PCA plot of cross-correlations between chloroquine-induced and histamine-induced itch assays (CHLITCH, HISTITCH) and assays of thermal nociception (HP, HT, TF, TW47.5, TW49) spontaneous inflammatory nociception (ACAA, AAMS, BV, CAP, FEarly, FLate) in otherwise naïve mice, mechanical sensitivity (VF) and mechanical hypersensitivity (DYNVF, PACVF, PNIVF, SNIVF). Both CHLITCH and HISTITCH are negatively correlated with assays of spontaneous inflammatory nociception. CHLITCH, but not HISTITCH, exhibits strong positive correlations with mechanical sensitivity and mechanical hypersensitivity assays (except SNIVF), indicating that common genetic mechanisms contribute to these assays and itch induced by chloroquine. CHLITCH, but not HISTITCH, is also negatively correlated with assays of thermal nociception, indicating shared genetic mechanisms with opposite effects. The proportion of total variance accounted for is 0.63. Font color reference is as in Fig. 2 legend.