Exons 1 and 4 were targeted with two sgRNAs (targeting GGAGCTCAATCGACGCCTGG and GCACAGGAGACCCTACTAAA) using CRISPR/Cas9 technology, resulting in an 8 bp deletion in exon 1 (CGCCTGGA chr3:87878561-87878568 (GRCm39)) that creates a reading frame shift and premature stop codon. (J:314040)