This allele was generated at The Centre for Phenogenomics by electroporating Cas9 ribonucleoprotein complexes with single guide RNAs having spacer sequences of GATGAGGGACGCACTGGCGT targeting the 5' side and TGGCCCGCAGGAGGTCTATG targeting the 3' side of a critical region (ENSMUSE00000203326) along with a single-strand oligonucleotide encoding a Bxb1 attB site. This resulted in a 357-bp deletion of Chr7 from 44,723,999 to 44,724,355 (GRCm39) with an insertion of a Bxb1 attB sequence (GGCTTGTCGACGACGGCGGTCTCCGTCGTCAGGATCATACACCTT).