Figure 4

Intron retention ratio is correlated with cassette exon, mutually exclusive exon and intron retention splicing events. Frequency of matched alternative splicing event types in 1,000 random re-sampling exons representing the background distribution is compared with the observed number of each splicing event (highlighted in red dotted line) for the exons with increased intron retention (3′SS IR ≥0.01; CNE, constitutive exon; CE, cassette exon; MXE, mutually exclusive exon; IR, intron retention; A3SS, alternative 3′ splice site; A5SS, alternative 5′ splice site; Table 1). CE, MXE and IR types are significantly enriched, whereas CNE is significantly reduced compared with background (at false discovery rate P-value = 0.001). A3SS and A5SS are not found to be enriched.