Computational identification of the AS was performed by using the resulting filtered set of H-InvDB transcripts as follows (Figure 1): 1. The genomic position of each exon-intron boundary was compared with those of the other transcripts belonging to the same locus. For the comparison, a �}2 bp allowance was made; 2. If a transcript had a part of the exonic sequence in the first/last exon inside conformed intronic regions of the other transcripts, they were regarded as being 5'/3'-end AS variants; 3. If a transcript had a part of an internal exonic sequence inside a confirmed intronic region of other transcripts, they were recognized as being Internal AS variants. Identified AS variants were also classified into five basic AS patterns (Figure 2) and other patterns regarding transcript initiation/termination if their AS exons were located in 5'/3'-end of variants (Figure 3).

Figure 1. Scheme of AS decision

Figure 2. Basic AS patterns

Figure 3. AS relating transcription initiation/termination