Figure 3. Low X:A expression ratios in human oocytes.

(a) Box plots of expression of genes with >0 FPKM in human MII oocytes. (b) The frequencies of expressed genes based on FPKM expression levels. The frequencies of X-linked and autosomal genes were significantly different for all categories (Fisher’s exact test, P-value < 0.01). (c) X:A median expression ratios (each chromosome) determined of each FPKM categories. Ave. means the average of each ratio according to the median expression levels. (d) X:A expression ratios (all autosomes) by bootstrap analysis in human MII oocytes. The red rhombus indicates the median. Error bars show 95% bootstrap confidence intervals. (e) Density plots of X-linked and autosomal genes with >0 FPKM. The P-value was calculated by the Kolmogorov-Smirnov test. (f) Frequencies based on log₂ expression levels. The frequency on X chromosomes was higher than that on autosomes for genes exhibiting low expression levels, while the opposite was true for genes exhibiting high expression levels.