A TI{CRIMIC.TG4.1} DNA cassette has been inserted into Nna1, in a coding intron. This is predicted to truncate all annotated transcripts and to gene trap a subset of them (the 8 transcripts with intron phase 1). The insertion is also within Nadsyn, not in a coding intron, and is not predicted to gene trap this gene. The TI{CRIMIC.TG4.1} cassette was inserted via the CRISPR/Cas-9 drop-in technique, using a dsDNA donor vector with homology arms of length 200bp. The sgRNA sequence used to target the gene was: TAGAAAGAGCTTTCACTGCAGGG.