Arginine codon 591 (CGT) was targeted for change to a tryptophan codon (TGG)(p.R591W) with sgRNAs (targeting GCTGTGTCAGCTCCTGACGGAGG and GGAAGCTGCCAGCCTCCGTCAGG) and an ssODN template (CAGCAGTTGGAGGCAGCACGTCGGGGCCAGCAGGAGAGCACGGAGGAAGCTGCCAGCCTCtGgCAGGAGCTGACACAGCAGCAGGAAATCTACGGGCAAGGTGTGGGGGCGTGGCGGTGTGTG) using CRISPR/CAS9 technology. This mutation mimics the human p.R587W variant associated with susceptibility to alopecia areata.