Alternative splicing is a key element of eukaryotic gene expression. Almost all polymerase II transcripts are alternatively spliced. RNA is chemically and structurally more flexible than DNA, and can act as a catalyst. RNA is an active player in mediating genetic information, not just a static messenger. Almost the entire human genome is transcribed into RNA and new classes of noncoding RNA molecules are emerging. The number of diseases known to be associated with alternative splicing is steadily increasing.
