This allele from IMPC was generated at Medical Research Council Harwell by injecting CAS9 RNA and 4 guide sequences CCCCGAATGGACTACTCTGCGAT, CCGAATGGACTACTCTGCGATAC, GTAGAAAGTGTAGCCGGGCGTGG, CTTTAATCCCAACACTCGGGAGG, which resulted in a deletion of 571nucleotides flanking exon 3.