which describes the methods it used to sequence three human genomes in a paper that will be released by Science today. The system described in the paper combines some clever variants of well known molecular biology techniques to read massive amounts of DNA fragments that are, in total, about 65 bases long. But, because the materials used for the reactions are so common, even the enzymes can be purchased cheaply. That allows Complete Genomics to bring an entire human genome in while spending less than $5,000 on materials. All that, plus an error rate of less than one base in 100,000.

For comparison, the completion of Jim Watson's genome, done just a few years ago, is estimated to have cost $20 million.