A TI{CRIMIC.TG4.2} DNA cassette has been inserted into Usf, in a coding intron, and is predicted to gene trap all annotated transcripts of the gene. The insertion is also within lncRNA:CR32773, not in a coding intron, and is not predicted to gene trap this gene. The TI{CRIMIC.TG4.2} 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: TTAGGAATAAAGTTACCCAAAGG. 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.TG4.2} cassette is predicted to be accompanied by a deletion of 15bp of genomic sequence flanking the insertion site. The PCR product from the left flank was correct by sequencing and the PCR check of the right flank gave a band of the expected size.