CRISPR/Cas9 technology generated a 5-bp deletion (TGCGC) plus a single base pair insertion (A) in exon 18 (c.1450_1455delTGTGC, c.1454_1455insA), resulting in a frameshift mutation 91 residues into the catalytic domain (aa483) and a subsequent early termination codon at amino acid 507 and a truncated protein devoid of the catalytic domain. RNAseq analysis from hippocampal tissue shows a 3-fold decrease in RNA levels compared to in wild-type mice. Homozygotes are devoid of catalytic activity.