Figure 9.13. Mutations can cause abnormal RNA splicing by activation of cryptic splice sites.

Figure 9.13Mutations can cause abnormal RNA splicing by activation of cryptic splice sites

This figure illustrates activation of a cryptic splice acceptor sequence located within an intron (compare Figure 9.12 which illustrates activation of a cryptic splice donor site within an exon). A mutation can result in the alteration of a sequence which is not important for RNA splicing so as to create a new, alternative splice site. In the example illustrated, the mutation is envisaged to change a single nucleotide in intron 1. The nucleotide happens to occur within a cryptic splice site sequence that is closely related to the splice acceptor consensus sequence but, unlike the splice acceptor sites in Figure 9.11, shows a difference with respect to the conserved AG dinucleotide (see Figure 1.15). The mutation overcomes this difference and so can activate the cryptic splice site so that it competes with the natural splice acceptor site. If it is used by the splicing apparatus, a novel exon, exon 2A, results, which contains additional sequence which may or may not result in a frameshift.

From: Chapter 9, Instability of the human genome: mutation and DNA repair

Cover of Human Molecular Genetics
Human Molecular Genetics. 2nd edition.
Strachan T, Read AP.
New York: Wiley-Liss; 1999.
Copyright © 1999, Garland Science.

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