Using CRISPR/Cas9 genomic engineering in rats via homologous end-joining in fertilized embryos, we have knocked'in a humanized CHRNA6 3'UTR in place of the natural CHRNA6 3'UTR of the Sprague Dawley rat line. This new genetically modified CHRNA6C123G allele carries homozygous GG nucleotide modification at position 123 within the CHRNA6 gene 3'UTR.