Fu, Y. et al. Proc. Natl. Acad. Sci. USA 112, 11923–11928 (2015).

Recovering a genome sequence from the tiny quantity of DNA in a single cell requires considerable amplification, which leads to strong biases. Multiple-displacement amplification (MDA) is a method chosen often for its robust amplification, but many sequences are amplified either preferentially or not at all, skewing genetic interpretation. Fu et al. have designed a simple way around uneven amplification that involves isolating single-cell DNA fragments into individual oil droplets and using each droplet as a separate reaction chamber. Amplifying in an emulsion allows each genomic region to reach saturation regardless of amplification kinetics. The authors show that emulsion whole-genome amplification (eWGA) provides sensitive detection of copy-number variation and single-nucleotide polymorphisms in single human cells. The approach works with commercial emulsion generators.