A TI{CRIMIC.TG4.1} DNA cassette has been inserted into frj, in a coding intron. The insertion is less than 10bp from the splice donor junction, which might affect the effectiveness of the CRIMIC cassette to act as a gene trap and lead to the expression of GAL4. The TI{CRIMIC.TG4.1} cassette was inserted using the CRISPR/Cas9 technique together with a donor plasmid to drive homology directed repair. The sgRNA sequence used to target the gene was: ATAGGAAACTAGGTTGAATCTGG. The homology arms of the donor plasmid used were designed such that there is a small gap between the 3' end of the 5' arm and the 5' end of the 3' arm, thus the insertion of the TI{CRIMIC.TG4.1} cassette is predicted to be accompanied by a deletion of 20bp of genomic sequence flanking the insertion site.