Diagrams of the nine classes of alternative splicing. These are: Alternate Acceptor (AA), Alternate Donor (AD), Alternate Terminal Exon (ATE), Retained Exon and Skipped Exon (RE/SE), Initiation within an Intron (IWI), Termination within an Intron (TWI), and Spliced Intron and Retained Intron (RI/SI). The black boxed regions represent the coding region while the white boxed regions represent the 5' and 3' UTR regions. Introns are represented by a single line.
Campbell et al. BMC Genomics 2006 7:327 doi:10.1186/1471-2164-7-327