Tyrosine codon 174 (TAT) in exon 4 was changed to cysteine (TGT) (c.521A>G, p.Y174C) using an sgRNA (targeting TATAAATATGAAGGTGTGCGTGG) and an ssODN template with CRISPR/Cas9 technology. The mutation is the equivalent of the same human mutation associated with riboflavin-responsive exercise intolerance (RREI). (J:338257)