You Get What You Pay For

As we approach the 10th anniversary of the sequencing of the first human genome, the price of sequencing has gone down from a few million dollars to a few thousand. Researchers are talking about the advent of $1,000 genome as sequencing technology becomes faster and more efficient. But does cheaper mean better? Not necessarily, says The New Scientist's Michael Le Page. He says the advances in technological speed now mean that only short stretches of DNA can be sequenced at one time, "so the pieces have to be joined together by looking for overlaps between them." Early machines, though slower, sequenced pieces of DNA up to 900 bp long, Le Page says, while most next-gen technology can only manage 100 bp. More overlaps mean more possibilities for mistakes. "The next generation of sequencers should change this," he says. "The idea behind the leading contenders is to spy on the natural enzymes that replicate DNA by adding complementary bases to one strand of DNA. … Such machines should eventually be able to produce extremely long reads many thousands of base pairs long, greatly improving the quality of assembled genomes."