Additional file 1: Figure S1. of The landscape of sex-differential transcriptome and its consequent selection in human adults

Differential expression score. Landscape of scores for all possible ratios of men and women expression values using a base 2 logarithm. The formula we derived for SDE score can be generalized to compare the difference between two populations (x and y) in a certain tissue or condition (t), normalizing by a gene (g) maximal expression value (MAXg). This differential expression score (DES) is a logarithm of the normalized ratios, giving scores between −1 and 1. We use a logarithm base of 2, but other bases (n) are possible. The general expression is thus DES = LOGn{(1 + (EXPR g, t x /MAXg) * (n − 1))/(1 + (EXPR g, t y /MAXg) * (n − 1))} where EXPR g, t x is the expression value of gene g in tissue/condition t for population x. This score returns the differential expression value of a gene in specific tissue/condition, relative to the maximal expression of the gene. The value ranges from 1 (exclusive expression in x) to −1 (exclusive expression in y). Larger logarithm bases (n) exponentially increase the transitions between exclusive expression (1 and −1) and non-differential (0) scores. (PDF 276 kb)