Exon 8 was targeted with an sgRNA (targeting TCCTGACTTCTCCAGACTTG) and an ssODN template (CCGTCCCCTGTATTCCAACCCACCTCTCAATGGGGCCCGGATCGCAGCAACCATTCTGACGTCTCCGGATTTAGGTAAGCAATGGTAACGATTACTAGCTGTTCCGTGCTACAGCTCCATGAATGGAAAAG) using CRISPR/Cas9 technology with the aim to create a p.R337G mutation. The actual result was an unintended insertion/duplication of a single T (A on forward strand, after chr8:96596111 (GRCm39)), which results in a frameshift and premature stop codon.