Alternative splicing

Production of different mature RNA sequences from the same precursor by changing which splice sites or exons are used. A cassette exon can be included in one transcript isoform and skipped in another.

Persistence of an intronic sequence in a transcript that would otherwise have been removed by RNA splicing. It can change coding potential, localization or transcript survival.

The inclusion fraction of an alternative exon or event. With effective included and skipped molecule abundances $I$ and $S$, $\psi =I/(I+S)$; expressing this fraction as a percentage gives $100\psi$. Raw junction counts can require opportunity or length correction before substitution.

A predictive set of rules connecting RNA sequence features and cellular regulators to alternative splicing outcomes. A useful code predicts the extent of exon inclusion in a specified cell type, rather than merely listing enriched motifs.