Multiplying DNA One Drop at a Time

RainDance Technologies says its method of amplifying DNA in drops of water will expand clinical genetic testing.

As the cost of DNA sequencing continues to fall and scientists discover a growing number of genes linked to different diseases, the field of genetic diagnostics is preparing for a boom. Rather than the single-gene tests common today, clinical genetics laboratories are developing tests that simultaneously detect tens or even hundreds of genetic mutations linked to cancer and other diseases, as well as conditions such as mental retardation.
However, with these more complex tests, diagnostic developers need to be able efficiently and accurately select specific portions of the genome for analysis. "Now the cost of sequencing is so cheap you don't have to look at just one or two genes, you can look much more broadly," says Alexis Borisy, entrepreneur in residence at Third Rock Ventures and acting chief executive of Foundation Medicine, a Cambridge, MA-based startup developing genetic tests for analyzing cancer. "But the whole genome or exome [the portion of the genome that codes for proteins] is still too expensive to be clinically useful, so you have to focus the search."
RainDance, a startup based in Lexington, MA, aims to fill that gap with its droplet-based microfluidics technology. Founded in 2004, the company uses picoliter-sized droplets as tiny test tubes to carry out chemical reactions at very small volumes. Precisely sized droplets are created on a microfluidics chip by surrounding aqueous liquid with small volumes of oil. The droplets, generated at a rate of 10 million per hour, can be tightly packed and injected with different reagents, including strands of DNA. To catalyze a reaction, an electrical signal triggers droplets containing different reagents to merge.