IN THE DECADE since researchers first sequenced the human genome, obvious links between the genes and individual diseases have been slow to appear [see “Revolution Postponed,” by Stephen S. Hall; Scientific American, October]. Many researchers now believe that real advances in genomics will come not from simple X-causes-Y correlations but from a rich statistical understanding that emerges out of the sequences of millions of genomes—a set that reveals how our genetic code is likely to interact with the environment to make us who we are.
This, in turn, requires a cheap genome sequencer, something that can do the job for less than $1,000. Right now it costs between $5,000 and $15,000 to sequence a genome—a great improvement from the $2.7 billion it originally cost but still far from the goal. Researchers at IBM and Roche are trying to get there by undertaking a radical redesign of gene-sequencing machines. Whereas existing dishwasher-size sequencers require expensive chemical reagents to analyze genes that have been sliced into thousands of small fragments, the so-called DNA transistor takes an almost naively simple approach. In it, an intact DNA molecule threads through a three-nanometer-wide gap in the middle of a silicon chip. As the DNA feeds through the nanopore, an electrical sensor reads it one molecular unit, or base, at a time.