CRISPR/Cas9 technology was used to design guide RNAs that disrupt exons 59 and 62 of mouse Itpr1. Three founder mice with a deletion in exon 59 at a high mosaic rate died soon after birth for unknown reasons. Another mouse line with a seven-base pair deletion (c.8238_8244delAGCCGGC) in the last exon of Itpr1 which resulted in a frameshift and readthrough mutation was established and used for the study. (J:308935)