Figure 4

Distribution of the PWD allele expression percentage in F1 progeny of AKR and PWD reciprocal crosses. The mouse X chromosome map is diagrammed in the middle of the figure. Each panel is a boxplot of an X-linked gene with its chromosomal position labeled. The red box is the distribution of the PWD allele expression percentage in P2 brains of 18 F1mice from the PWD X AKR cross (mother listed first). The blue box is the distribution of the PWD allele expression percentage in P2 brains of 18 F1mice from the AKR X PWD cross. The gene name is listed at the top of the figure. The color of the left and right strip label depicts the known X-inactivation status in mouse and human, respectively (orange, genes that escape X inactivation; purple, genes that partially escape X inactivation; blue, genes subject to X inactivation; black, not available). Note that every gene that undergoes X inactivation shows a consistent bias toward excess inactivation of the Xp (a sign test shows the bias to by highly significant; P < 1.5 × 10^-8).