Costanzo, M. et al. Science 353, aaf1420 (2016).

The synthetic genetic array approach is used to identify genetic interactions in the yeast Saccharomyces cerevisiae. In this method, double mutants are constructed and evaluated for fitness. If fitness is greater than expected, the genetic interaction is classified as positive; if fitness is poorer than expected, the genetic interaction is classified as negative (often the two genes code for proteins in the same complex or process). Costanzo et al. now present a global genetic interaction network for yeast, covering nearly all ∼6,000 yeast genes. By constructing more than 23 million double mutants, they identified ∼350,000 positive and ∼550,000 negative pairwise genetic interactions. This ultra-dense map, illustrating the functional architecture of the yeast cell, should serve as an important resource for studying the relationships between genes, and it may also be useful for drug discovery.