Fig. 2.

Topological structure and score of gene pair. For a pair of genes (X, Y), node P represents the measured quantitative phenotype. Dotted line means that the connection may be not a direct edge in the pathway network. Based on Gaussian distribution, the score for each topological structure is defined by the probability of actual double mutation measured phenotype value (fitness). Where, D(x, y) is (x, y) double mutant fitness, S(.) is single mutant fitness, and E(x, y) is typical genetic interaction value defined as [22]. The variance σ ² is the empirical variance of repeated experiments, and p is the prior probability for each given topological structure