The CtnsKO frameshift mutation is located within exon 4 of the Ctns coding sequence (counting from the ATG at bp position 252). The CRISPR/Cas9-induced frameshift mutation creates a 5bp  indel mutation (7 nucleotides deleted, 2 extra nucelotides inserted).
The translated sequence of the wildtype Ctns protein GLLDSDVEVALGTDSEDHLLLDPATFVYPAGSTRNQSVVITGLKAGNVKVVADSDDANKEI
is changed into
GLLDSDVEVALGTDSEDHLLLDPATFVYPAGSTPVGGDNWPQSRQRQSGRR*R* 
in the CtnsKO frameshift mutant generating a nonsense amino acid sequence after PAGST followed by 18 novel amino acids and two premature STOP (*) codons prior to the first transmembrane domain. See the associated files for the wild type and mutant sequences.