CRISPR/Cas9 technology using the Cas9D10A and gRNAs 5'-CCAGGCACAGTACCTGCAGC-3' and 5'-GGCGGGAGGTGCGAGGGCTG-3', generated a deletion in exon 3 that causes a frameshift in translation and premature termination. RNA expression in whole brain of heterozygotes is reduced to about 70% of the level in wild-type while protein is reduced to about 50% of that in wild-type mice.