E1i1 oligo activates cryptic site in exon 1

Here's a report of an unusual splice response to a Morpholino targeting the e1i1 junction. We'd expect the common outcome, insertion of intron 1. Instead, the splice was redirected to a cryptic splice site in exon 1, resulting in a shortened mature transcript. The new splice site knocked the downstream sequence out of frame, so this produced a good knockdown.

Belcher B, Vestal J, Lane S, Kell M, Smith L, Camarata T. The zebrafish paralog six2b is required for early proximal pronephros morphogenesis. Sci Rep. 2023 Nov 11;13(1):19699. doi: 10.1038/s41598-023-47046-3.
https://www.nature.com/articles/s41598-023-47046-3