Fig. 5

Circular RNAs have high abundance in many tissues and tissue-specific expression programs. a In many fetal tissues, especially regions of the brain, hundreds of genes have dominant circular isoforms in early and late time point samples. Late time point depicted for simplicity: for each organ, the total number of genes with greater circular RNA compared with linear RNA is plotted (p < 0.05). Asterisks indicate regions of the brain. b Many genes with tissue-specific increases in expression are also more highly expressed as circular compared with linear isoforms. Normalized expression levels from two samples, early (circles) and late time points (squares), in four genes illustrate this phenomenon (see “Materials and methods”). Statistically significant outliers (p < 0.001) include several subregions of the brain (DOPEY2 and the RNA binding protein R3HDM1), the frontal cortex (GLIS3) and skeletal muscle (RYR1); regression line (red) is plotted if there is a significant relationship with circular expression; x = y line plotted in black. JRPKM (junctional reads per kilobase per read mapped) have a comparable interpretation to RPKM (see “Materials and methods”)